Quote:
Originally Posted by ericwbenson
Not quite, the lights and darks could still match in length (e.g. 10 min total exposure) i.e. the dark signal accumulation would be 10 min for the dark and 10min for the light frame (dark signal accumulates regardless of shutter state), but the object signal accumulation is only for 5 min (50% duty cycle on shutter let's say), so the relative size of the dark signal relative to the object signal is twice as big, that's all. This is no problem for bright objects, where you have lots of signal to throw away, but for faint small stuff, not so much.
BTW this is the same strategy as lucky imaging with zero read noise cameras... throw away all the bad frames and stack only the good ones, but if your duty cycle is low because your seeing criteria is tight then it takes too long to record the faint details.
EB
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No - I am thinking that the software would be smart enough that it
would give you say a 10 minute subframe even if the shutter was closed for say 3 minutes.
In that case the dark information would be 13 minutes long & the light subframe 10 minutes.
The light frames would therefore not match perfectly to the dark exposure
meaning that a 10 minute dark frame that you later took to cancel out the 13 minute frame would not match.
That's the problem.