PixInsight Forum (historical)

PixInsight => General => Topic started by: Armando on 2018 June 14 08:09:49

Title: Flat - DARK and BIAS calibrated - Is it worth it?
Post by: Armando on 2018 June 14 08:09:49

Hi,
do you think it's worth calibrating flat frames by Master BIAS and Master Dark (BIAS subtracted and then optimized)?

I'm going to take flat frames with 1.3s exposure time by a temperature controlled KAF 8300 CCD. I still don't know if Pixinsight will find a correlation between the flats_masterBiasSubtracted and masterDark_masterBiasSubtracted...
What I know is that I noticed no correlation was often reported when using a DSLR when calibrating the flat frames so that, to calibrate flat frames taken by DSLR, I'm used to opt only for bias calibration.

Thanks
Armando

Title: Re: Flat - DARK and BIAS calibrated - Is it worth it?
Post by: RickS on 2018 June 14 13:51:09

For short flats I only use bias for calibration but I run the sensor pretty cold.  How well this works will depend on the characteristics of your camera.

Title: Re: Flat - DARK and BIAS calibrated - Is it worth it?
Post by: chris.bailey on 2018 June 14 14:46:06

Flats on the KAF8300 need to be several seconds long to avoid the shutter causing shadowing.

For short duration RGB flats I tend to only Bias subtract my flats but for longer duration narrowband i take a series of say 30 second darks and then Bias/Dark/Optimise.

Chris