Bias Frames or Flat Darks or Both?

Matthew Humphrey

I am probably over-thinking the information on calibration frames....

I am using an ASI2600MC color camera.  When I take my calibration frames, I use a light panel for the Flats, and the exposure time is very short - typically 1/2 second or less.  From what I understand, there is probably no or negligible dark current in these frames, but you also recommend using Flat Darks in the beginning to be sure and to understand the sensor.

For my situation (or any situation I guess), does it make sense to use both Bias and Flat Darks?  Since the exposure time is so short, it would only take a minute or two to take the additional frames.  But is there any harm or benefit to using 5 different types of frames given the short exposure times?

Lights

Darks

Flats

Bias

Flat Darks?

BlockHead

Here is the deal, unless you have an amp glow or some other kind of electronic signature that is an issue- just take Bias frames and use them to calibrate all of your flat field images (which might be of varying times). This is the normal way. The reason I cannot suggest this...is that not everyone has nice sensors... there is no harm in matching darks for flats calibration. But it may be unnecessary. There is no benefit to having both. WBPP will pick the matched darks if they exist and ignore the biases. 

There is *another* reason to have bias frames that WOULD require having darks too. This is in the case of dark frame scaling/optimization. But this isn't something you should be worrying about in general.

-the Blockhead