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The Select and Mask Tool in Photoshop CC is a powerful way to edit selective areas of your astrophotography images. Whether you want to separate the stars from your deep sky target, or apply subtle noise reduction to the background sky of your image, the select and mask feature will get you there.
Adobe Photoshop CC is an effective way to process astrophotography images, in a very creative and enjoyable way. If you use Photoshop to process your astrophotos like I do, this tutorial should be very useful to you.
About a year ago, I experienced the true power of the Select and Mask tool in Photoshop first hand. It has quickly become one of my favorite and most-used features of this application for processing my deep sky astrophotography images.
The Select and Mask tool allows you to get very specific about each and every edit you make to your images.
The Select and Mask Tool
The Select and Mask tool is Adobe Photoshop's powerful selection tool with advanced mask refinement options. It gives you complete control over your layer mask, and allows you to precisely define the edges of your selection.
When processing a deep sky astrophotography image, it is often beneficial to select different aspects of your images, and process them independently from one another. For example, there are times when you will want to increase the brightness of a nebula, without bloating the stars in your image.
When selecting these areas to process, you want to avoid creating a hard, unnatural edge between your selective area and the original. For this reason, being able to accurately feather your selection allows you to control the amount of softness between these areas and naturally blend them together.
In the example below, you'll see how I have increased the saturation of the Lagoon Nebula, without adding color noise to the background sky or stars.
Most Powerful Photoshop CC Tool for Astrophotography - YouTube
By using the Select and Mask tool to define the colors found in your deep sky target, you have complete control over the amount of saturation applied. By using the selection mask as a reference, you can confirm that you are only applying these effects to the nebula, and not the image as a whole.
Where to Find the Select and Mask Tool
Those that are using the latest version of Adobe Photoshop can navigate to the Select and Mask tool from the Main Menu Bar in a few ways. The most direct route to this feature is:
Select > Select and Mask
This is the path most people will take that are using the Select and Mask for general photography purposes, but not necessarily astrophotography. Here, you'll find tools such as the Quick Selection Tool and the Refine Edge Brush.
These features are useful for accurately masking a subject and removing them/including them on a new background. The Onion Skin view mode is particularly useful here, as it adjusts the opacity to provide you with a useful view of both layers at a time.
Although this is a "one-stop'shop" for refining your mask selection, I don't consider it to be the best way to utilize this tool for astrophotography image processing purposes. Instead, I prefer to start with the following path:
1. Select > Color Range
To start, use the traditional method of making your selection based on my original image processing workflow. This will give us a rough selection to start with, that we can refine further using the Select and Mask tool.
In the example below, I used the Sampled Colors option in the "Select" drop-down menu. When making a selective increase to color saturation, it's often best to sample the dominant colors of your deep sky object.
You can also use the Highlights selection mode, and adjust the Fuzziness slider to include the areas of light (signal) in your image. Keep in mind, this method will usually include your stars, as well as your deep sky target. In many cases, you will want to separate the selections between the two.
With the "Marching Ants" now showing (the dotted lines that Photoshop uses to indicate a selection), we can now refine our selection mask by navigating the Select and Mask button in the Select drop-down menu.
2. Select > Select and Mask
Here is where things get interesting. I suggest using the Black and White view mode, as it is the most helpful masking overlay for our purposes. The black areas of the image are un-selected, while the white areas are where we will isolate our adjustments to.
By far, the most powerful refinement tool here is the Feather slider. This is where we can adjust the amount of blending refinement between our subject and the rest of the image.
Feel free to adjust the Radius slider in the Edge Detection area if desired, although I usually leave this slider alone personally. You may find the Smooth slider found underneath the Global Refinements heading to be useful as well.
The great thing about the Select and Mask feature is the ability to preview changes made to your layer mask in real-time. You can adjust the sliders on the right, and monitor how these changes affect your selection before activating the selection.
I recommend only adjusting the Feather and Shift Edges sliders under the Global Refinements heading to start. In my opinion, these two adjustments have the biggest overall impact on the usefulness of your selection when it comes to astrophotography.
Shift Edges will expand your selection to include even more of your original selection (your subject). In turn, you are also selection more of the image overall, and becoming less selective about where you will apply edits to.
Feather will increase the softness of your selection at the edges, creating a smoother, more natural blend between the areas you enhance and the rest of your image. I believe that the true value of the Select and Mask tool lies in this feature alone.
As you can see, you've got some decisions to make here. I suggest using a middle ground between the examples above. Here are the exact settings I used to select the Omega Nebula in my example.
Applying Effects to Your Selection
The whole point of spending so much time and effort refining our selection is make powerful adjustments to the selection from increasing saturation to sharpness. Having the ability to make accurate selections that will blend seamlessly into the original image is an incredibly powerful tool.
Any adjustments made to the selection can then be isolated and organized in its own layer, and the level of opacity can be adjusted to taste. Slowly applying subtle enhancements to your image in a very intentional and responsible way can lead to some incredibly powerful images.
Some of the primary adjustments I apply to selected areas of my astrophotography images include:
All of these enhancements can be made to specific aspects of the image in an organized way. This technique ensures that you do not apply enhancements in one area, that degrade the image in another. For example, you can apply a stronger level of noise reduction to the areas of your background sky, while leaving the delicate sharpness of details within your deep sky object intact.
I hope that this tutorial has inspired you to try the valuable Select and Mask tool found within Adobe Photoshop CC. For my latest updates, tutorials, and reviews, please subscribe to the AstroBackyard Newsletter.
As usual, I only scratched the surface of what NEAF has to offer. I attend the Northeast Astronomy Forum (NEAF) as an amateur astrophotography enthusiast looking to get an up close look at the latest and greatest gear, but NEAF is a lot more than just vendor booths.
NEAF has been hosted by the Rockland Astronomy Club in Suffern, New York since 1991. This event has featured some incredible speakers over the years including Neil DeGrasse Tyson, Phil Plait, David Levy and many more.
NEAF is the largest and most exciting space, science, and astronomy show in the United States.
Have a look at the complete list of speakers that attended NEAF in 2019:
Jean Wright, NASA Space Shuttle Thermal Protection Specialist
Chris Go, Renowned Astro Imager
Kevin Schindler, Lowell Observatory
Bill Ayrey, The Apollo Space Suits & Beyond
Jim Green, NASA Chief Scientist
Don Pettit, NASA Astronaut
Alan Stern, NASA Principal Investigator
Dylan O’Donnell: Amateur Astronomer
James Hansen, Neil Armstrong biographer
Walt Cunningham, Apollo 7 Astronaut
In 2006, the Northeast Astro Imaging Conference (NEIAC) was added to the event, and has drawn in some of the biggest names in astrophotography from around the world.
NEAF: Northeast Astronomy Forum
The astronomy community is fortunate to have such a well organized and entertaining event to attend each year. I feel a little ashamed to spend so much time at the trade show portion of the event, without truly getting the full NEAF experience.
However, this year I managed to fit in one of the fascinating NEAF talks on day 2, and it was both educational and entertaining. The fact that this particular presentation was delivered by one of my favorite YouTubers may have had something to do with it.
Best. Weekend. Ever. (NEAF) - YouTube
Dylan O’Donnell is not only a down-to-Earth and likable guy, he’s also really smart. In fact, he is currently studying astronomy to advance his career, while balancing a family life and a popular YouTube channel. We were able to catch up and share ideas face to face, and it was one of my favorite parts of the trip.
NEAF is also a chance for me to connect with the amateur astrophotographers who have been inspired by AstroBackyard in some way. The conversations I have with these folks warm my heart and fill it with confidence, motivation, and joy.
Thank you to all of the members of the AstroBackyard Facebook page that shared the photos they took with me at the show!
What is NEAF?
The official NEAF website describes the event as "bringing you the universe in two exciting event-packed days". I can attest to this statement personally, as I have found it impossible to explore every angle of the event.
The solar observing field provides endless opportunities to explore our Sun while enjoying the spring weather, while inspiring talks captivate audiences inside the theater.
For many, the most exciting part about NEAF is the vendor displays from almost every brand and retailer (120 vendors and exhibitors). The products are not limited to hard goods such as telescope mounts and cameras.
Imaging software, remote observatories, astronomy publications, and even apparel are found within the walls of the gymnasium at Rockland Community College.
Many companies involved in the astronomy and astrophotography market use NEAF to unveil their latest creations. From well known brands with rich histories like Celestron and Meade, to up and comers like Pegasus Astro and Rainbow Astro; the trade show floor represent years of innovation in visual astronomy and astrophotography equipment.
It was impossible to visit every booth at the show and explore, because conversations with like-minded astrophotography enthusiasts tend to run long. Sharing photos, discussing backyard observatory plans, and helping to decide which telescope to purchase next were covered in detail during my time in Suffern, New York.
There are a number of telescope retailers that set up shop at NEAF. This includes High Point Scientific, Woodland Hills Camera and Telescopes, and Cloud Break Optics to name a few. The majority of the vendor booths at NEAF are from the brands themselves, from start-up companies to ones that have been around for over 50 years.
Local retailer High Point Scientific is a staple vendor of the event, and have been attending the event since from the beginning. They even purchase many the showroom floor demos at NEAF to sell at a discount on their website.
NEAF hosts 120 vendors and exhibitors at Rockland Community College.
I had a chance to catch up with the friendly team at High Point Scientific, to discuss the evolving energy at NEAF and the astronomy hobby as a whole. They recognize the new breed of "photographer-inspired" amateur astronomer, which is why they have been incredibly supportive of my website and YouTube channel.
Some of the products that were talked about most during my conversations were the new cameras from ZWO ASI, the impressively portable iOptron CEM40, the William Optics RedCat 51, and most recently, the Celestron 8-inch RASA. These items were likely brought to my attention from the crowd due to my previous experiences in the backyard, but I predict that they will also make a big impact this year.
I have developed a great relationship with Optolong filters, and it was great to finally meet my contact at Optolong who made the long journey from China to attend NEAF. Melisa Liu is dedicated to her brand and has made every effort to show her support to AstroBackyard and the amateur astrophotography community.
It was also great to catch up with the team at Pegasus Astro face-to-face, and get the inside track on their new Focus Cube and Dewmaster controller. They also have a new version of their extremely popular Ultimate Powerbox, and it is now smaller and more powerful.
Chatting with Evans and Angelos of Pegasus Astro.
I really love their dedication to support amateur astrophotographers, as all of their creations were born out of solutions to their personal imaging needs. Evans and Angelos have been very supportive of AstroBackyard and it was great to finally meet them in person.
Sky-Watcher continues to have a strong presence at NEAF with an impressive amount of telescopes on display. After a positive experience with the Sky-Watcher EQ6-R Pro and Esprit 100, and had some positive feedback to share and of course, a huge thank you. Kevin Legore has been very supportive of AstroBackyard from the beginning and I appreciate all of the advice he has provided over the years.
The team at the Meade booth was very helpful in answering the questions I had about their new Meade DSI IV mono imaging camera. Because I am early tester of this camera, there are a few things I can do to help them develop the software and user experience based on actual backyard use from an amateur astrophotographer.
It is impossible to anticipate every possible scenario this camera will face, so companies like Meade rely on user feedback to improve their products.
ZWO ASI was thrilled to see me in person, and were very thankful for the video content I have shared featuring their products. This was the case last year as well, which shows that they like to keep a pulse on the hobby and their users.
I praised them for the incredible user experience I had with the ASI294MC Pro, ASI290mm Mini, and of course, the ASIair. ZWO’s new ASI6200MC Pro was a hot topic at NEAF, along with their new 1.25” OAG helical focuser.
I witnessed Dylan O’Donnell filming at the Celestron booth, with an impressive looking film crew following him around. In fact, the backdrop for the Celestron booth at NEAF was one of Dylan’s many photos of the Carina nebula, that had to be at least 20-feet wide. It was wonderful to chat with Dylan about our experiences using the Celestron RASA 8 F/2, from both ends of the world.
He had to travel 30 hours for us to finally meet in person, so next time I'll make the long flight to collaborate. A trip to Australia to visit the southern skies of Byron Bay sounds like a great idea to me.
Dylan O'Donnell visiting the Celestron booth at NEAF.
Up-and-comers like Rainbow Astro give us a glimpse into the future. They offer a harmonic drive robotic telescope mount that does not require a counterweight. The company was founded by professionals in the field of robotics, and take a new approach to telescope tracking for astrophotography.
I found the design to be quite revolutionary, and I expect it to gain traction in the amateur astrophotography world as they continue to develop the technology.
The software companies continue to push the envelop of what's possible using amateur astronomy equipment. After an impressive demonstration of the PRISM software by Hyperion, I now realize that backyard photographers have access to the same powerful tools that are used at professional observatories at their fingertips.
I enjoyed an enlightening demonstration of the PRISM software from Hyperion Astronomy.
As you can tell, I spent the majority of my time engaging with amateur astrophotographers and the companies responsible for much of the gear we own. NEAF is much more than that, as it really an event that celebrates astronomy as a whole.
