Master Flat - Does Dark Exposure Time Matter?
Here is the situation. I am using a DSLR and have several Master Dark files saved at various exposures (ISO 3200 30s, 60s, 90s, 120s, 180s, etc). When I shoot a session I will typically have 2 sets of lights the next morning, say 90s and 120s. I then take my flat frames.
When I pull in the files to make my Master Flat I use my Master Bias and BPM. Do I need to make 2 master flat files - one with the 90s Master Dark and one with the 120s Master Dark, or do I create I master flat? (And if 1 master flat, which master dark is the best to use)?
A flat is just there to correct vignetting and dust, a master bias or dark flat is what is needed, darks are not used for that. If you have all masters created automatically from the various frames, APP will automatically use the correct ones for each process.
Thank you for the explanation Vincent. Very helpful.