Quote:
Originally Posted by Somnium
from my understanding, by oversampling you are dividing any given number of photons into smaller buckets without gaining any true resolution due to seeing restrictions. this results in an overall reduction in the sensitivity of the sensor.
say you were using 5 micron pixels, you would need 4 times as much time to gain the same signal from a 10 micron pixel.
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FWIW, that's how I see it as well. with the same fill factors, 10 micron pixels will get exactly 4x as many photons as 5 micron ones for a uniform illumination and that is the basis for considerations of sampling - you need to get the pixels just small enough to get all the detail - and not one jot smaller.
Granted you can bolt any cam onto any scope and get reasonable images. But if you want to get the best resolved image in the shortest possible time, you need to match your sampling to your seeing convolved with the scope psf (about 2.75 pixels per FWHM seems to be best). Getting it wrong can be dramatic - a 1.4x mismatch could make a 2x difference to the required imaging time, with no better detail.
If you oversample, the results will not be any better resolution than properly sampled, but the SNR will be worse and the image will look blurry because there will not be any abrupt edges and stars will look big (it won't actually be any blurrier than a well sampled image, but you will perceive it as blurrier unless you downsample it). With a bit of care, you could oversample and then use software binning after the event to get back some SNR and sharpness perception - that would give you true high res in exceptional conditions, with the ability to throttle back under average conditions. I guess this is what you were getting at with the "work out even in the wash" comment?