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DSLR. Help! What am I doing wrong
While my asi071 is being upgraded I've gone back to using my dslr (550D modded). I'm using APT to collect the data - ISO400 120sec subs - and saving as raw CR2 files. I've used APT with the 071 before but not my dslr.
When I looks at the FITS files (in fitswork) my dark and bias frames have negative values - down to -300 ADUs. The lights all have positive values range from ~300 up to 63,100. I didn't think I could get negative values?
I've put it into PI and everything comes out between 0-1 (good). But when I calibrate the lights and start to process they all end up being clipped at the black end (bad). The shots look OK, but as of the clipping I can't stretch and reduce the background.
What the heck am I doing wrong???? Have I got some sort of offset problem?
Hope this description makes sense.
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