Auto-darks

[LewisM]

Do MaxIM created and auto-subtracted auto-darks work as well as regular darks?? They are the same exposure as the sub, then applied at readout to dark-correct the images.

Would adding "real" darks during calibraation later hurt the image in any way, or do they literally mutually exclude each other? I usually let PI run the batch preprocess, so not entirely sure what it does in the script! If I process in CCDStack, I use the calibration setups as usual - doesn't SEEM to affect the data negatively.

Also, any point to using auto-darks during flat frame capture, or is that counter-productive?

[RickS]

Hi Lewis,

A single auto-subtracted dark won't work as well as a master integrated from multiple darks. It will add a lot more noise.

If you dark calibrate twice then you will damage the data. That's the short of shenanigan that could cause the error you mentioned the other day (BPP complaining about no data in some of the subs.)

For flat frames I think you are generally better off just bias calibrating them unless you have a camera with a very high dark current or are doing very long darks. If you do want to dark calibrate them then, again, it is better to use a master integrated from multiple dark frames than a single auto dark though the noise won't have as big an impact because flats have lots of signal.

Cheers,
Rick.

[LewisM]

Thanks Rick. Makes sense.

I wish PI would make an add-on or stand-alone for camera control/capture...

[Bart]

Actually, they do Lewis! ;)

[LewisM]

Well there ya go!

That's one thing about PI - stuff crammed everywhere in non-logical folders etc you don't find them.