The inspiring NEAF talks are the most unique and powerful aspect of this event, and I plan to enjoy more of them the next time I attend the wonderful gathering at Rockland Community college next April.
The Celestron RASA 8 F/2 Astrograph is a modern astrophotography telescope with an optical design that allows you to collect deep sky images using short exposure times. Based on the popular 11" version, the 8” model is the most affordable RASA (Rowe-Ackermann Schmidt Astrograph) in Celestron’s lineup.
The RASA optical system presents a modern and practical approach to extremely fast deep sky astrophotography.
I should start off by saying that until now, I’ve never used an SCT (Schmidt-Cassegrain Telescope) in my life. I’ve always been a refractor guy. So my experiences with the RASA 8 F/2 will not only be a first in terms of this telescope design, but also the unique Rowe-Ackermann Schmidt Astrograph optical system.
The Celestron RASA 8 F/2 is not a visual telescope, it was designed exclusively for deep sky astrophotography. The size of the RASA 8 does not allow you to use it with a DSLR camera, as the camera body will obstruct too much of the corrector plate on the front of the telescope.
The 8" Celestron Rowe-Ackermann Schmidt Astrograph.
That’s right, the RASA 8 F/2 requires that you mount the camera to the telescope’s objective end. A dedicated astronomy camera with a chip no bigger than APS-C is needed to enjoy the RASA 8.
The 8” model was designed to be used with modern CCD and CMOS dedicated astronomy cameras like the ZWO ASI294MC Pro, or ASI1600MM Pro. Full frame sensor cameras that are less than 4” in diameter will work, but performance will be poor at the edges of the field.
In this post, I’ll share my experiences using a telescope that is more than twice as fast (f-ratio of F/2) as any other telescope I’ve used for astrophotography. This 8-Inch Celestron Rowe-Ackermann F/2 Schmidt Astrograph was generously loaned to me from High Point Scientific for review.
Celestron RASA 8 F/2 Review
The Celestron RASA 8 F/2 Has ARRIVED (Astrophotography) - YouTube
In this review, I’ll take the RASA out for a test drive in my backyard for some deep sky imaging. I’ll explain how to fasten a camera to this telescope to utilize the unique RASA optical system that is based on the idea of Celestron’s original Schmidt camera.
I will be mounting the Celestron RASA 8 F/2 to a Celestron CGX-L computerized equatorial telescope mount, and connecting a one-shot-color astronomy camera, the ZWO ASI294MC Pro. The goal is to capture an impressive color deep sky image using short exposures (60-seconds) without the use of autoguiding.
I have the Starizona filter drawer for ZWO cameras to house my 2" light pollution and narrowband filters. This not only allows me to easily swap filters on the RASA, but also provides the right amount of spacing between the camera sensor and the objective of the telescope.
The RASA Backstory
The backstory of Celestron’s RASA telescope is very interesting, and begins in the 1970’s with the introduction of Celestron’s Schmidt cameras for use with 35mm photographic film. Later on, the Faster camera was introduced that was created by removing the secondary mirror from a standard C8 SCT, and replacing it with a series of lenses on the corrector plate.
Originally, the SBIG PixCel 255 camera was the CCD camera used with the Fastar system. By 1999, this was replaced by the SBIG ST-237, with a whopping 640 x 480 array that covered 40 x 30 arcminutes of sky. By today’s standards this is not very wide, but back then it was considered to be a rather wide-field image.
Celestron eventually discontinued Faster, and the idea was taken over by Starizona in the form of HyperStar. This product could now expose an impressive 27mm image circle, which was enough for the APS-C sized sensors found in a DSLR camera. Starizona provides conversion kits and camera adapters for many Celestron SCT telescopes from the C6 to the C14.
The Hyperstar system allowed amateur astrophotography enthusiasts to capture deep sky images in a short period of time thanks to the lightning fast F/2 optics. Hyperstar paved the way for the RASA design as this add-on component introduced fast, short-exposure, wide-field imaging to the amateur astronomy world.
Thanks to David Rowe and Mark Ackermann, the amateur astrophotography community can enjoy the unique capabilities of the original Celestron Schmidt camera design in a practical astrograph.
The optical design of the RASA OTA.
Why this is a Big Deal
As you may know, I have used apochromatic refractor telescopes over the past 8 years for deep sky astrophotography. I love that they are compact, lightweight, and capable of capturing incredibly sharp, flat, and well corrected images.
One of the few downsides of this optical design is the f-ratio (focal ratio), which is considered “slow” when compared to systems such as an F/3.9 Newtonian or F/2 RASA. The telescope’s focal ratio determines its ability to collect light in a given amount of time.
This means that a “faster” f-ratio” of F/2 can gather light (signal) on a deep sky object much faster than a refractor telescope with a focal ratio of F/6. Mathematically, this speed is not linear, meaning that F/2 is not just 2X as fast F/4 - it’s MUCH faster than that! (I am not sure of the exact calculation).
The point is, the 8” RASA I have is the fastest telescope I’ve ever used for astrophotography, by a landslide. Nothing else even comes close.
In practical terms, I can expect to collect the same amount of signal in a 60-second exposure with the RASA 8 as I would in a 3 to 4-minute exposure using an F/7 refractor. I can do this without sacrificing a wide, flat field of view. The 400mm focal length of the RASA 8 F/2 provides a wide, optical aberration free image.
At this focal length and proposed exposure times, tasks such as autoguiding become less important. A 60-second image is not nearly long enough to reveal subtle inaccuracies in the telescope mounts tracking abilities, especially when using a mount such as the Celestron CGX-L equipped with a QHY Polemaster.
Image Circle: 22mm (.86") Ø, 3.15° Useable field: 32mm (1.26") Ø, 4.6°, only minimal performance loss at edge of FOV Back focus with included camera adapter: 25mm (.98") Back focus from top of threaded collar: 29mm (1.14") Optical Tube: Aluminum Optical Tube Length: 628mm (24.7") length | 235mm (9.3") diameter Focuser: Ultra-Stable Focusing System Optical Tube Weight: 17 lbs (7.7 kg) Other Features: Air-cooling system, integrated filter mount Included items: M42 camera adapter, C-thread camera adapter, fan battery pack Dovetail: CGE Dovetail Bar
My Backyard Imaging Experience
On my first night out with the RASA 8, I photographed two (relatively small) deep sky targets. The focal length of the RASA (400mm) is better suited for expansive nebulae such as the Lagoon Nebula and North America Nebula, but those targets do not rise high enough in the sky for imaging for another month or two.
My selected targets for testing the RASA were Thor’s Helmet, an emission nebula in the constellation Canis Major, and the Pinwheel Galaxy, a face-on spiral galaxy in Ursa Major. The moon was about 75% illuminated during my imaging session.
To filter out moonlight and city light pollution, I used two astrophotography filters to capture my targets:
Mounting my astrophotography camera to the front of the telescope was a bizarre experience. Those of you that have experienced the HyperStar system with an SCT in the past will find this to be a familiar experience, but it was brand new to me.
The Celestron M42 adapter and compression ring made it very easy to mount my ASI294MC Pro camera and Starizona filter drawer. This configuration provides the recommended 29mm of back focus spacing between the camera sensor the connection to the corrector plate on the RASA.
Starizona designed this filter drawer to cater to RASA owners looking for a solution to changing filters. You simply need to remove the compression ring from the corrector, release the adapter, and pull the filter drawer out to swap your 2” filter out.
This came in very handy as I went from photographing a narrowband emission nebula to a broadband galaxy on the same night. The RASA OTA package also includes a C-Thread camera adapter, and adapters for other camera types (including Sony mirrorless cameras) are available.
The Starizona Filter Slider for select ZWO cameras.
The Telescope Mount
I have mounted the 8-inch RASA to a Celestron CGX-L computerized telescope mount using the CGE dovetail rail on the telescope. This heavy-duty EQ mount has a payload capacity of 75 pounds, so it is completely overpowered (or over-mounted) for the lightweight (17 pound) 8-inch RASA tube. Over-mounting is never a bad thing, and the RASA looked absolutely great in an “All-Celestron” black and orange setup.
It’s easy to single out one particular piece of your gear to hold responsible for a successful imaging session, whether it’s the telescope, mount, or camera. In reality, it is the combination of everything working together in harmony, from the filter used to target selection.
The Celestron 8-inch RASA F/2 mounted to a Celestron CGX-L EQ mount.
The Celestron CGX-L has been an absolute pleasure to use since I first flipped the switch on. This should come as no surprise as this is a modern “flagship” telescope mount from one of the oldest telescope companies in the world.
From the moment I slewed to my first target using the 8-inch RASA on the CGX-L, I knew I was working with an imaging system that was going to be a lot of fun. Thor's helmet appeared prominently in the center of the image frame in a 6-second live loop exposure.
The Imaging Sequence Plan
To showcase the extremely fast F/2 optics of the RASA, I restricted the exposure time of my individual light frames to 60-seconds. The nebula and galaxy targets I have chosen were well-exposed at this exposure length, and I processed data sets of 60-seconds images to create an impressive final image.
The 1-minute long exposures showed a lot of promise as I reviewed the auto-stretched debayed previews appearing on the ASIair mobile app.
Without providing the exact math behind the equation (which I am unable to calculate), I am capturing more than 3X as much signal (light) in each shot using the F/2 RASA over my F/7 apochromatic refractor.
The images were loaded into DeepSkyStacker for integration and calibration (I only used dark frames), to give me an image with a healthy sign-to-noise ratio for final processing in Photoshop.
I did not use any sort of autoguiding system for improved tracking accuracy on the Celestron CGX-L. However, I did capitalize on the precise alignment provided by the QHY PoleMaster before I started taking images.
The process involved using a specialized ADM adapter that fastened to the CGE dovetail rail of the RASA 8. The PoleMaster sat directly underneath the OTA, which positions it precisely in line with the RA axis of the telescope mount. I ran through the PoleMaster alignment routine on my PC for an accurate polar alignment before beginning my imaging session.
The QHY PoleMaster fastened to the CGE dovetail rail of the RASA.
At this focal length and these exposure times, autoguiding is not necessary. The telescope and camera were well balanced in both axis of the mount, and the spot-on polar alignment took care of the rest.
I still can’t get over the fact that I can get away with a 1-star alignment now that the PoleMaster has been installed.
If you're looking to autoguide with the RASA 8 F/2, it's important to note that the optical tube does not include a guide scope. However, it can be fitted with a bracket for this configuration thanks to the threaded mounting holes at the rear cell of the astrograph.
Running the Camera with an ASIair
What can I say, the ZWO ASIair makes it so much more enjoyable to run an imaging session. The wireless connection to the camera and straightforward controls of the mobile app let me do other things while the camera runs (like go in the house).
The software is stable and I can confidently record my images onto the micro USB card on the ASIair and transfer them over to my PC the next morning. I have found that the ASIair mobile app cools the camera to -30C much faster than Astro Photography Tool.
The debayered image previews the ASIair displays after each image is captured are a helpful reference of camera settings, tracking accuracy and image framing. I still prefer to use APT for my initial camera setup including focus and framing, but that’s because it’s already there to complete my polar alignment routine.
However, once those tasks are complete I can put my PC away and just keep my tablet on me to monitor the ASIair. From a cable management perspective, the ASIair is much more organized as the USB cable running from the camera connects to unit less than 2” away, and rides along with the telescope and mount.
Cooling Fan and Dew Shield
The 8” RASA includes a connection for a cooling fan and power adapter at the base of the telescope. The cooling fan helps to reach thermal equilibrium with the outside air by pulling air through the mesh vents located near the rear of the telescope.
The greater the temperature difference is between the OTA and the outside air, the longer it will take to cool down.
It is recommended to use a dew shield with the RASA as the corrector plates are quite susceptible to dew accumulation. I don’t have a dew shield for this telescope yet, but it would be a wise addition for those nights where the temperature drops significantly.
Focusing the RASA
The focuser is unlike anything I’ve ever used before, and I really love it. Celestron calls it the "Ultra-Stable Focus System", which minimized unwanted lateral movement of the primary mirror when focusing or slewing the telescope.
To focus the RASA, you just need to turn the little knob at the rear of the tube, that moves the entire primary mirror forward and backward. As you can imagine, focusing at F2 is tricky.
The focuser knob is smooth and responsive, without the need to lock anything down once you have found a tight focus on your stars. A single turn of the focus knob does not move the primary mirror much. This gives you a lot of precision when achieving the sharpest focus possible.
Celestron offers an optional focus motor specifically designed for this telescope, which is a probably a smart upgrade if you are getting serious about focus. I found the stock focuser to work great so far.
The images below are the results of my limited exposure times using the RASA 8 and ASI294MC Pro from the city. To give you an idea of the amount of light pollution I shoot in, my skies are considered to be a Class 6 on the Bortle Scale (orange zone).
