Best amount of images for stacking

Started 4 months ago | Questions thread
imperial
OP imperial Regular Member • Posts: 117
Re: Best amount of images for stacking

EricTheAstroJunkie wrote:

imperial wrote:

I came across a video of a Astro-photographer saying 25 light frames and 2 dark frames are the best and anything more yields little improvement to overall milky way IQ.

Is this true? And what are your experiences with stacking images?

No, it's 100% incorrect and a completely arbitrary statement to be making, I would definitely ignore whatever advice that astrophotographer is given because they are making completely baseless claims.

As the others have said, the reduction in noise is proportional to the square root of the number of images stacked. A LOT of factors will go into what kind of visual result comes from stacking 10, 25, 250, or 1000 subs so saying "there's no reason to stack more than 25 exposures" is a completely pointless number. And no matter what 2 dark frames is an abhorrent number of dark frames to stack, you should not stack anything less than 30 dark frames IMO due to the nature of frame to frame variation as well as slight temperature shifts which can impact noise distribution. It is very easy to screw up dark frames and have a negative impact on your final image quality/calibration, using only 2 dark frames would probably guarantee screwing up your calibration and actually adding noise to your image. There are a lot of deep discussions about the number of frames to stack for each type, a lot of great comparisons showing the increase in SNR and detail with more sub exposures stacked. The takeaway is simple for beginners, the more integration time and the more high quality exposures you can stack the better. For ultra wide angle imaging (say, wider than 100mm focal length) with a very fast lens you probably could get away with stacking an hour's worth of exposures. I don't recommend stacking anything less than 3 hours unless you only stacking for Milky Way/Nightscape purposes. For DSO imaging I tell people to aim for 6 hours+ of integration time.

Wow, thanks. I've learned something but I did not expect the depth of it.

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