D800 Camera Gain for SubframeSelector script

[gsedun]

Hi All - I am working through my first image with PI and the Subframe Selector Script requires a Camera Gain for my Nikon D800.  I've searched the forum and can't find anything.  Any clues on how to determine this?  I am shooting at ISO 3200.

Thanks,

Garry

[mschuster]

Garry, I suggest leaving Camera gain set to 1 and Data unit set to Data Numbers. Table values Median, MeanDeviation, and Noise will then be displayed in DN units, which should work very well. The alternative, specifying a gain and selecting e- units, is just for convenience and is not necessary IMO.

Best,
Mike

PS: If you do need gain for this or some other purpose, the FlatSNREstimator script can give a good estimate. You need two good flats and one good bias frame, all exposed at the same ISO, and all in undebayered raw CFA gray-scale format. Use the SplitCFA process to split these three frames into the four CFA channels each. Choose one of the G channels from each of the three (same channel in each) and run the script. The script will give a gain estimate that should be reasonably valid for all four channels. See the script documentation section 3.2 for an example. The script should give good results as long as your flats are well exposed.

[gsedun]

Thanks Mike - wow, this PI community is quite amazing! 

Could I please ask a few more questions?  Do I need to convert my NEF files to FITS/XISF files right at the beginning of this whole process?  Do I need to separate the Lights/Flats/Darks/Biases, etc. into the RGB components before processing them in the usual manner with the Darks/Flats, etc?  Is there a thread that addresses this?

Thanks,

Garry

[mschuster]

Garry,

I think the standard DLSR process is calibrate pure CFA raw, then deBayer calibrated lights, then register, then integrate. I think the BatchPreprocessing script does all this when you check the CFA Images option (see tool-tip, need to set deBayer options also), using NEF files as input.

By default if you open a NEF file I think you will see an RGB image, with deBayer done by default. To avoid deBayer and open as pure raw, do this: Format Explorer > DLSR_RAW > Edit Preferences > Pure Raw, OK.

There are threads and tutorials on this but I don't know which are the best to check out.

Thanks,
Mike

[gsedun]

Thanks Mike - I appreciate the advice.  I've decided to use PI for my work instead of PS.  I am very impressed with the community and the program.

Garry