I am thrilled with my results. It felt like I was processing images that were captured using 5-minute exposures using a DSLR camera on my refractors.
The Pinwheel Galaxy - 72 x 60-seconds.
Thor's Helmet - 138 x 60-seconds.
The Celestron RASA 8 is suitable for those that want an ultra-fast astrograph with a wide, flat field of view. 400mm at a blazing fast F/2 is an amazing combination of speed and focal length.
If your into wide, flat field images of large deep sky objects, these are useful specs. If you’re going after small galaxies, a traditional SCT or Ritchey-Chrétien Telescope are better choices, but your exposure times will need to be a lot longer, and autoguiding is a must.
I've used a ton of refractors and camera lenses at this focal length, but nothing that comes close to F/2. For comparison, one of my favorite APO refractors, the Sky-Watcher Esprit 100 is 550mm and F/5.5.
At F/2, 60-second exposures reveal as much detail as I'd expect to see in a 3-minute exposure or longer. A telescope’s focal ratio is the most important factor to consider when gauging its light gathering ability.
Between the one-shot-color camera, and the amount of detail recorded in a 60-second exposure, you can really maximize your output in a limited amount of time.
I’d love to see what the RASA can do when the Milky Way returns next month.
The simplicity of having one camera running, controlled by the wireless ASIair is a lot of fun. Being able to produce an impressive deep sky image using 1-minute exposures is something I could get used to, especially on those nights when I only get a clear hour or two.
If you image with a DSLR, or want to make visual observations, the RASA 8 F/2 isn’t for you. The size of the camera and sensor have to be a good match for the RASA to keep the central obstruction to under 93mm, and capture a well illuminated field.
A filter drawer/adapter that provides the correct spacing between your camera and the optical window cell is an essential accessory in my opinion, so make sure you’ve got that aspect covered.
Now, if you’ll excuse me I’m going to collect more time on the Pinwheel Galaxy. Until next time, clear skies.
The QHY PoleMaster electronic polar scope was designed to make your polar alignment routine easier, and more precise. No matter which camera tracker or telescope mount you’re using, when it comes to astrophotography, accurate polar alignment is critical.
If you have ever struggled to polar align your telescope mount with the north or south celestial pole, the QHY PoleMaster may just be your new best friend. With a slew of recent technical headaches and an unforgiving winter, my appreciation for devices that make my life easier has grown.
The QHY PoleMaster delivered exceptional results for me on my first night out with it. The dedicated polar alignment software was easy to use, and the camera produced a crystal clear image of the star field surrounding the north celestial pole.
I experienced that cliche moment I expect all backyard astrophotographers had with this device their first night where I thought, “I should have been using one of these a long time ago”. It’s true.
The PoleMaster I am using is for my Sky-Watcher EQ6-R Pro EQ mount, and I have fastened it to the mount using the dedicated QHY adapter for this model.
In this post, I’ll review the QHY PoleMaster from the perspective of an experienced amateur backyard astrophotographer who’s spent a lot of time manual polar aligning mounts.
When others would mention the QHY PoleMaster to me, I would say that I just don’t need one. I felt comfortable manually polar aligning my telescope mounts and camera trackers, from the iOptron SkyGuider Pro, to the Sky-Watcher EQ6-R Pro.
My deep sky astrophotography setup with a PoleMaster fastened to the polar axis of the telescope mount.
I use a mobile app (Polar Finder) that gives me a readout of the current position of the north celestial pole, and fine tune the altitude and azimuth controls of my mount to line the axis up as best as possible.
So why do I need a QHY PoleMaster to aid me in this process? Because sometimes “as best as possible” just isn’t good enough. Oh, and kneeling on the cold pavement or wet grass to get behind that polar scope kinda sucks too.
What about confirming the position of Polaris in the illuminated reticle after I’ve started imaging? Depending on the angle my telescope is pointed (on the EQ6-R), this simply isn’t an option. In fact, there is a long list of benefits to using the QHY PoleMaster over a manual alignment routine that I seemed to have ignored up until now.
Polar Alignment speed, accuracy and experience improvements with the QHY PoleMaster:
I can polar align faster, at dusk
My old method of polar alignment was fast, this one is faster. I no longer need to wait until I can see Polaris with my naked eye to get started.
I don’t have to get on the ground
I like to leave my telescope mount tripod legs at their minimum height for maximum stability. However, this makes getting underneath the polar scope tricky and somewhat painful (I feel old).
Improved polar alignment accuracy
A high precision camera can achieve a higher level of polar alignment accuracy than “my best try”. The imaging camera in the PoleMaster has a resolution of 30 arc seconds.
I can monitor and confirm my polar alignment at any time
Any slight amount of drift due to bumping the mount, sinking into the lawn or other factors I had no way of monitoring are now easy to identify and fix.
No more 3-star alignment routines
Why didn’t someone tell me about this feature? The spot-on accuracy of the PoleMaster means that only a 1-star alignment routine is needed for your telescope mount to learn the sky.
The pointing accuracy of your telescope mount will vary depending on the focal length of the telescope you are using for astrophotography.
Eliminating any cone error in your telescope mount will improve your pointing accuracy even further. The Sky-Watcher EQ6-R Pro has an option to adjust this.
QHY PoleMaster EQ Mount Polar Alignment Camera Specifications:
Field of View: 11 degrees by 8 degrees
Interface: Mini USB 2.0
Resolution: Approximately 30 Arc seconds
Weight: 115 g (0.25 lb)
What’s included in the box
This PoleMaster was sent to me from High Point Scientific for review. The team at High Point made sure to include the necessary adapter for my EQ telescope mount. Here is a look at everything that comes with the PoleMaster:
PoleMaster camera body
Lens cap with a lanyard
Mini USB 2.0 cable
Mount adaptor cap
M4 hardware for attaching the adaptor
Allen key for lens focus adjustment
When ordering your PoleMaster, make sure to specify which mount adapter you need for your specific telescope mount.
The PoleMaster I am using is for my Sky-Watcher EQ6-R Pro EQ mount, and I have fastened it to the mount using the dedicated QHY adapter for this model. The hardware was easy to install, and the materials used and overall finish of this device is attractive.
The adapter for my Sky-Watcher EQ6-R came with a tiny Allen key to adjust tension, so I could securely lock the PoleMaster into the front of the polar axis scope of the mount.
The QHY PoleMaster adapter for the Sky-Watcher EQ6-R
There are two parts to the mount adapter for the PoleMaster, the camera base disc that attaches to the camera body, and the camera mount ring that you need to secure to the mount. You secure the camera base disc to the mounting ring using a thumb screw.
For the EQ6-R mount adapter I used, there were three tiny grub screws to tighten using the supplied Allen key to lock the adapter into place.
Installing the QHY PoleMaster and adapter on my Sky-Watcher EQ6-R Pro Mount.
The device connects to my PC via a Mini USB 2.0 cable, with miniature locking screws to avoid yanking the cable out by accident. I wish more of my device connectors had this. The manual instructs you to position the USB port of the PoleMaster to the left hand side when looking at the device head on.
I ran the mini USB 2.0 cable from the PoleMaster into my recently upgraded powered USB hub, which consolidates the various astrophotography devices I have running to a single USB cable into my laptop.
The adapter allows you to take the PoleMaster off of the mount while not in use or in storage, but I think I'll leave it right where it is. The tiny camera adds no weight to my rig and maintains a low profile.
I'll just have to make sure I don't bang anything against the device by accident when setting up. The included lens cap should stay on the PoleMaster when not in use to protect the lens.
Software and Downloads
All of the software and drivers needed to run the PoleMaster device were found on the QHY website. The company has recently updated their site, which lead me on a bit of a wild goose chase.
Rather then using the URL printed on the green card that came with the camera, I simply “Googled “QHY PoleMaster Driver” to find the appropriate section of the QHY website.
Here, I downloaded the latest stable driver for the PoleMaster, along with the dedicated software needed to communicate with the camera and control parameters such as gain and exposure length.
With the 2 downloads unpacked and installed, I ran the PoleMaster software on my field laptop with the camera connected. The QHY PoleMaster manual (link below) was to-the-point and helpful through this process, and instructed me to click the “connect” button.
I heard the reassuring “new device connected” chime on my Windows 10 OS after plugging in the PoleMaster, so I new the camera was successfully recognized by my PC.
If your PC has trouble recognizing astrophotography accessories and devices, I recommend unplugging the device and reconnecting to a new USB port. Monitor the Windows device manager to troubleshoot any connection issues.
After hitting the “connect” button, the PoleMaster delivered a live-view loop of the stars in the northern sky. The mount was already roughly polar aligned to my latitude at 43 degrees north, and pointed in the general direction of Polaris in my backyard.
The PoleMaster camera lens has an 11 x 6 degree of field of view. This means that the pole star should be visible if the mount has been roughly polar aligned.
Even though it was not completely dark out yet, I could see a formation of stars in the display screen right off the bat. After zooming out to 75% view, the north star, Polaris was obvious.
Us northern hemisphere folk have the luxury of having a bright pole star. In the southern hemisphere, the PoleMaster Uses Sigma Octans as a reference, which is a bit trickier to identify.
Using the PoleMaster Software
The PoleMaster software user interface.
The first thing you'll want to do is adjust the gain and exposure settings so that it is easy to identify the pole star and a number of adjacent stars in the field.
The software walks you through a simple process of identifying and confirming the pole star. The process involves matching an overlay of star positions with your current view of Polaris and surrounding stars.
The rotate tool on the left hand sidebar lets you rotate the star pattern overlay using your mouse or trackpad to line up with your current live view of the north star.
Then, you are asked to rotate the RA axis of your telescope mount to determine the rotation of the mechanical axis. By rotating your mounts right ascension axis by 15 degrees or more, the software can confirm this value.
Fine tuning my the polar alignment accuracy of my telescope mount using the QHY PoleMaster.
I made the mistake of releasing the RA clutch of the mount to perform this step, when the manual clearly states that this must done using the hand controller or mount control software such as EQMOD.
The reason for this specification is that by releasing the RA clutch, you shift the rotational center of the mount. Instead, keep the RA clutch locked, and perform this rotation by pressing the east button on the keypad.
Next the on-screen prompts tell you to confirm the center of rotation. Eventually, you will get to a point where the application displays a small green circle. This is exactly where the pole star needs to be. At this point, the ultra-fine adjustments you make to your polar alignment are far beyond what’s possible with the naked eye.
I wonder how far off the north celestial pole I was in the past?
Aligning the polar axis of my telescope mount with the true north celestial pole using the PoleMaster.
There is a reason so many amateur astrophotography enthusiasts own a QHY PoleMaster. Whether you want to improve your polar alignment accuracy, save time, or ditch those 2nd and 3rd alignment stars when setting up - the PoleMaster can make your time under the stars more efficient.
The pressure and urgency to capture images increases when you have a limited window of clear sky time. When even a single aspect of your astrophotography setup is off, you can quickly squander your night sky bounty for the night.
Devices like the QHY PoleMaster help to optimize your imaging experience and allow you to focus on the photography side of things, like collecting images. The peace of mind knowing that your telescope mount is optimized for the apparent rotation of the night sky is one aspect of the hobby every one of us can appreciate.
At under $300 USD for the QHY PoleMaster Electronic Polar Scope is an obvious upgrade to any amateur setup, whether you think you need one or not. Is it possible to get your rig accurately polar aligned without the PoleMaster? Sure.
But in a hobby where little things make the difference between a good image, and a great one - I like to take every advantage I can get.
I’ve just returned from a vacation to Costa Rica with the goal of capturing some astrophotography images from the resort. Being so close to the equator, the night sky featured many new southern hemisphere deep sky targets I had never seen before.
Aside from astrophotography (including an impromptu Facebook Live stream from our balcony) my wife and I also enjoyed a private birding tour and some much needed relaxation. The average temperature from home in Canada was around -10 degrees Celsius, in Costa Rica, 33.
Despite the pleasant temperatures and impressive number of clear nights during our trip, it took some creativity and persistence to accomplish my astrophotography goals from this location. All-inclusive resorts never sleep, which means that the lights never go out.
In this post, I’ll share my experiences photographing the night sky from Guanacaste, Costa Rica. For a fun overview of my experience, and some of the raw emotions this trip included, please watch the video.
Astrophotography from COSTA RICA (Honeymoon) - YouTube
Astrophotography from Costa Rica (On our honeymoon).
Astrophotography in Costa Rica
The resort we stayed at was Dreams Las Mareas, located in the northwestern peninsula of Guanacaste. The closest city is La Cruz, which is very close to the Nicaraguan border.
While other focused on the all-you-can eat buffet, piña colada's and catamaran tours, I couldn’t help staring up at an entirely different looking night sky.
Attempting to take deep sky images through a telescope from a vacation resort in a foreign country has its challenges. As you will soon find out, those uncontrollable variables began to add up.
The location of our resort in Costa Rica.
