![]() ![]() When you do that, you become photon shot noise limited, and read noise is effectively dealt with by a simple offset (i.e. More specifically (and this involves more complicated math), you want to get your signal strength high enough in each sub that you totally swamp read noise with your "background sky". So, with the math out of the way, what does it mean? It means that getting the highest signal per sub is best. The signal is combining as well, and the signal grows faster than the read noise, but read noise does not average out like everything else, so you have to be careful with it. It's the one kind of noise you have to watch out for, as if you combine lots of frames (115, for example) the read noise starts to add up, while all the rest of the noise averages out. While everything else is scalar, R is squared, so it compounds as you combine more and more frames. Notice here.R is SQUARED in the square root term. Here's the math (simplified a bit, it ignores other factors that I don't want to get into with you guys yet): Thing about read noise, it adds in a certain way, and it does NOT average out like dark current noise or photon shot noise. Noise does average out, if it is the right kind of noise. One piece of advice: Try to get longer exposures, rather than stacking tons of short exposures. Great stuff, guys! Your really progressing! ![]()
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