Hi again,

A quick question. I've been re-evaluating my preprocessing steps and during that I was taking new bias frames and ran in to an annoying feature of the cr2 raw file.
When using the native format for capturing bias frames the pixel count is 3888x2592 (as per the specification of the camera). But when capturing as a fits file via kstars/ekos the pixel dimensions are 3906x2602. Not such a big deal for building the master bias calibration frame, but when the master frame is used for calibration the frame sizes are different and that leads to improper calibration (if the used sw allows to use different size frames).

So I'm capturing all my bias frames via kstars to get the frame size for all frames. Now that leads me to the question or wish depending on the current possibilities. Currently the lowest exposure limit is 1/100s. I tried setting it to 1/1000s but it wouldn't accept the value. Anyway the camera is capable of taking 1/4000s exposures, which would be ideal for taking the bias frames.

Is there any way of setting the exposure setting lower than 1/100s? If not would it be possible to get an option for ekos to use the camera setting and just trigger the acquisition?

Thank you for pointing this out. As I read your post it became clear to me why my latest processing with bias produced some strange borders. I was not aware of this size difference while creating the bias.
Another way could be to convert the bias frames through dcraw.

Question: Do you create new bias for every new session? My understanding was it would be suffucient to create a masterbias with the lowest possible ISO and the shortest possible exposure.

I don't know how the conversion through dcraw would work, because still you would need to have the cr2 file before conversion. It seems that when the camera saves the cr2 file it already crops the image a little bit. Resizing the image while converting would mean that some extrapolation would take place, which is not good during preprocessing.

My understanding is that the current "best practice" for DSLRs is to make only one master bias at the lowest ISO and use that only on the flats. A new master bias should be made every once in a while. So you don't need to take bias frames for each session.

I changed minimum to 0.001 seconds for GPhoto driver.