A Preview of the Southern Sky
The first and most obvious looking change was just how high the Orion constellation was. How fortunate for those that live at this latitude to photograph the Orion Nebula near the zenith!
Below Sirius, in Orion, I saw the bright star Canopus for the first time. This star belongs to the southern constellation, Carina, which is non existent in mid Northern latitude skies.
In fact, there are numerous southern hemisphere constellations and deep sky objects observable from Costa Rica. I thought a trip to Australia would be necessary to see many of these targets.
My view of the night sky from 10 degrees north of the of the equator. (Stellarium)
Since I was still in the northern hemisphere, I could theoretically polar align my telescope mount using the North Star, Polaris. The north celestial pole doesn't land precisely on this star, but it's a fantastic reference point. The process of polar alignment is much more difficult in the southern hemisphere.
I have polar aligned my telescope mount countless times using the north star from home in Canada, but this time, Polaris sat just above the northern horizon. It was far too low to observe from the resort as it was blocked by the surrounding mountainous landscape and the hotel itself.
To polar align my portable iOptron SkyGuider pro, I guestimated the exact altitude of the polar axis, and it was nearly level with the horizon. At only 10 degrees north, there was no way I’d be able to spot it.
I ran a series of test exposures at 30-seconds in length to improve my rough polar alignment. Luckily the focal length (250mm) of the telescope I brought is more forgiving in terms of tracking accuracy than higher magnification instruments. The RedCat 51 is also extremely lightweight and portable, which makes it a superb choice for wide field deep sky imaging while traveling.
My DSLR astrophotography setup including a telescope and tracking mount.
Portable Astrophotography Gear for an Airplane
I packed all of the astrophotography equipment needed for wide field deep sky imaging in my carry-on bag on to the airplane. This included the telescope, camera, mount, tripod, filter, and adapters.
This “deep sky travel kit” included a capable equatorial telescope mount, the iOptron SkyGuider pro. The EQ head of the mount was easily packed into my bag, along with the wedge and collapsible carbon fiber tripod. This camera mount matches the apparent rotation of the night sky using a right ascension tracking motor.
The telescope is a William Optics RedCat 51 refractor. The RedCat weighs just 3.2 lbs, and can easily be mounted to a lightweight astro tracker for long exposure imaging.
Inside of the RedCat, sits a 2-inch Optolong L-Pro filter that I’ve pre-threaded into the M48 adapter of the telescope. This proved to be a great way to record images in broadband true color while reducing the immediate light pollution from the resort.
The camera is a stock Canon EOS 7D Mark II. When I say "stock", I mean that this DSLR has not been modified for astrophotography by removing the internal IR cut filter. The camera threads on the RedCat 51 via a dedicated Canon EOS t-ring adapter.
My Portable Deep Sky Astrophotography Rig (Carry-on friendly)
The astrophotography gear used for my shot of the Carina Nebula.
The Game Plan
Due to factors such as lack of a precise polar alignment, and setting up in a high traffic area, I decided to shoot 30-second exposures at ISO 6400. This way, I could at least complete a number of successful images rather than having to discard many of them in the pre-processing stage.
The constant wave of wind gusts made keeping my camera and telescope ultra-steady during an exposure very difficult. The limited exposure lengths helped to reduce this effect.
The location of our resort meant that there was very little light pollution in the direction of the nearby Atlantic Ocean. However, this resort chooses to shoot high intensity spotlights toward the night sky during their nightly shows.
There was an unfortunate amount of localized light pollution from the many lighting fixtures that stay on all night long. The mild light pollution filter inside of the telescope adapter helped to reduce this unnatural glow.
I generally like to see all of the lights go out at night, but the lighted pathways on the resort came in handy when navigating to my deep sky imaging location near the front lobby. As an experiment, I took a photo looking towards the constellation Orion from the pathway near our room. As you can see, there is a lot of light coming from all angles.
Deep Sky Imaging Location
I decided to stay on the resort to run the camera and telescope. The beach was a better spot in terms of darkness, but it was just too risky to leave the security of the resort at night in a foreign country.
The wind was also much stronger and unpredictable by the water, and I had enough to worry about already. I did, however, sneak down to the beach one night to take some wide angle tripod shots of the night sky. Unfortunately, the timing of this idea was off, as my photos were spoiled due to rare clouds at night.
The Location of my Deep Sky Astrophotography Session from Costa Rica.
Shooting from the balcony of our room would have been ideal, but the window of sky was limited to the west. I did attempt to photograph a deep sky object from the balcony through the telescope, but it was more of an experiment than anything else.
There was a large open area of grass outside of the main lobby of the resort, and the security staff by the front entrance gave me some peace of mind. This is where I planted the tripod and iOptron SkyGuider pro with my telescope attached. I kept the tripod very low to the ground for added stability during strong winds.
The Target: Carina Nebula
Coming from a northern hemisphere sky with the usual constellations and deep sky objects, how could I not attempt the Carina Nebula from Costa Rica? This is a “bucket list” target for me, and one I didn’t imagine capturing without a trip to Australia.
The Carina Nebula (also known as the Eta Carinae Nebula) is a magnitude 1 deep sky object, so 30-second exposures were enough to reveal much of this complex and large nebula. This emission nebula is cataloged as NGC 3372, and includes multiple objects within it.
See this annotated image for a closer look at the many deep sky objects found inside of the Great Nebula in Carina.
The Carina Nebula
Distance to Earth: 7,500 light years
Radius: 230 light years
Designations: NGC 3372, ESO 128-EN013, GC 2197, h 3295, Caldwell 92
Cataloged deep sky objects inside of the Carina Nebula:
Trumpler 14 Star Cluster
Trumpler 16 Star Cluster
The Carina Nebula does not reach a high altitude in the sky from northern Costa Rica, which meant I needed a low view to the horizon to capture it. The Carina Nebula just barely cleared the treeline from our resort at 10pm.
As it turned out, one of the biggest obstacles I had to overcome was wind. The wind gusts were as strong as 40km an hour at times, completely ruining the current exposure being captured on my portable rig.
This element was particularly painful to experience, as it can occur when absolutely every other measure of success has been taken.
To compensate for wind, I used my body to block the telescope from the direction the wind was blowing from. Also, I was limited to 30-second exposures, as this offered the best chance of completing a frame without interruption.
My final image of the Carina Nebula includes just over 9-minutes of total exposure time. The following image consists of 18 x 30-second images at ISO 6400.
The Carina Nebula | 18 x 30-Seconds @ ISO 6400
Once I registered and stacked the sub frames in DeepSkyStacker, I had a total overall integration time of 9 minutes, and 30 seconds. Processing the stacked integration in Photoshop was an exciting experience, and I took my time. The individual 30-second light frames were very noisy, which was to be expected when shooting on a hot night using an ISO of 6400.
The stacking process helped improve the signal to noise ratio a great deal. However, the noise reduction actions in post processing seem to have softened the image up significantly. In these situations, it’s a fine balance between noise and overall sharpness.
I really enjoyed processing this image, and loaded it into nova.astronomy.net to be annotated. As you can see, my photo includes NGC 3293, NGC 3324 in the frame as well. This website is a great way to annotate your own astrophotography images online).
I would have loved to capture more data on the Carina Nebula, and attempted to capture images of more southern targets like the Centaurus A galaxy. However, I left my new bride in the hotel room during these ventures, and she was very patient and understanding to give me the time I had.
I witnessed the Southern Cross, Carina, Canopus, and much further into the southern night sky than ever before. I could hear the white-faced monkeys in the forest as my camera collected each exposure on the Carina Nebula. I stood alone in a field of grass in the dark while the rest of the guests slept or tied one on at the bar.
Deep sky astrophotography from Costa Rica in early March presents the best of two hemispheres, from Orion to the Carina Nebula. If you are planning on travelling to Costa Rica in the future, I highly suggest that you don’t forget to pack your telescope.
Despite the excitement of a moving into a new house under Bortle Class 6 skies, I've had a rough start to the new year in terms of astrophotography.
The weather has not been friendly, from -30 C nights to consecutive weeks of precipitation and clouds. However, this has given me some time to get my astrophotography gear organized in the garage for my next imaging session. My weather app shows that Saturday has a chance of clear skies for about 2 hours, and I'll be ready.
In this post, I'll provide an update as to the astrophotography gear I'll be using next. My goal is that you find some inspiration in this setup, and to keep you guys up to date with the latest happenings in the AstroBackyard.
As you progress in your journey of deep sky astrophotography, I think you'll find that you gravitate towards equipment that delivers a painless and enjoyable experience. To me, this hobby is about more than just aperture and guiding accuracy. Yes, improving the quality of my images is very important, but its the road to get there that I think I enjoy most.
If you have been paying attention to the AstroBackyard YouTube Channel, it may appear as if I am collecting all of the latest and greatest gear to bring to show-and-tell. The truth is, if I don't actually get a chance to use and share my experiences with these items, it's of little value to the amateur astrophotography community.
We're half way through the month of February, and I've got a staggering amount of exciting telescopes, mounts and accessories on loan for review. I'll share more information about these products over the coming months, as I continue to educate myself about them and their intended purpose.
This post will focus on a deep sky astrophotography rig that I have set up in a semi-permanent fashion. This means that I can quickly set up this rig for some deep sky imaging if the weather provides an opening through the clouds. I do not own a permanent observatory, so everything needs to be carried from my garage to a spot in the yard.
This rig has been commissioned into action for this month based on the current temperatures and weather conditions I've been experiencing. Options such as a larger mount or telescope are reserved for more accommodating temperatures and predictable conditions.
Astrophotography Gear UPDATE | Ready to Rock! - YouTube
Here is each piece of the deep sky astrophotography setup I have put together:
Telescope Mount: Sky-Watcher EQ6-R Pro
Primary Imaging Telescope: Explore Scientific ED 102 CF
Filters: Optolong LRGB Filter Set (2"), Optolong L Pro
Motorized Focuser: Pegasus Astro Stepper Motor Kit and DFMC
Accessories: Pegasus Astro Pocket Power Box, Kendrik Dew Heater Bands
As you can see, there are some familiar faces on this setup. There are also some exciting new additions such as the Meade Deep Sky Imager IV and Xagyl Filter Wheel. I have never captured images using a filter wheel before, so this should be an eye-opening experience.
Another noticeable change from my last deep sky setup is the use of a monochrome astronomy camera in place of the OSC (One-Shot-Color) ZWO ASI294MC Pro. The Meade DSI IV uses the same camera sensor found in the incredibly popular ZWO ASI1600MM, the camera behind countless jaw-dropping images from Chuck Ayoub, Dylan O'Donnell, and Diego Colonello.
Let's take a look at each piece of the rig in detail.
The Sky-Watcher EQ6-R has been an absolute pleasure to use since it arrived in the fall of 2018 from Sky-Watcher. This computerized equatorial telescope mount is reliable and capable. The EQ6 model has been refined over the years, a big improvement over my old HEQ5 Pro SynScan in terms of build quality, technology and features.
It is a step up from the HEQ5 in terms of payload capacity as well, offering a commendable 44-pound payload. This is more than enough for most of the telescopes I use for astrophotography, including the Explore Scientific ED 102 CF refractor that's currently riding on top.
Sky-Watcher EQ6-R Pro Computerized Equatorial Telescope Mount.
I have yet to control the EQ6-R via my computer, tasks such as star-alignment and object slewing have all been accomplished using the hand controller thus far. While browsing the Cloudy Nights forum, I discovered an incredibly helpful article by John Upton about controlling SynScan telescope mounts from your computer.
The Sky-Watcher EQ6-R I have has the new Version 5 SynScan hand controller with the USB A-Male to B Male (Printer Cable) on the bottom. This does not require the use of the PC Direct Mode when controlling the mount using Astro Photography Tool (APT).
Long story short, I plan to leverage the power of ASCOM and PC control to further automate this setup over the coming months.
Primary Imaging Telescope
Ah, the Explore Scientific ED 102 CF. My reliable 102 is beginning to rival the number of imaging hours I put on the 80mm version of this triplet years ago.
The ED 102 has a practical focal length and ratio for most of the deep sky targets I am interested in capturing (714mm and F/7). The 102mm diameter gives it enough aperture to give it some extra light gathering power for faint nebulae and galaxies over a smaller refractor, yet it is still very lightweight and easy to manage.
Explore Scientific ED 102 CF Triplet Apochromatic Refractor.
I have taken countless images through the ED 102, but collecting light on deep sky targets in monochrome with a filter wheel is all new territory.
The reason I have chosen to enlist the old ED 102 instead of the Esprit 100 or William Optics Z73 is the modifications I have made to it. I have fitted a motorized focuser and focus motor controller box to this refractor to help me fine tune my focus on the fly.
I have photographed many incredible deep sky objects with this telescope over the past 3 years and highly recommend it to anyone looking for a high performance imaging APO for astrophotography.
Primary Imaging Camera
The Meade DSI IV is a rather new dedicated astronomy camera in the amateur astrophotography world, and there is not a lot of information about it yet. Ontario Telescope and Accessories saw an opportunity for me to share information about this camera and dive into monochrome LRGB imaging.
