Flats and Darks for stacking Livestacks

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zerolatitude
Posts: 156
Joined: Mon Mar 01, 2021 5:24 am

Flats and Darks for stacking Livestacks

#1

Post by zerolatitude »

Hi,

Im trying to stack multiple livestacks - aim being to reduce the number of subs to be stacked by my PC, but facing a problem with calibration frames.

I take the flats as usual, but DSS doesn't accept them, saying the file structure is different from the lights.
Lights (livestack files saved as fits) : RGB 16 bit, CFA No
Flats / darks from SC come as : 16bit Gray, so it is marked as incompatible. If I debayer, it still doesnt work, as now it shows CFA yes while lights are No.

Any suggestions?

Thanks
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admin
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Re: Flats and Darks for stacking Livestacks

#2

Post by admin »

Hi,

you cannot apply calibration frames when stacking live stack output images - well strictly speaking you can... but no good will come of it.

The reasoning is this - during live stacking each incoming frame is aligned with the previous stacked image and added to the stack - this compensates for any drift/rotation in the field of view. But, it means that the saved live stack image is not mapped 1:1 with the pixels on the sensor, so trying to use darks/flats on that image will give incorrect results.

Basically, darks and flats have to be applied in SharpCap so that they are applied to each frame before the alignment and stacking step.

The other option is to save the RAW frames while live stacking, which can be processed in DSS etc in the traditional manner.

cheers,

Robin
zerolatitude
Posts: 156
Joined: Mon Mar 01, 2021 5:24 am

Re: Flats and Darks for stacking Livestacks

#3

Post by zerolatitude »

Very clear.

Thanks
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