The Canon EOS R5 arrived just in time to capture the spectacular night show Comet NEOWISE was providing. Sorry that the noise test results for this camera were delayed by a day, but this was an opportunity I couldn't pass up (at least I waited until after the R5 review was finished to process this image).
The first challenging comet photography decision to make was the desired composition. Including landscape or filling the frame with the comet were the options, and the latter option was chosen. After determining that NEOWISE would nearly fill a 200mm frame, the Canon EF 200mm f/2L IS USM Lens was the chosen lens. The wide f/2 aperture is excellent for use in the dark, and the impressive sharpness of this lens at f/2 means that stars (over 7,000 software-recognized in this frame) remain pin sharp.
The next decision was whether or not to utilize an equatorial tracking mount. A 200mm lens directed at the comet's location in the sky with an ultra-high-resolution imaging sensor behind the lens meant that relatively short images, about 2 seconds, were the limit before star trails became noticeable. On the equatorial mount, 13-second images showed no motion, and this was the option taken. Though the 200 f/2L is rather heavy for the Sky-Watcher Star Adventurer Astro Package, this affordable mount along with the Star Adventurer Mini Latitude (EQ) Base and Counterweight Kit were up to this task. With that much weight riding on it, this mount works best on a solid tripod, and the Robus RC-8860 Vantage Carbon Fiber Tripod was a perfect choice. B&H had just sent me a Robus RTH-1050 Ball Head. It works great, so that option was mounted on the Sky-Watcher.
The R5 was set to manual exposure with 13 seconds, f/2, and ISO 1250 selected. High-speed continuous shooting in 1st curtain shutter mode (this is where I learned that the full electronic shutter does not allow exposures longer than 0.5-seconds). A Canon Timer Remote Controller TC-80N3 was plugged in, and its shutter release was locked on. With the Star-Watcher Star Adventurer polar aligned, the lens framing the comet, including the extensive tail that was not readily seen in the viewfinder, and the camera continuously capturing images, I walked away, watching the comet through binoculars and enjoying a bowl of ice cream.
Despite the night having a clear forecast, clouds showed up in the frame a significant amount of the time prior to the comet setting (while the rest of the sky remained clear). Fortunately, 45 images captured contiguously were able to be made cloud-free with slight cropping. 45 x 13 seconds = 9.75 minutes of exposure, long enough to produce a nearly noise-free image and long enough to capture the color in the ion tail.
While the air traffic is not currently as strong as usual, more satellites than ever are in the sky. Nearly every image had at least one satellite, and some photos had as many as three satellites streaking through. I opted to crop out the clouds before processing the RAW image into 16-bit TIFF files and then removed the streaks using the healing brush tool in Photoshop.
The next task was to stack the images. Stacking comet images is a level of challenge higher than stacking star images due to the comet moving at a slightly different rate than the stars. I know, it is the earth that moves the most, but from an earth-bound perspective, the stars and comet are moving. Stack the comet, and the stars become streaked. Stack the stars, and the comet is stretched. Fortunately, some very smart people created DeepSkyStacker software with an option to align both the comet and the stars.
DeepSkyStacker does a superb job, but you would not know that when looking at the default image created. The low-contrast 32-bit image requires "stretching", contrast significantly increased with colors pulled out. The only adjustments made to this image were contrast (levels and curves to stretch the low contrast 32-bit stacked image), saturation (+10 and -60 in PS), and a white balance adjustment (cooled the image slightly).
I love NEOWISE's colored ion tail, pushed away from the sun by solar winds and separated from the dust tail. BTW, the name NEOWISE uses all capital letters because it is an acronym, named after the device that discovered it.
Now, NEOSWISE is gone, effectively, forever. Comet NEOWISE was awesome but will not be seen again for another 6,800 years. Hopefully, another comet will entertain us in the night sky long before that.