When I learned that the Meade DSI IV mono houses the same sensor as the ASI 1600MM, I immediately agreed to this arrangement. The Meade DSI IV mono marks as a return to the dedicated astronomy camera market by Meade, and I have high hopes for this 4/3" format 16 Megapixel CMOS sensor.
Meade Deep Sky Imager IV Mono CMOS Camera.
The thermo-electric cooler will ensure that my images are virtually noise free when compared to the images I capture on a DSLR. This camera requires an external AC power adapter to run the cooling system, and connects to my PC using a USB 3.0 cable.
I have installed all of the necessary software to run this camera using APT on my imaging laptop, and have tested everything out to make sure the images are recorded properly. I will not be using the included SkyCapture camera control software that was bundled with the camera.
I have always used a field flattener and reducer with the ES ED102 Triplet to maintain a flat imaging field of stars in my images. The Starfield 0.8X reducer/flattener is a perfect match for this telescope as it was designed for imaging refractors of F/5.5 and above.
This flattener requires 55mm of back focus, which I have achieved between the camera sensor on the Meade DSI IV and back of the flattener. The required distance was accomplished by using a t-mount adapter ring to thread the camera to the Xagyl filter wheel.
Threaded to the reducer/flattener, is an Optolong L-Pro light pollution filter. This 2-inch filter sits in front of the LRGB filter set residing inside of the electronic filter wheel (EFW). So, each colored filter in the EFW (and the luminance filter), will benefit from a a subtle reduction in the amount of artificial light pollution collected when imaging in the backyard.
This is a bit of an experiment, so I plan on imaging without this filter in the future to compare results.
The autoguiding telescope is a Starfield 50mm guide scope. This miniature refractor telescope has a focal length of 190mm, and serves as a lightweight solution for autoguiding. I have used this guide scope on a few rigs now, and I enjoy the precision of the helical micro-focuser.
I've mounted the guide scope to the cradle ring handle of the ED 102, as there is a convenient slot to mount accessories using 1/4" screws. This is better position than the default finder scope bracket that I have used in the past. The autoguiding combo now sits directly center over the primary imaging scope.
This mounting position also allows me to use a finder scope with the ED 102 and autoguiding combo attached, which is nice to have for my 3-star alignment procedure. Both the guide scope and finder scope add very little extra weight to this setup.
Starfield 50mm Guide Scope Package with Altair GPCAM2.
The camera I am using on this setup is my well used Altair Astro GPCAM2 Mono. This camera is sensitive enough to provide accurate autoguiding results using the PHD2 Guiding software, and has proven to be a dependable little camera over the past 2 years.
Its low profile takes up very little space on the telescope and is virtually weightless. This autoguiding combo is a painless way to add some seriously powerful tracking abilities of your existing telescope mount without adding a heavy telescope or unneeded complexity to your setup.
The camera connects to to my USB hub with a USB A Male to B Male cable to display the live loop images on my PC, while the ST-4 cable communicates subtle commands to the EQ6-R for improved tacking accuracy via PHD.
The Altair GPCAM2 Mono Guide Camera.
This a new experience for me, and I am still getting used to seeing a big black plate in front of the camera. This is a Xagyl 5-position filter wheel with 48mm slots certainly requires some space, but this Xagyl model is only 0.7" thick.
I've moved the imaging payload around with everything attached and balanced, and it appears as though I won't have to worry about the filter wheel crashing into anything. I will certainly keep an eye on things, though.
With the included adapter from Xagyl, the filter wheel added an additional 19mm of back focus which I needed to account for when fastening the camera and flattener.
The filter wheel connects to my USB hub with a mini-USB cable, and thankfully does not require another power source and additional cord to my setup.
Xagyl 5-Position x 2" Electronic Filter Wheel.
The team at Optolong has provided me with a complete set of Optolong LRGB filters to use in conjunction with this monochrome camera. This is my first foray into the world of LRGB imaging with a monochrome camera, as I have never owned a filter wheel to automate the process.
These filters are the 2-inch (48mm) round mounted versions that I have carefully threaded into the Xagyl 5-position filter wheel. I have tested the selection of each filter using APT and everything appears to be working flawlessly thus far.
The images I take through the Optolong filters will showcase not only the potential of the Meade DSI IV mono, but the LRGB filter set as well. Unfortunately, I have nothing to compare them too, but I will produce a full-color deep sky image with this system so you can make an informed decision for yourself.
Motorized Focuser and Controller
I installed a Pegasus Astro Motorized Focuser on my telescope in late 2017. Since then I have enjoyed the added functionality of my ED 102, which comes in really handy when monitoring my gear outside remotely. I used to have to run outside to make a small tweak to my focus, which would often result in a lengthy back and forth process.
Now, I can make fine adjustments to the focus on the fly using a combination of Team Viewer for remote access of my imaging laptop, and the focus control panel in APT. As the temperature changes throughout the night, I often need to tweak my original focus position from the start of my imaging session.
Pegasus Astro Stepper Motor Kit and Dual Focus Motor Controller.
I simply observe any changes to the star sharpness and quality over the last few images, and make any slight adjustments as needed in between frames using the Pegasus Dual Motor Focus Controller (DMFC). APT provides useful HFD and FWHM metrics to measure the focus quality of your stars.
I have not experienced the autofocus feature in APT yet, but plan to investigate this further this year.
My favorite astrophotography accessory of this setup has to be the Pegasus Astro Pocket Power Box. If you remember my video from last year, this little blue box allows me to better organize and balance my deep sky imaging rig by connecting almost everything on top of the telescope.
It powers my primary imaging camera, DFMC, and 2 dew heater straps. This not only cuts down on the number of cables running from my power bar and computer to the telescope, but also allows me to control the output of each port remotely using dedicated software from my PC.
The Pegasus Astro Pocket Power Box.
I've also mounted an Anker USB 3.0 7-Port hub to the eyepiece tray spreader underneath the EQ6-R mount head. This gives me all of the USB ports I need for my astrophotography cameras and accessories.
What I have plugged into the Anker 7-Port USB Hub:
Meade DSI IV Mono Imaging Camera
Altair GPCAM2 Guide Camera
Pegasus Astro Pocket Power Box
Xagyl 5-Position Filter Wheel
With all of the cables carefully run down from the telescope into the 7-Port hub underneath, I only need to connect a single USB 3.0 cable to my imaging laptop. I ordered a nice 9-foot A-Male to B Male USB 3.0 cable for this connection to give me some flexibility when setting up.
The computer I use for deep sky imaging is a portable laptop I purchased on Amazon last summer. This computer has all of the necessary software for astrophotography image acquisition installed such as APT, PHD2 Guiding, and the Pegasus Astro software for the Pocket Power Box (PPB), and DMFC.
To combat moisture on the objective lens of my primary imaging telescope and guide scope, I use Kendrick dew heater bands that are powered by the PPB.
The Bottom Line
Cable management was a top priority of mine, as the goal is to be able to control this mount remotely from inside the house when it gets too cold to be out all night. I've used over 25 Velcro ties to bundle up the cables as neatly as possible to avoid potential cables snags. Some soft tubing to completely conceal this cables might look best, but I'll monitor how things operate like this first.
The entire imaging payload is balanced perfectly on top of the Sky-Watcher EQ6-R in both axis. I've pointed the telescope in almost every possible position, and nothing catches or strikes the tripod. I still do not feel comfortable slewing to a new target remotely (nor do I have the PC connection set up yet), so for now that operation will only take place when I am sitting next to the rig.
The most important aspect of this rig are the automation and portability qualities. What I mean by that is, I can quickly carry this rig out of the garage to set up and image on a night with a limited amount of clear sky time. Without the counterweights attached, I am able to lift the entire load up and place it in the yard without having to re-assemble it.
If the telescope were larger and heavier, I wouldn't be able to do this safely without sacrificing my back or the chance of dropping something.
Once I set up the tripod and polar align the mount, I can perform a quick 2-star alignment and slew to my target. Once I am locked on and framed properly, I'll head inside the house to monitor the imaging session using Team Viewer to access my laptop outside.
From here, I can make slight adjustments to focus and take images through each LRGB filter. I expect I'll need a window of at least 3 clear hours to produce a color deep image using this system.
Now, if I could just decide on a target...
You may have noticed the absence of some existing new astrophotography gear I have talked about over the past couple of months. Namely the ZWO ASIair WiFi camera control unit and the Celestron CGX-L telescope mount.
Both of these products will be used in the near future as the weather improves and I can dedicate longer periods of time under the night sky. The plan is to use the ASIair on the Celestron CGX-L, with the new 8" RASA SCT attached.
I've got a few other new products to share as well, so I hope you stick around to see them over the coming months. Until next time, clear skies.
William Optics is a company known for creating high performance apochromatic refractors, and constantly updating and refining their designs. The RedCat 51 Petzval APO is the latest creation from the company that can't sit still, and it is bound to shake up the industry once more.
I am fortunate enough to have been granted early access to this exciting Petzval apochromat that debuts in early March 2019.
What makes the William Optics Redcat 51 so special? The 4-element Petzval design, unique focal length and helical focuser. The sleek red finish of the RedCat 51 signals its individuality and charm. It is unlike any other astrophotography telescope on the market, and one that I have been waiting to get my hands on since reviewing the early concept designs last year.
While shooting the unboxing video for the RedCat, I came to the conclusion that this is hands down the most beautiful looking telescope I have ever seen in terms of style and design. This is a signature quality of the William Optics brand and they continue to push the envelope with new and dramatic concepts.
William Optics RedCat 51 (Unboxing) - YouTube
The William Optics RedCat 51
The design goals for the RedCat included creating an affordable refractor that uses the highest quality glass, and delivers a flat imaging field with unmatched color correction. In this post, I’ll break down the specifications of the RedCat and explain why I think this little quadruplet will be one of the most sought after products in 2019.
Have you ever seen a more dramatic video for an astronomy product in your life?
The RedCat bridges the gap between an astrophotography telescope and a telephoto lens.
The 250mm focal length and F/4.9 focal ratio mean that the RedCat can be enjoyed as much by wildlife photographers as it is by amateur astrophotographers. The helical focuser makes focusing a fast-moving targets such as birds much easier than ever before.
For those of you that don’t know, I am also an avid bird photographer. Once I discovered the clarity and sharpness provided by a apochromatic refractor telescope, I began using my astrophotography telescopes for bird photography. These telescopes were too heavy to use handheld, and were challenging to focus on moving subjects.
Roughly 8 years later, William Optics releases a high-end apochromatic refractor that targets the wildlife photography market. The RedCat encapsulates two of my greatest passions (astrophotography and bird photography) in a single product.
The RedCat 51 is small, beautifully designed, and versatile. The early astrophotography image examples shared by William Optics are breathtaking. Aside from looking good, and some promising looking results in terms of performance, the RedCat 51 has some handy features to improve the user experience.
Before I cover items such as the filter slot and modular mounting options, let’s dive into the core specifications of the RedCat 51.
RedCat 51 Specifications:
Optical Design: Petzval Apochromatic Refractor (4 elements in 3 groups)
Lens Type: Prime
Focal Length: 250mm
Weight: 3.2 lbs
Focuser: Calibrated Helical
Mounting Style: Vixen/Arca-Swiss
The RedCat 51 mounted to an iOptron SkyGuider Pro.
Focal Length: 250mm
First off, the RedCat 51 has a focal length of 250mm. What does this mean for astrophotography? It means extremely wide-field deep sky images. If you consider a 480mm refractor to be a wide-field ‘scope, the RedCat is nearly twice as wide!
Massive deep sky objects such as the Carina Nebula will fit into the image frame in their entirety. Large nebulae that traditionally fill the frame in a typical wide field setup and captured with plenty of surrounding space and additional star clusters and nebulae in the frame.
Until the RedCat came along, 250mm was a focal length reserved for those that employ a prime camera lens for astrophotography. Now amateur astrophotographers have the option of using a flat-field APO that easily mounts to their existing equatorial mount for deep sky imaging at this magnification range.
For wildlife photography, this focal length is also quite useful, especially when you consider the all-important f-ratio of this lens. 250mm is enough reach for many larger birds such as hawks and owls, but will require a steady hand and gimbal head for the best chance of a sharp shot.
The FPL-53 Objective lens of the RedCat 51 Petzval APO.
Focal Ratio: F/4.9
When it comes to photography (of filming) birds, it’s all about light. Fast shutter speeds are required to capture a bird in motion, and this demands a fast lens to adequately expose the shot. F/4.9 isn't incredibly fast in the world of camera lenses, but when you consider that this is essentially a refractor telescope - it's about as much light gathering power as you'll find on the market.
For comparison, the RedCat is almost a stop faster than the extremely popular Canon EF 400mm F/5.6L lens. William Optics has released some incredible wildlife footage shot using the RedCat, a testament to this quality. Low light situations such as a cloudy day made wildlife photography tough with my old F/6 William Optics Z72. The speedy RedCat is a completely different animal.
