When to Subtract Bias from Dark Frames

[MikeWiles]

Hi all,

Just looking for some clarification on the preferred process when creating master calibration frames.  I've used Vincent Peris' excellent tutorial to learn what little I know at this point.  I'm going through and truly studying it to gain a better understanding of the role of each calibration frame.  In regard to my specific question - it's a little unclear.

So my question - when is it best to subtract the bias from dark frames?  Should I create a master bias frame and then bias subtract each individual dark frame prior to integrating them into a master dark frame?  If I do it this way....then I presume that during the actual Image Calibration of a typical light frame that I would not want to check "Calibrate" under the Master Dark section, is that correct?

Or is it better to just do the integration of the master dark frame without bias subtracting each individual frame and then turn on the "Calibrate" checkbox during Image Calibration on the light frames and subtract it just once?  My sense is that it should be subtracted from each individual frame....but I wanted to ask here and further my understanding of the actual process.

Thanks in advance,

Mike

[Cleon_Wells]

Mike, I've had problems integrating calibrated Dark subs to create my MasterDark. Check this post out.
http://pixinsight.com/forum/index.php?topic=3663.msg25252#msg25252
Cleon

[Geoff]

The easiest way to calibrate is to use the batch preprocessing script.  Harry has a good video here http://www.harrysastroshed.com/preprocessing.html
Geoff

[Alejandro Tombolini]

Hola Mike.

I use master dark integrated without subtraction of bias and then use "Calibrate" during ImageCalibration to subtract masterbias.

Saludos. Alejandro.

[Ignacio]

I prefer to do the bias calibration after building a master dark, to avoid negative numbers (clipping) when the dark signal is low (short subs and/or cooled cameras).

I understand that that is the way the  batch pre-processing script does it, right?

Ignacio