Hi Lee,
I thought I killed your thread with my last post...
Yes, I used only a single sub for testing. Your method of applying calibration frames to a set of subs is superior to mine as you basically have a larger number of samples for more accurate statistical analysis. But again, I think that measuring StDev for parts of the image, in particular in the areas of low signal, gives a better indication of noise as opposed to comparing StDev for the entire images.
More darks and more bias is always better, but I feel that after certain point you can successfully apply noise reduction techniques to MasterBias and MasterDarks and get a very similar result as with a significantly larger number of calibration frames taken to create less noisy Master Bias and Dark frames.
It essence, Master calibration frames can/should be approached in the same way as one would work with the "normal subs" (Lights) - you want a sufficient number of subs to have a good signal and then you apply noise reduction without distorting your "real" data (signal), and that data (signal we are after) can be from the sky (Lights) or from the camera (Bias and Darks).
Oh no, I have been waffling again...