51mm Lens Diameter
As the name eludes to, the RedCat has a 51mm objective lens. In the world of astrophotography telescopes, this is absolutely tiny! If you thought the adorable little Zenithstar 61 was cute, wait until you see the RedCat. But this kitten has claws (I couldn’t resist).
The 51mm objective lens on the RedCat is made from top quality FPL-53 and FPL-51 glass (synthetic fluorite) which creates a flat frame image from corner to corner, even when utilizing the entire image circle with a full frame camera.
The small size of the RedCat means keeping overall weight to a minimum, despite the extra glass. The RedCat 51 weighs only 3.2 pounds even through the design requires 4 elements in 3 groups. For owners looking for a high-end telescope to mount on the iOptron SkyGuider Pro, the RedCat is an ideal candidate.
Lens Structure: Petzval
A Petzval lens design involves a low-dispersion doublet in combination with two elements farther down the optical path to both speed up the f-ratio of the telescope, and flatten the image field. There is no need to use a field flattener with the RedCat, adding to its simplicity and practicality in the field.
The Petzval quadruplet lens design is well corrected, and incredibly sharp. You can expect pinpoint stars to edges of your image. If you don’t believe me, have a look at this image of the Witch Head Nebula taken using the RedCat 51 by Mehmet Ergün.
These traits will surely make the RedCat a popular choice for high resolution deep sky astrophotography imaging. Portability and design aside, the RedCat is an affordable option for those looking to own a top-of-the-line astrophotography telescope. A comparable refractor on a much larger scale is the Takahashi FSQ106.
Example images taken using the William Optics RedCat 51 on Flickr.
Yes, a helical focuser! This design aspect is completely changes the user experience of the RedCat, whether you use it to photograph the night sky, or a black-crowned night heron. I have used a number of apochromatic refractors for daytime photography in the past, but none of them felt natural because of the of rack and pinion focuser.
Aside from the impressive lens design, the helical focuser is the single biggest differentiating factor between the RedCat and a typical imaging APO. The focuser draw tube is calibrated and features printed mm spacing marks for precise adjustments. The black textured focuser ring is made out of soft rubber for a comfortable grip.
Adjusting focus during frantic wildlife photography moments is now much more fluid and responsive, while the precision and rigidity needed for deep sky astrophotography is retained. The focuser tension ring allows you to precisely control the level of friction desired, and also can also lock the tube in place when needed.
The field rotator resembles the face of a luxury brand watch, which is exactly the inspiration William Optics used when designing the rotator markings on the RedCat. Every degree of the field rotator is marked to help aid in the process of creating a mosaic. There is a small white arrow on the M48 adapter to use as a reference point when setting your camera orientation.
This level of attention to detail is noteworthy, as this subtle feature indicates input from actual amateur astrophotographer needs.
You’ll find that many of the hidden “extras” on the RedCat 51 follow this mindset as well, including the small white teflon rings inside of the mounting ring. This small, yet thoughtful detail allows the user to smoothly rotate your imaging train.
The field rotator includes markings for each each degree of rotation.
The M48 thread adapter allows you to fasten your DSLR or dedicated astronomy camera to the RedCat for astrophotography or daytime photography. The imaging circle completely covers a full frame camera sensor for edge to edge illumination with a flat-field.
Speaking of covering your camera sensor, the M48 adapter includes an internal thread for 48mm (2-inch) threaded filters. This is a convenient location to place your favorite light pollution or narrowband astrophotography filter.
Owners of Canon, Nikon, Sony or Pentax cameras will be happy to know that their camera bodies are a perfect fit for the RedCat with the necessary t-mount and adapter hardware. The M48 end adapter must be removed to apply the matching red William Optics erecting diagonal.
Mounting Base and Lens Collar
The base of the RedCat 51 was specially designed to avoid adding extra weight to the telescope, yet provides a reliable platform for the the demanding positions of astronomical imaging. The matching red low profile dovetail bar can be used with either a standard Vixen mount saddle, or the photography based Arca-Swiss style mounting bracket.
The dovetail plate includes standard ¼ inch threads, and simply needs to be flipped over to accommodate your desired mounting configuration. Deciding on the configuration of this aspect of the telescope will depend on your primary use of the RedCat.
The optical tube itself can also rotate easily thanks to the lens collar and release knob. This is similar to the design you’ll find on high end telephoto camera lenses, but with 2 extras.There are modular mounting options on the lens collar. Here, you can fasten accessories such as a shotgun microphone or red dot finder scope.
Integrated Bahtinov Focusing Mask
To top things off, William Optics has included their signature diffraction spikes Bahtinov mask in the lens cap. This feature is handy for DSLR astrophotography imaging sessions when you need to quickly and accurately confirm the focus of your target. You simply need to aim the telescope towards a bright star to create the diffraction spike pattern.
The elongated star patterns displayed when pointed at a bright star create an obvious and distinct guideline to reference when using adjusting the helical focuser. The clear acrylic design of these masks make them much easier to use than the traditional opaque black Bahtinov masks.
The Bottom Line
The price tag of the William Optics RedCat 51 may seem a bit steep at first, but considering the pedigree of this refractor, it's right on the mark. Creating an affordable option for those looking for a premium imaging APO in small package was the overall goal of the RedCat design. I believe the RedCat is poised to have a big year, and look forward to the official unveiling at NEAF.
If you have interests in both wildlife photography and deep sky astrophotography as I do, you might feel like the RedCat was designed specifically for you. William Optics is brand that continues to innovative and create original products. In in world full of copycats, this little APO stands in a category of it's own.
This telescope will be available in early March 2019. You can keep up to date with this release of this telescope by visiting the official product page from William Optics.
The Celestron CGX-L is a robust, professional grade computerized equatorial mount with an impressive 75-lb payload capacity. The deep sky astrophotography potential of the Celestron CGX-L is obvious, and I intend to experience this benefit first-hand.
The CGX-L is the largest equatorial telescope mount I have ever used for astrophotography, with payload capacity that surpasses the incredible iOptron CEM60 (by 15 pounds). The added stability will come in handy when using the largest telescopes in my inventory, such as the William Optics FLT 132 refractor.
Later this year, I will run a complete Celestron rig that includes the exciting new Celestron 8” RASA F/2 SCT. This incredibly powerful GoTo telescope mount was generously loaned to me from High Point Scientific for review.
The Celestron CGX-L GoTo Equatorial Telescope Mount.
If you are new to astrophotography and computerized telescope mounts, a GoTo equatorial mount like the CGX-L allows you to choose an object from the hand controller database, and the mount will slew to your desired target. This includes Solar system objects such as planets and the moon, named stars, and deep sky objects.
The NexStar hand control screen on this mount will also display useful information about the selected object such as magnitude, constellation and extended information about the most popular objects. Needless to say, whether you’re using a telescope for visual use or for astrophotography, a GoTo telescope mount will spoil you.
In this post, I’ll go over the specifications and features of Celestron’s latest flagship telescope mount. I’ll also take you along for the ride as I prepare this mount for some backyard deep sky astrophotography from the city.
An Overview of the Celestron CGX-L Telescope Mount
The Celestron CGX-L computerized mount is capable of carrying Celestron’s largest optical tubes, and was designed for serious imagers and their backyard observatories. Despite the fact that this is the most massive telescope mount I’ve ever experienced, it actually has an exceptional load capacity to weight ratio.
Celestron designed the CGX-L to be as compact and portable as possible. Coming from someone who doesn’t own a backyard observatory, I can appreciate this feature! I’d love to fasten the CGX-L mount to a fixed concrete pier under a roll-off roof, but for now I’ll be carrying this mount in and outside of the garage, tripod and all.
In the past, I have enjoyed using equatorial telescope mounts from iOptron, Sky-Watcher, and yes, Celestron. My very first telescope mount for astrophotography was a Celestron Advanced Series CG-5, and it is responsible for many of the images in my photo gallery. The positive experiences I had with this entry-level Celestron telescope mount early on are why I fully expect to fall head over heels for the CGX-L.
The EQ mount head of the Celestron CGX-L is manageable considering its payload capacity.
I can't imagine traveling with the Celestron CGX-L mount, but that will depend on how manageable the setup process experience is in my backyard. For now, the idea is to build a semi-permanent deep sky imaging rig that utilizes all of the Celestron CGX-L's inspired features from my backyard.
Let’s have a look at the key design goals of the Celestron CGX-L.
Celestron CGX-L Design
The Celestron CGX-L hit the market in early 2017, and it brought several new, modern features to the world of observatory-class equatorial mounts. One of Celestron's key design goals for the CGX-L were to increase the diameter of the worm wheels to 144mm, which provides smoother movement and can drive heavier telescopes more efficiently.
The dovetail saddle on the CGX-L is an impressive 270mm in length, which owners of larger optical tubes will appreciate. It's reassuring to know that your expensive telescope and astrophotography accessories are safely secured to the mount head and with added security and stability of a larger saddle.
Because this mount is an attractive option for those looking to build a permanent, remote observatory, Celestron has included a number of remote operation-friendly features. This includes everything from built-in home and limit optical sensors to well-thought-out and convenient cable management options.
Attention was given to the ergonomic details of this mount, to make it as compact and manageable as possible for its size. Having moved this telescope mount from one house to another, I can honestly say that it was no more difficult to disassemble and transport than my much smaller Sky-Watcher EQ6-R Pro. The mount feels incredibly sturdy and heavy, and yet takes up a modest footprint despite its massive payload capacity.
The execution of a telescope mount that is both compact and easy to manage yet is observatory-grade is a testament to the evolution of our hobby. Decades of engineering and user-feedback have been applied to the CGX-L, and you can feel it when you use this mount.
The total kit weight including the tripod is 120 lbs.
Load capacity increased to 75 lbs
Additional auxiliary accessory ports
Autoguider port on the Dec axis
Larger 144 mm diameter worm wheels
Longer 270 mm dovetail saddle
70 mm stainless steel tripod legs with wide stance
Accessory tray for 1.25" x 2" eyepieces, and upright stand for smartphone or tablet
Optional add-on polar axis finderscope
WiFi support for StarSense AutoAlign and SkyPortal WiFi module
The head on the Celestron CGX-L has a relatively low profile. This makes it feel compact and stable, which you can feel when you place the mount on the tripod base. The mount uses Celestron's latest motors, that have been described from the manufacturer as having more torque, and improved slewing and tracking accuracy under heavy loads.
The heavy-duty belt-drive system in the CGX-L can be observed and monitored first-hand thanks to the ingenious clear windows covering these parts. This allows you to watch the underlying motor operation of the mount as it operates with your telescope gear on top.
These critical equatorial mount actions are normally hidden underneath a hard cover, and Celestron's transparency of this operation says a lot about their confidence in the design.
When it comes to the critically smooth operation needed for long exposure astrophotography, friction must be avoided at all costs. The guts of the CGX-L include a spring-loaded brass worm wheel and a stainless steel worm gear to optimize gear-mesh and deliver reliably smooth movements.
The size of the tripod next to an un-impressed Rudy (for scale).
Cable Management and Remote Operation
To me, there is nothing scarier than a cable snag that damages my photography equipment or the mount. I also have a somewhat unjustified fear of my camera or telescope striking a tripod leg during operation. It has never happened to me yet (knock on wood), but I have had a number of close calls over the years.
For this reason, I prefer to stay close by to my equipment when slewing to a new object. I can proactively help move any potentially hazardous cabling out of the way as the telescope changes position. But what about those that are running a telescope remotely, and can't be there in person to avoid disaster?
Mounts like the Celestron CGX-L are prepared for this scenario thanks to an internal cabling design. Both the power input jack and lower accessory ports remain in a stationary position while the mount slews to a new target. The mount also includes internal hard stops in both axes to prevent cable tension or a costly tripod strike.
This type of worry-free operation is absolutely critical for those that are using this telescope mount in a remote observatory. For non-permanent backyard imagers like myself, I can leverage these features to take my astrophotography imaging automation one step further. That means fewer trips outside to monitor the equipment, as I can comfortably slew to a new object or perform a meridian flip from inside the house.
The Celestron CGX-L includes clever "home sensors" that tell the mount exactly where the primary index position is. This feature allows you to start the mount in the home position even if it was in another orientation before a power reset. This is something I've never experienced before on any of my telescope mounts, and I can certainly see the benefits of this attribute when using the CGX-L in an observatory.
The built-in limit sensors will automatically stop the mount from slewing or tracking before reaching the hard stop fail-safe. The operational "safety" features of the CGX-L are imperative for observatory installations, yet could be a lifesaver to anyone using the mount in a portable backyard configuration like myself as well.
The RA and DEC clutch levers on the CGX-L are substantial and feel very secure.
