Quote:
Originally Posted by Solitarian
Thanks raymo. I wasn't sure if there was a point of diminished returns, so on a good night it would be worth putting the time in to gather extra images, that's good to know.
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Because in each frame you have a fixed noise component (mostly the sensor read noise in the camera) the extra signal-to-noise you gain increases with the square root of the number of subs you take. So if you take 4 you double your SNR (signal to noise ratio), but taking 25 only gives you 5 times the SNR, 100 subs-> 10x...
So taking more subs is always good, but in terms of just increasing the SNR more exposure in each sub is more effective - until you max out the signal in your sensor (stars are bright and max out quickly) or the background brightness of the sky is the only thing you're continuing to enhance - the so-called "sky fog".