Adding Darks of different Gains in WBPP

N

njeevanjee

Member
I have two master dakrs of same exposure but different gains. ( 0 for LRGB and 300 for Ha). Even if I include both the master darks WBPP picks up only one of the master dark for calibration of the light frames. I want to apply dark of 300 gain for Ha lights and master dark of 0 gain for LRGB lights.
 
Yes, the video below explains the concept. Since "Gain" is found in your header- you can simply add "GAIN" as a pre-processing keyword and everything should work exactly as you want. Thanks @robyx .

 
Adam, others, I've just tried this in WBPP and it doesn't work for me but I may have a little different situation.
My lights, and darks all use Gain 100. But my flats and dark flats are mixed in that my broadband flats use gain 0 to have reasonable exposure times, but my narrowband filters use gain 100, otherwise with my light panel exposures would be very long with Chroma 3nm filters. When I apply a grouping keyword of gain and try to add a flat, created with gain 0, which has a corresponding gain 0 dark flat it will not allow me to apply this flat to a light image which has gain 100. In fact it gives me a circle with a line through it if I uncheck auto and try to assign it manually.
If I turn off grouping keywords I can again assign my broadband flats to corresponding lights, but the program does not separate out the gain 100 and gain zero dark-flats and I can't calibrate my Ha flat and Red flat properly (my Ha flat and Red flat both use 1.45S but one is gain 0 and one gain 100 so the program combines them into one 1.45s image.

I am shooting LRGB Ha for this sequence.

I think it is a valid calibration (correct me if I'm wrong) to use gain 100 for all lights, and all darks (consistent) but for my flats, use gain zero for broadband and gain 100 for narrowband with corresponding gain for dark-flats to calibrate the flats. But it seems WBPP will not allow this.

It would be nice to manually be able to assign the dark-flats to the calibration of flats. Today it's only automatic.

Comments?

Terri
 
Theresamarie1 said:
Adam, others, I've just tried this in WBPP and it doesn't work for me but I may have a little different situation.
My lights, and darks all use Gain 100. But my flats and dark flats are mixed in that my broadband flats use gain 0 to have reasonable exposure times, but my narrowband filters use gain 100, otherwise with my light panel exposures would be very long with Chroma 3nm filters. When I apply a grouping keyword of gain and try to add a flat, created with gain 0, which has a corresponding gain 0 dark flat it will not allow me to apply this flat to a light image which has gain 100. In fact it gives me a circle with a line through it if I uncheck auto and try to assign it manually.
If I turn off grouping keywords I can again assign my broadband flats to corresponding lights, but the program does not separate out the gain 100 and gain zero dark-flats and I can't calibrate my Ha flat and Red flat properly (my Ha flat and Red flat both use 1.45S but one is gain 0 and one gain 100 so the program combines them into one 1.45s image.

I am shooting LRGB Ha for this sequence.

I think it is a valid calibration (correct me if I'm wrong) to use gain 100 for all lights, and all darks (consistent) but for my flats, use gain zero for broadband and gain 100 for narrowband with corresponding gain for dark-flats to calibrate the flats. But it seems WBPP will not allow this.

It would be nice to manually be able to assign the dark-flats to the calibration of flats. Today it's only automatic.

Comments?

Terri
Click to expand...
Unless your camera has some very strange non-linearities (which is unlikely), there is no reason to match the gain and offset of flats to the gain and offset used for lights and darks. You do, of course, need to match those settings between your flats and the darks or biases you use to calibrate the flats.

I don't think that WBPP has any knowledge of either gain or offset, so those values do not contribute to how it groups images. It uses image type, filter, binning, and exposure time. Those are the only things you have to keep track of, either by using the grouping keyword feature, or by loading the files manually with the "Add Custom" button.
 
Thanks guys for clarification that my calibration is valid. I've got everything to work except for a situation where i have the same exposure time and 2 different gains, one for broadband and one for narrowband (flats calibration). I'll see if I can define a keyword for the two file type and put them in special directories with a keyword (red and ha) that keep them separated.
 
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