An Improved Design
The EQ head position of the CGX-L is adjustable, which may help you optimize the center of gravity over the tripod once your astrophotography gear is mounted. This will also offer more flexibility in terms of latitude adjustments, as this mount is capable of setting latitudes of 3°- 65°.
The dual dovetail saddle provides convenient mounting options for both Vixen and Losmandy dovetail bar configurations. My Sky-Watcher Esprit 100 ED and William Optics Fluorostar 132 telescopes both feature the wider 3-inch “Losmandy” style dovetail for improved stability, and fit securely on the CGX-L.
The tripod itself is exceptionally solid and stable. The 70mm legs are the biggest I have ever seen, yet do not take up an absurd amount of space when collapsed. Celestron has noted that the legs now sit wider than ever before, which adds stability.
When I realized this subtle change, I instantly thought about how JMI will need to produce a new, wider Wheelie bar to accommodate the CGX-L. Speaking of subtle changes, the minimum height of the tripod has been lowered based on user feedback (not from me... I’m 6’3”!).
The integrated handle is very much appreciated when lugging the massive EQ head of the mount around when not attached to the tripod. It is extremely heavy, yes, but surprisingly manageable considering the incredible 75-lb payload capacity it can carry.
Telescope Control Software and Polar Alignment
The Celestron CGX-L includes their new PWI telescope control software that was co-developed by PlaneWave Instruments. Thanks to a feature known as "multi-point mount modeling", this mount boasts extremely precise pointing accuracy.
This should be interesting to test in the backyard with only an accurate polar alignment procedure beforehand (no plate-solving). I am no stranger to a 3-star alignment routine, and I look forward to seeing just how close the CGX-L comes to hitting that first alignment star.
Speaking of Polar Alignment, the Celestron CGX-L includes the well renowned All-Star Polar Alignment software in the hand controller. I haven't used this feature since my early days of deep sky astrophotography with my humble CG-5.
This software assisted polar alignment routine is an attractive option for those that don't want to use external tools or resources to align the polar axis of the mount. You can polar align the mount using any bright (named) star in the sky without using additional polar alignment accessories or apps.
The Celestron NexStar Hand Controller.
NexStar Controller and Electronics
Celestron's famous NexStar hand controller is included with the CGX-L, and includes and a practical USB 2.0 port. This where I will connect the mount directly to my imaging laptop computer using the PWI software.
There are 2 autoguiding ports for flexible cable management configurations, so I officially have no excuse for a tangled mess of wires with this mount. The 12V DC power input barrel connector is threaded, a feature I am seeing more and more with newer mounts.
If you have ever jostled the power input on your mount and lost connection while imaging (like I have several times), you'll definitely appreciate this subtle upgrade.
The internal real-time clock saves the time and observation site information you have entered even after the mount has been powered off.
I look forward to testing the mount control and plate-solving abilities of the ZWO ASIair with the CGX-L. Because this NexStar mount supports the INDI protocol, I can tap into some of the handy functions on the ASIair app from my tablet.
What I Really Like So Far
The instruction manual is very helpful with detailed information, photos, and diagrams. One such nugget of valuable information is Celestron's advice about orienting the mount so that the counterweight shaft is directly over a tripod leg. Naturally, this orientation provides better stability, but also creates more room directly behind the telescope.
The CGX-L contains a not-so-secret 8mm Allen wrench underneath the bottom carry handle. It’s little touches like this that let you know that the team at Celestron spent a lot of time thinking oabout the overall user experience.
The counterweight bar has a high-end brushed-nickle looking finish. It is also very long and heavy, with serious looking threaded stop nut at the end (toe-saver).
The DEC and RA clutch levers are extremely solid and secure. They are finished in Celestron orange, contain the iconic “C”, and even reveal a subtle sparkle sheen when viewed under the right lighting. They are substantial in your hand and feel secure when you lock them into place. There is no questioning whether the clutch has engaged or not.
Attaching the 22-lb counter weight to the mount.
Mount Type: Computerized Equatorial
Load capacity: 75 lbs
Height adjustment range: 35.75" - 52.75"
Tripod Leg Diameter: 2.75")
Latitude adjustment range: 3° - 65°
Mount Head Weight: 52.6 lbs
Accessory Tray: Yes
Tripod Weight: 46.2 lbs
Counterweight: 1 x 22 lbs
Slew Speeds: 9 slew speeds
Tracking Rates: Sidereal, Solar and Lunar
Tracking Modes: EQ North & EQ South
Dovetail Compatibility: Dual saddle plates
Number of Auxiliary ports: 4
Autoguide port: Yes, 2 ports
USB Port: Yes, input for Mount and Hand Control
Power Requirements: 12V DC, 3 amps
Motor Drive: DC servo motors
Alignment Procedures: 2-Star Align, 1-Star Align, Solar System Align, Last Alignment, Quick Align
Periodic Error Correction (PEC): Yes
Computerized Hand Control: 2 line x 18 character backlit LCD, USB 2.0 port for PC connection
NexStar+ Database: 40,000+ objects
Software: PWI Telescope Control Software, Celestron's Starry Night Special Edition Software, SkyPortal App
Total Kit Weight: 120.8 lbs
CGX-L Equatorial Head
1 x 22 lbs counterweight
NexStar+ Hand Control
DC Power Cable
8mm Allen wrench
I hope you have enjoyed this overview and first look at the Celestron CGX-L computerized GoTo mount. I've had this amazing piece of equipment in storage for two months now, and anxiously await an opportunity to put it to work under clear skies this month.
You can expect a full review of this observatory grade telescope mount in the coming months. I will discuss the astrophotography performance of the mount from a practical point of view. This includes autoguiding performance, tracking accuracy, the NexStar control system and general use in the field.
Are you hoping to capture a photo of the total lunar eclipse on January 20, 2019? If so, you are not alone. Amateur photographers and astrophotography enthusiasts around the world will do their best to take a pictures of the lunar eclipse in January using a wide variety of camera equipment.
These days, every full moon and lunar eclipse has some sort of epic name attached to it, and the total lunar eclipse in January 2019 is no different. The media has nicknamed this astronomical event the Super Blood Wolf Moon 2019. That's right, don't forget to add the "Super".
Catchy names aside, a total eclipse of the moon is a truly breath-taking astronomical event that anyone can appreciate. Over the years, I have photographed a number of total lunar eclipses, and I plan to do so again on January 20, 2019. There are many ways to photograph the total lunar eclipse this January, but for the best results I recommend using a DSLR camera and a small refractor telescope on a tracking mount.
The total lunar eclipse on January 20-21, 2019 is the only total eclipse of the moon in 2019 around the world, with a partial lunar eclipse happening on July 16 in isolated parts of the world.
To capture a detailed portrait of the moon like the image above, a long focal length and a tracking equatorial mount are required. However, it is also possible to produce a comparable close-up image using a digital camera or smartphone through the eyepiece of a non-tracking telescope using the eyepiece projection method.
In this post, I'll share some tips for photographing this celestial event using both basic and advanced astrophotography equipment.
What is a Lunar Eclipse?
Do you understand why a lunar eclipse happens? There are two types of lunar eclipses: partial and total. I am happy to say that the event on January 20-21 is the extra exciting one.
As you know, the Earth orbits the sun, and the moon orbits the Earth. During a total lunar eclipse, the Earth is sitting directly between the sun and the moon. Although the moon is being covered in Earths shadow, some sunlight still reaches the moon.
When the moon enters the central umbra shadow of the Earth, it turns red and dim. This distinctive "blood" color is due to the fact that the sunlight is passing through Earth's atmosphere to light up the disk of the moon.
A diagram of what happens during a total lunar eclipse - NASA
Unlike a solar eclipse, observing a total lunar eclipse is completely safe to do with the naked eye. This natural phenomenon can be enjoyed without the aid of any optical instruments, although binoculars can really help to get an up-close view of the action.
Where and When will it Happen?
The total lunar eclipse will take place on January 20-21, 2019, with the total phase visible from North and South America. From my vantage point in Ontario, Canada, the maximum eclipse will occur at 12:15am on January 21. To find out when the total lunar eclipse will take place from your location, you can check out this eclipse map on Timeanddate.com.
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There are 7 stages of a total lunar eclipse, and many amateur photographers like to capture the event in each stage. This can later be made into a composite photo showing the transition of the moon as Earth's shadow covers it. A time lapse video is another excellent way to capture each stage of the eclipse.January 2019
The maximum eclipse stage is when most photographers want a great shot. This is when the the moon turns "blood" red and the surrounding night sky becomes much darker from our point of view on Earth. It is an unforgettable experience for those lucky enough to witness this moment.
An interesting thing happens when the moon is completely eclipsed by the shadow of Earth. Not only does the moon turn to an eerie reddish hue, but the stars and constellations surrounding the moon begin to appear as they would on a moonless night. Capturing a scene like this requires careful planning and execution.
Tips for Photographing the Total Lunar Eclipse
There are numerous ways to photograph a lunar eclipse, but here are 5 methods I techniques I suggest you try out:
Point-and-shoot digital camera through a telescope eyepiece (eyepiece projection)
Smartphone camera through a telescope eyepiece
DSLR camera and wide angle lens on a stationary tripod
DSLR camera and telephoto lens on a tracking mount
DSLR camera attached to telescope (prime focus) on a tracking mount
Dedicated astronomy camera attached to telescope and tracking mount
A photo of the "Super Blood Moon" eclipse I captured from my backyard in 2015
All of the methods described above are capable of incredible lunar eclipse photos. However, the ones that leverage the full manual control of a DSLR or dedicated astronomy camera will have more creative control over the types of shots available.
Wide-angle nightscape images that include a large portion of the night sky including an eclipsed moon can be done using a DSLR and tripod. For a 30-second exposure, a tracking mount is not necessary. At a focal length of 18mm or wider, star trailing will begin to show after about 20-25 seconds, so just keep that in mind.
To capture the stars and constellations in the night sky, an ISO of 800 or above is recommended. However, this exposure will likely record the eclipsed moon as a featureless ball of light.
To properly capture both the starry sky and a detailed moon, you will need to capture exposures of varying lengths and blend them together into a composite image. This is because the moon is much brighter (even while eclipsed) than the surrounding starry sky.
A composite image can be made be masking the area of your night sky exposure, and blending in a shorter exposure of the moon with surface details. This technique will take some time and experience to master, but the results can be amazing.
A telescope can provide an up-close view of the eclipsed moon, and will allow you to take pictures of the moon using your camera or smartphone. The prime focus method of astrophotography is best, as the camera sensors focal plane is aligned with the telescope. You can directly attach a DSLR camera using a T-Ring adapter to utilize the telescopes native focal length.
A DSLR camera and T-Ring Adapter attached to a telescope
The prime focus method requires that the telescope tracks the apparent rotation of the night sky to avoid any movement in your shots. To learn more about the process and equipment involved for deep-sky astrophotography, have a look at a typical DSLR and telescope setup.
If your goal is to capture an up-close view of the moon during the eclipse, there are many benefits to this technique. A small refractor telescope will have the adequate amount of focal length (magnification), offer precision focus, and a stable base to attach to an equatorial telescope mount.
To record the lunar eclipse with a DSLR camera, no filters are necessary. A stock DSLR camera is best as the additional wavelengths available with a modified camera are unused in moon photography.
Camera settings used for my lunar eclipse photo
Without a tracking equatorial mount, a 2.5 second exposure like the one above is impossible. Even 1-second of movement at this focal length will record a blurry image if the telescope or lens is not moving at the same speed as the moon.
The benefit of shooting a longer exposure during the maximum eclipse, is that you also record the starry sky behind the moon. To do this in a single exposure on a normal full moon is not possible as the dynamic range is too wide.
A dedicated one-shot-color astronomy camera is more than capable of taking a brilliant photo of the eclipse as well. The computer software used to control these devices have countless options to control the Gain and exposure settings of theses cameras.
For projects like this, I personally enjoy the freedom and simplicity of a DSLR. Camera settings such as ISO, exposure and white balance can easily be changed on-the-fly as the eclipse is taking place.
Using a Telephoto Camera Lens
A telephoto camera lens with at least 300mm of focal length will also work well. At longer focal lengths like the ones necessary for a close up of the moon, you must use a fast exposure to capture a sharp photo of the moon. This is because the Earth is spinning, so you're essentially trying to photograph a moving target.
The image below was captured using a Canon EOS 70D and a Canon EF 400mm F/5.6 Lens.
The final stages of the partial eclipse phase are challenging to photograph because there is a bright highlight on a small portion of the moon. For the photo below, the camera settings included an ISO setting of 6400, and a shutter speed of 1/8.
A tracking telescope or camera mount such as the iOptron SkyGuider Pro (pictured below) is recommended. An equatorial mount that is polar aligned with the rotational axis of the Earth will allow you to take longer exposures, and get more creative with your camera settings.
Owners of astronomical telescopes for astrophotography usually own a GoTo equatorial mount. This allows the user to enter any celestial object into the hand controller, and the mount will automatically slew to that object once it has been properly star aligned.
