Wow.. I've really confused myself with flats

[LX200]

I thought I had this figured out...

1. I integrated my bias frames to make a master bias
2. I integrated my darks to make darks for different exposure times, I did NOT subtract bias
3. I integrated my flats to make a master flat, I did NOT subtract bias or dark

I then used image calibration to calibrate my LIGHTS...

I pick the master bias
I pick the dark corresponding to my exposure time for the lights... I pick "Calibrate" (this subtracts bias from dark, right?)
I pick the Flat for the correct filter in use, I pick "Calibrate"  (This subtracts scaled bias subtracted dark and bias from flat, right?)

SO... this process will subtract the bias from the darks, and the bias and bias subtracted dark from the flats, right???

This seems like the way to go, since I don't have to subtract bias from darks, and bias/darks from flats, right?  I save time, and Image Calibration does it for me, right?

So I have this right?  Reading some online sources and the new PixInsight book now has me thinking I am messed up doing this, and I should have calibrated Flats, by removing Bias and Dark.... but why bother if just checking a  box in Image Integration will do that for me.

I have a headache.

[pfile]

i always calibrate my flat subs separately, generally only using a master bias frame. this is because usually flats are kinda short and my lights can be up to 1800s, so i'm using an 1800s dark. almost certainly if i tried to calibrate the flats with that dark, i'd get the "no correlation" warning.

flats can be really tricky - if they are not calibrated properly they can end up over-correcting the lights. so i've always felt it was "safer" to calibrate the flats separately, either with a master bias frame, or with a master dark frame that exactly matches the flat duration.

rob

[LX200]

OK... so basically you are saying this will work...

1. Make master bias by integrating bias frames
2. Make a dark by integrating the darks with the proper exposure time (Not subtracting BIAS or DARK)
3. Make a flat by integrating Flats (Not subtracting BIAS or DARK)
4. Do Image calibration using the above, AND check "Calibrate" under the dark and flat

But... you are saying this is a bad choice, as the dark that will be subtracted from the flats may be a vastly longer exposure than the flats, and will be scaled, but this scaling is likely a sucky way to do it.

Also, you only subtract bias, because your FLAT exposures are so short (I have a cooled QSI camera, and my FLATS are sub one second, except for HA, OIII and SII with are like 2 sec)

So maybe I should do that too.... then, when I run Image Calibrate, I pick the FLAT (with the bias subtracted) and do NOT NOT pick calibrate under "Flat"

[pfile]

what i do is make a master bias, then calibrate the flat subs, then make a master flat from the calibrated flat subs. then i don't tick "calibrate" for the flats in IC when calibrating lights.

for darks, it depends on the camera. if i am using my 8300M then i make a master bias, calibrate my dark subs with the master bias, and make a calibrated master dark. then in IC for light, i don't tick "calibrate" for the darks, but i do tick "optimize". of course i have to load the master bias into IC as well since there's no bias signal in the calibrated master dark.

rob