Focal Pointe Observatory
Astrophotography by Bob Franke

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RGB vs LLRGB Color Test

The left image is a straight RGB combine
RGB 450 min (10 x 15 min each, bin 2x2)

The right image is an LLRGB combine
Lum 510 min (34 x 15 min, bin 1x1)
RGB 450 min (10 x 15 min each, bin 2x2)

Taken w/ an SBIG STL-11000 camera, using AstroDon Gen II Filters.

The speculation is that because the STL-11000 camera's quantum efficiency is highest in the blue, an image with excessive luminance data will be too blue. For this test, note that the luminance data is used twice in the right image.

The R:G:B ratios were 1.00:0.88:1.18. This was determined by eXcalibrator, with only six stars from the NOMAD1 database. The NOMAD data sometimes produces a too-blue color balance.  The color balance is probably about right, as the star colors look correct. 

However, color balance is not in question for this test. We are looking for a difference between RGB and LLRGB... they both look about the same.








STL-11000M QE Curve