An iOptron SkyGuider Pro camera mount with a DSLR and 300mm Lens attached
The key to capturing details of the moons surface in your lunar eclipse photo is reach, and exposure. By this, I mean that you need enough magnification to show the detailed craters of the moon's surface, and a fast enough shutter speed to not blow out any of the highlights in your image.
To do this, a precise exposure length must be used. One that preserves the data in your image while also bringing enough of the shadowed areas forward is ideal. For my photos, I found an ISO of 200 and an exposure of 1/200 to work quite well. This was enough to showcase a starry sky behind the eclipsed moon.
I use Adobe Photoshop to process all of my astrophotography images, including photos of the moon and our solar system. Adobe Camera Raw is a fantastic way to edit your images of the lunar eclipse because it gives you complete control over the highlights and color balance of your image.
Adobe Camera Raw offers powerful tools to edit your photos of the Total Lunar Eclipse
With the camera connected to the telescope (prime focus astrophotography), experiment with different exposures and ISO settings in manual mode, using live-view to make sure you have not under/overexposed the image.
The shortest exposures will only be useful during the partial stages of the lunar eclipse, as the lunar eclipse is beginning and ending. As I mentioned earlier, this is a challenging phase of the even to capture in a single shot, as the shadows and highlights of the image are from one end of the spectrum to the other.
When the moon enters totality, you will need to bump up your ISO, and/or your exposure length to reveal the disk of the moon as it becomes dimmer. Use a timer or external shutter release cable to avoid camera shake if possible. Ideally, you'll keep the ISO as low as possible for the least amount of noise. With an accurately polar-aligned tracking mount, exposures of 2-5 seconds will work great.
Using a Smartphone or Point-and-Shoot Camera
Another way you can photograph the moon is to use the eyepiece projection method of astrophotography. To do this, you'll simply position your digital camera or smartphone into the eyepiece of the telescope. This method usually requires a far amount of trial and error, but you may be quite surprised with your results.
An eyepiece smartphone adapter may help to steady your shot of the lunar eclipse. Although you'll have much less control over exposure and record less detail, this technique can be used with a non-tracking telescope such as the Apertura AD8 Dobsonian I reviewed in late 2018.
The moon is one of the few subjects that is easy to photograph with a non-tracking mount, although the transition phases of the eclipse will be more difficult. I recommend capturing the lunar eclipse during its maximum phase if you're using this method. You likely won't be able to capture a well-exposed image using the cameras auto-exposure mode.
Experiment with your cameras manual settings that allow for variations in shutter speed.
Without Using a Telescope
If you are simply using a point and shoot camera, or a DSLR and lens on a tripod, you can still take photo of the lunar eclipse. This is often a great way to capture the landscape and mood of the moment. The photo below was captured back in October 2014 using a CaDSLR Canon EOS 7D and a 18-200mm lens.
The wide angle tripod shot was photographed at 18mm, while the inset image was captured at the lenses maximum focal lengh of 200mm.
Just like I mentioned when using a phone camera, you'll want as much manual control over the camera settings as possible. "Auto" mode, flash, and autofocus won't work on a photo of the total lunar eclipse. Adjusting individual parameters such as exposure length and ISO is essential when photographing objects at night.
Practice taking shots at night beforehand, so that you are ready when the eclipse happens. Ideally, find a location that includes some interesting foreground and background details to capture a dramatic scene on the night of the event.
I hope you enjoy the total lunar eclipse in January with your friends and family. If the weather cooperates, I will be photographing the event from my backyard using a DSLR camera and telescope.
If you watched my video about Comet 46P Wirtanen, you many have noticed that my imaging gear included a Canon EF 300mm F/4L USM Lens. This may have seemed a little odd to those that are used to seeing me use a telescope for astrophotography, but a camera lens like this can be a great way to capture deep sky images.
Over the years, a lot of people have asked me why they should invest in a new telescope when they already own a high-quality telephoto camera lens with a comparable focal length. After all, a prime lens like the Canon EF 300mm F/4L isn't cheap, and its got some seriously impressive optics.
So, if you've already got a lens like this in your kit, you should definitely try using it for astrophotography before investing in a new telescope.
Canon 300mm F/4L Lens for Astrophotography
Make no mistake, a telescope designed for deep sky astrophotography has many advantages in terms of deep sky astrophotography. Specialized features such as a robust dual speed focuser, light baffles, and the ability to easily accommodate astronomy cameras and autoguiding systems to name a few.
But if you've been into photography for a while, there's a good chance you'll already own some camera lenses that are perfect for astrophotography. The secret is, to leverage the tracking abilities of an equatorial mount that allows you to capture long exposure images of the night sky without star trailing.
In this post, I'll show you how I managed to capture an impressive portrait of the Orion Nebula using a 300mm camera lens from my backyard in the city. I'll discuss the filter I recommend, the camera settings I use, and the share the process of capturing long exposure images on a tracking mount.
My Canon EF 300mm F/4L USM Lens
Canon 300mm F/4L (Non IS)
The camera lens I am using is a first generation Canon EF 300mm F/4L (Non-IS). This is an old L-series lens from Canon that does not include Image Stabilization, but does include the ring type USM motor. Features like IS and autofocus won't work for astrophotography, so older prime (non-zoom) lenses like this are a great value in the used market.
It's quite useful to have prime lenses at different focal lengths in your astrophotography kit. You'll be able to capture a wide variety of targets from large open star clusters to emission and reflection nebulae like Orion.
I purchased my 300mm F/4L used, and drove a fair distance to meet the seller. The lens was originally intended for bird photography, which I still enjoy today with a 1.4 extender attached for more reach. The native focal length of 300mm and widest aperture are a better configuration for astrophotography purposes.
The 1.4 x Canon teleconverter introduces chromatic aberration, and I lose a full stop of light (F/5.6). This is not usually an issue in my daytime photography images, but it's out of the question when photographing stars.
Using the Canon 300mm F/4L lens on a crop-sensor DSLR (APS-C) camera like my Rebel T3i will effectively create a narrower field of view than a full-frame camera does. This creates an equivalent focal length of 480mm with the crop factor applied (1.6X), which is important to consider when framing up an astrophotography target.
Using a simple FOV (field of view) calculator, you can get a preview of the expected image scale of your target. As you can see, the Canon 300mm F/4L and Canon EOS 600D combo frame the Orion Nebula and Running Man nicely.
The Field of View using a 300mm Camera Lens and APS-C Sensor DSLR
Most of the astrophotography telescopes I recommend for beginners hover around the 400mm to 700mm focal length mark, so this camera lens is quite comparable. Also, the Canon EF 300mm F/4L Non IS contains two UD (Ultra low dispersion) lens elements similar to the construction of an apochromatic refractor.
The rather fast optics of this lens (F/4) is advantageous for night photography, as its widest aperture will allow plenty of signal (light) to be collected in each shot. For comparison, my Sky-Watcher Esprit 100 APO has an F-Ratio of F/5.5.
When it comes to acquiring astrophotography data for a healthy signal to noise ratio, a camera lens with a fast aperture is recommended. This is why camera lenses like the Rokinon F/2.8 and Canon F/1.8 are excellent choices for astrophotography.
Focusing the lens
Finding a precise focus using a camera lens is much more difficult than it is with a telescope. Rather than using a smooth dual-speed micro focuser, you have the challenging task of using the rather sensitive focusing ring on the lens (in manual mode of course).
It's best to point the camera towards a bright object (not a star) to find the initial focus. The Moon, or a distant streetlight will do. Once you have it dialed in using the lenses widest aperture (F/4), you can then aim the lens at a bright star in the night sky using your cameras highest ISO setting.
From here, it's a matter of trial and error until you find the sweet spot. Once you've found it, be very careful not to bump it out of focus when slewing to your target. You can always fine tune the focusing ring on your deep sky target using short test exposures after.
The Camera: Canon EOS Rebel T3i
This Rebel T3i (600D) camera has been "modified" for astrophotography, which isn't nearly as complicated or technical as it sounds. I've basically removed an internal filter that blocks certain wavelengths of light from being recorded on the sensor (I didn't modify this 600D myself, it was done by a professional).
The stock internal IR cut filter found in DSLR cameras like the Canon Rebel T3i creates "normal" looking daytime images, but can hold your astro images back. If you own a DSLR camera that you want to use for astrophotography, look into getting it modded. I waited almost 4 years before making this upgrade, and it significantly improved my astrophotography images.
This modification will better showcase the rich areas of hydrogen gas in the Orion Nebula. For certain deep sky targets (such as the California Nebula) a full-spectrum modified DSLR is essential for a respectable image.
My Full Spectrum Modified Canon EOS Rebel T3i
The Orion Nebula isn't one of them! A stock DSLR camera can capture exquisite images of this reflection/emission nebula with beginner-level equipment.
To photograph Messier 42, I'll shoot a series of 1.5-minute exposures at ISO 400. The images will collect a healthy amount of signal (or light) on this nebula and the surrounding area. With the temperature hovering around zero on the night of acquisition, I benefited from a cool camera sensor that didn't produce nearly as much noise as I experience in the summer.
Covering the sensor is an Optolong L-Pro filter. This broad spectrum filter is an excellent choice if you are looking to produce natural looking astrophotography images in the city. Light pollution is a big problem for many amateur astrophotographers, and filters like the L-Pro can make your life easier.
This filter clips-into the camera body, and fits neatly underneath the camera lens. Being able to use this filter with either a camera lens or telescope attached is a real bonus. I have also used this filter underneath the Rokinon 14mm F/2.8 lens for some wide angle shots of the night sky from home.
The Camera Mount: iOptron SkyGuider Pro
The iOptron SkyGuider Pro is the perfect solution for those looking to get started in astrophotography with a DSLR camera and lens. It's a highly portable, non-nonsense astrophotography mount that allows you to start tracking the movement of the night sky for long exposure imaging. With the counterweight attached, it can handle heavier lenses like this 300mm F/4L, and even a small telescope like the William Optics Z61.
For this mount to be effective, it must be accurately polar aligned. In the northern hemisphere, we have the advantage of being able to use the north star, Polaris, to help us align with the polar axis of the Earth.
The iOptron SkyGuider Pro Camera Mount
To start tracking, its a simple as turning the SkyGuider on, with the mode set to sidereal rate. After that, the camera mount slowly matches the apparent rotation of the night sky, and my long exposure images record pin-point stars without trailing.
The SkyGuider pro includes an illuminated reticle that you can use as a guide to align the mount. This make it really easy to get your alignment just right - which is critically important for astrophotography. Polar alignment and balance will make the biggest impact on your images.
The farther off you are in either area (balance and polar alignment), the shorter your exposure times will need to be. With a sound polar alignment and a careful balance, unguided exposures of 3 minutes or more are no problem on the iOptron SkyGuider Pro mount.
Locating Objects with the SkyGuider Pro
To locate and frame a deep sky target using this mount, it must be done manually (no GoTo functionality). For bright targets like the Orion Nebula, this is extremely easy, as I can line up the target using the viewfinder on my DSLR camera. For faint targets, or when using a narrowband filter, you may need to take a number of test exposures to get it framed just right.
I personally have the SGP mounted to a lightweight carbon fiber tripod. This is a highly portable configuration, but it's likely a little too flimsy for folks that want a rock-solid platform. Consider using a more robust aluminium tripod with this mount.
The Target: Orion Nebula
The bright moon certainly isn't helping me capture the faint dusty details surrounding Orion. Luckily, M42 is such a bright deep sky object that it can be enjoyed in less than perfect conditions. I've photographed this target so many times, and it never gets old.
It's a spectacular target to test new equipment on, because you are bound to get a rather impressive image no matter which approach you take. The light pollution filter used (Optolong L-Pro) did a great job of reducing the unwanted artificial light present in my backyard, allowing the natural star colors to shine through.
To create my final image, I've stacked the individual exposures together using a free software called DeepSkyStacker. The resulting was then brought into into Adobe Photoshop for further processing. If you want to learn how I process my astrophotography images, have a look at some of the image processing tutorials I've shared in the past.
The Orion Nebula captured using a Canon EF 300mm F/4L Lens (Click for larger version)
The Bottom Line
As you can see in my image above, the stars are sharp and free of chromatic aberration (color fringing). This is a testament to the high quality optics of the 300mm F/4L lens, and an important factor to consider when choosing a camera lens for astrophotography.
Capturing sharp, accurately colored stars is the ultimate challenge for optical equipment, and the Canon EF 300mm F/4L passes with flying colors. The field is also extremely flat, another trait of only the best camera lenses.
A prime telephoto camera lens like the Canon EF 300mm F/4L is a great way to capture deep sky astrophotography images, as long as you've got a way to track the night sky for each shot. The wide field of view is very forgiving, meaning autoguiding isn't necessary for a successful long exposure image.
Whether you're using a camera lens, telescope, or a pair of binoculars. I hope you're able to get out and appreciate the impossibly beautiful history of our universe that shines above our heads this season.