|
Sounds like you're dealing with a DSLR so I agree with Leon that you would be best using dark frames from close to the time the light frames were taken, due to temperature variation of the camera. As such your possibility library size of useful frames is quite limited.
If you were working with a temperature regulated camera then you can more effectively build up an extensive library of dark frames to use over many months or years. Even then I find the darks change slightly over time and so I prefer to take new ones each year or so and stop at a reasonable number like 30 dark frames for a given set of camera settings.
|