Calibration issues

[mar504]

I'm sure I'm making some kind of obvious mistake, but I can't seem to calibrate my lights. I used a Canon 6D and a flat box (tracing paper with some LED's behind it), I will admit the batteries were dying on my flat box so the brightness levels varied by quite a bit, but the resulting master flat at least visually looked OK. However when I calibrate them with my lights the end result is a blue image with some purple spots where bright stars/galaxies are, what am I doing wrong???

Here is an image of the lights/flats/calibrated result and my imagecalibration settings.
http://i.imgur.com/zV69jpS.jpg

[pfile]

is the master flat made from calibrated flat subs?

rob

[mar504]

That's correct, a master flat made from 20 flat frames.

I've made some progress, I realized I had not set DSLR_RAW to "Pure RAW" in the process explorer. Now I actually see my image, but the flat seems to overshoot the mark and has made the vignetting and dust motes too light. I used the "equalize fluxes" when I integrated the flats into a master since the light levels varied a good decent amount.

I don't see any options to change the intensity of the flat against the light frames, any ideas?

http://i.imgur.com/c8c6zlS.png

[mar504]

If it's of any help, I've uploaded the master flat and one of the lights here:

http://s196260749.onlinehome.us/images/4-1-2016 Master flat2.xisf
http://s196260749.onlinehome.us/images/m84_300sec_1x1__000048_2016-04-02_amb_-2.6C.CR2

[Carlos Milovic]

Were your flats calibrated with bias frames?

[mar504]

Carlos, yes, I have the flats calibrated with a superbias (50 subs to create the master, then ran the superbias process with the defaults).

Another interesting thing to note is my lights are pretty much all black if I use my superbias or masterbias during ImageCalibration. Just tried to redo my master bias but it gives the same results 

[pfile]

was discussing this with someone today - is the flat ISO the same as the light ISO? meaning if the flat ISO is different then you'll need bias frames at a matching ISO.

rob

[mar504]

Yup, both were taken at 1600 ISO

[pfile]

ok i looked at the xisf of the flat, can you post a single flat CR2? i am wondering if the blue channel is overexposed. that will mess everything up for sure.

rob

[mar504]

http://s196260749.onlinehome.us/images/m84_0.1sec_1x1__frame9.fit

Just realized the flats aren't in CR2... hmmm... I was using Sequence Generator Pro to capture the data, wonder if I screwed something up here.

[pfile]

i think that's normal for SGP - it converts to fits.

rob

[pfile]

were the bias frames also captured with SGP? how about the lights?

SGP must be scaling the data in the flats... almost all canon cameras have 14-bit D/A converters, so in a straight conversion to 16-bit integer, you should never see values > 0.25. however, in this flat (and in another SGP user's canon flat) i see values up beyond 0.35.

i guess i need to load a CR2 into SGP and save it out as fits and see what it does.

rob

[pfile]

yeah, this is kind of bad. SGP is rescaling the 14-bit data to 16-bits. this probably means that if your bias frames are CR2 files from canon's software or backyardEOS, the calibration of the flat is going to be all wrong. if the bias frames were captured with SGP then i suppose it should work.

another thing you could try is to take all the .fits files from SGP and multiply them by 0.25 (using Pixelmath and ImageContainer), which should return them to compatibility with CR2 files opened by pixinsight.

rob