I’ve recently started doing some planetary imaging, and while I am far from being an expert at the process, I have worked out a general method that can produce some beautiful images from less than ideal equipment. I’m currently using a Celestron C6 SCT on a manual Explore Scientific Twilight 1 mount. For the camera side, I’m using a Canon SL2 DSLR, usually with a thread on barlow lens or two. The two barlow lenses I’m currently using are a 1.6x and 2.0x William Optics lenses designed for use with their binoviewers.
To image planets, you don’t want to take individual photos. Instead, you want to take video, and then pick out the best individual frames that can be combined to produce the best image. Atmospheric turbulence will vary the image quality from frame-to-frame, so by taking video for several minutes you can generate thousands of image frames, and then pick out the best ones to use to produce the final image.
I’ve used different camera settings, and haven’t decided what the best option is at this point since I’ve had similar results with most of the settings. With the 29.7fps HD setting on the Canon camera, you can also use a 3-10x digital zoom. Without using the digital zoom, the 1080p image will essentially combine multiple pixels into one to produce the final video image. A 3x digital zoom gets you closer to a 1-to-1 pixel ratio which may be helpful for better processing results. At the same time, using the 60fps HD video settings, while not allowing the use of a digital zoom, allows you to get more individual image frames, which can help in the final processing as well. The 640x480 VGA mode is available but that makes it harder to track the planet manually.
Eventually, I plan to upgrade to a tracking mount of some type, and probably a dedicated imaging camera, but even with the current setup I’ve been surprised at the results. To process the raw mp4 video files coming out of the DSLR I used a three-step process. First I use PIPP to convert the video to AVI format and to crop the video to a smaller frame that also has the planet centered in each frame. Besides making the video format readable with the next piece of software used, AutoStakkert, the cropping and centering done by PIPP speeds up processing in AutoStakkert.
After selecting a file in PIPP, make sure to check "Planetary" under "Optimise Options For:"
You can edit your cropping window as needed. By cropping the image and removing a lot of blank space, you can speed up your processing time in later steps. Make sure to preserve some black space around the planet, however.
Then, process the data to create the cropped AVI file.
Once the processed AVI file is ready, I can open that up in AutoStakkert, run the analyze function, and decide how many frames I want to stack based on the image quality of each frame. Since AutoStakkert sorts the frames from best to worst, it is easy to use the slider to figure out at what point the images start to go off the rails and become more hurtful than helpful. Still, since stacking the frames in AutoStakkert is fairly quick, it is a good idea to produce multiple stacked images with varying amounts of frames stacked. It might turn out that combining 30% of the frames produces the best results with one video file, while 75% provides the best result with another. Generally, it seems that planets like Saturn are aided by more frames, while planets like Mars need fewer, though my total experience is limited, so that may not hold long-term.
Once you decide how many frames to stack, you also need to determine how many points on the image to use for stacking. You can set, say, 40 image boxes over the planet, either using the automated feature (which I usually do) or manually pick the points of interest. The magic of AutoStakkert is that it will find the best frames for each of those particular little boxes, stack those, then stitch all the little boxes together to produce the final image. In that way, you maximize the final image quality.
The image after stacking in AutoStakkert:
Once a stacked image has been produced, that can, in turn, be opened up in Registax. While Registax can also stack video frames, AutoStakkert does a better job. However, Registax has an impressive wavelet sharpening tool that can dramatically improve the image coming out of AutoStakkert. The best wavelet settings will vary for each image and are mostly a trial and error process. Generally, I increase the sharpness setting and then the denoise setting of each wavelet, then go back and play with the sliders, then adjust the sharpness and denoise settings. I’ve used different settings on every image I’ve processed, but you can see the settings I’ve used for this particular Saturn image below.
Note that I clicked on "Flip and Rotate" to flip the image around for the final version.
Here is the final image of Saturn after the raw video processed in PIPP, AutoStakkert, and Registax. The whole process can take less than 20 minutes, though you can spend a lot of time playing around with the sharpening in Registax, as well as other features like the RGB settings, etc.
I should note that all of this software is available for free. Also, while all of the software is in windows format, I’m currently using all of them on a 12” Macbook, using WineBottler to run them in Windows emulation mode. On my larger 15” MacBook Pro, I have a full version of Windows 10 running in VMWare Fusion, and I can then install software directly in Windows and get a full windows experience in that manner. Both allow me to use these software products as well as my Mac software I use at the same time. I’ll try to do another blog post and video showing how to install this software on a Mac using WineBottler since that might be helpful for some people.
Here are links to all of the software used as well as the telescope and camera items I used.
WineBottler: http://winebottler.kronenberg.org
PIPP: https://sites.google.com/site/astropipp/
Autostakkert: https://www.autostakkert.com
Registax: https://www.astronomie.be/registax/
Celestron C6: https://amzn.to/2CZF1t9
Twilight I mount: https://amzn.to/2R4p0oP
Canon SL2: https://amzn.to/2R6Xwih
2.0x WO Barlow: https://amzn.to/2CZhLeY
Canon T2 adapter: https://amzn.to/2R7LhSr
T2 to 1.25” adapter: https://agenaastro.com/baader-1-25-nosepiece-t-2-adapter-t2-14-2458105.html