i am using siril for processing my images (following Tutorial preprocessing) and it works great so far, thanks.
I have some questions regarding bias frames though:
- Are bias frames only needed when using dark optimization?
- Should dark optimization be used, if the dark frames and light frames are taken at the same condition (iso, exposure time, temperature)?
- In the tutorial the master bias frame is subtracted from each dark frame, so the master dark does not contain the bias signal. But the formula in the documentation implies that the bias frame is subtracted in the preprocessing step, so if I use a dark frame without the bias signal, the bias signal will be subtracted twice. What is the correct way to do it?
- If I subtract the master bias frame from the dark frames according to the tutorial, the processed master dark has very small values (even negative), since the bias and the dark frames have (in my case) a similar brightness. This was unexpected but could be correct according to https://www.qhyccd.com/bbs/index.php?topic=6159.0
- However in that case the negative values might lead to problems and the cosmetic correction does not work, since there are lots of cold pixels identified.
So basically the question is, should I use bias frames (if the dark frames are taken at the correct conditions) and if so, what is the “correct” way to do it?
I am grateful for any help and insights!