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If you take long exposure of dim object, bright satellite passing in front of it will saturate signal and there will be nothing to recover. To avoid that you ne
by terramex 6y ago
If you take long exposure of dim object, bright satellite passing in front of it will saturate signal and there will be nothing to recover. To avoid that you need to track all the satellites and split one long exposure into multiple shorter ones - but that multiplies read noise accordingly.
- system2 6y agoThis is why I take 500+ images and process them. I don't think the moving satellites would cause any harm to long exposure deep space photography. I agree if you take 30 pictures, it could be a problem.
- terramex 6y ago> This is why I take 500+ images and process them. If you do 500 exposures you get 500x read noise of the sensor mixed with signal. Modern CCD and CMOS sensor have low read noise (compared to thermal and shot noise) but not zero. For scientific observations of faint objects long exposure times on order of hours are necessary, for amateur astrophotography you can just go with multiple exposures.
- mkj 6y agoThanks for the explanation, I didn't realise there was a per-exposure noise component.