Will stacking more exposures reveal more detail in my Whirlpool Galaxy image?
Asked 3/27/2020
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I’m new to astrophotography and photographed the Whirlpool Galaxy (M51) with a Sony A77 II and Sigma 18–300mm lens at 300mm on a Move Shoot Move tracker. I shot 103 light frames at 1 minute each, f/6.3, ISO 3200, plus 30 darks and 31 bias frames, then stacked them in DeepSkyStacker and did light processing in Lightroom.
Will adding another 100 or so exposures noticeably improve the result? I’m mainly wondering whether more stacking will bring out more detail or just reduce noise, and whether my current setup is already close to its limit for this target.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
6y ago
2 Answers
7
Stacking more images reduces noise to signal ratio, but don't add resolution or details.
In order to enhance resolution, my advice is to use a prime lense, instead of a zoom one. Even if it has less focal length.
In my personal experience, I get more details with a 80mm prime than with a 55-250mm at 200mm
Originally by user83011. Source · Licensed CC BY-SA 4.0
user83011
6y ago
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More stacking will mostly reduce noise, not increase true resolution. So yes, another 100 frames can help the image look cleaner and may let faint detail stand out a bit better, but it won’t suddenly reveal much finer structure in the galaxy.
Stacking improves signal-to-noise ratio, and slight frame drift can sometimes give a small sub-pixel benefit, but the main limits on detail here are focal length and lens sharpness. At 300mm, M51 is still a fairly small target, so to capture significantly more detail you generally need more magnification—typically a longer, sharper lens or a telescope.
Your calibration frames are useful and worth continuing.
If your goal is better image quality with this setup, the biggest gains are likely to come from:
- more total integration time for lower noise
- careful processing
- a sharper lens, ideally a prime rather than a superzoom
- longer focal length if you want more galaxy detail
So: more frames will help somewhat, but they won’t transform the image the way a longer focal length or sharper optic would.
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