NGC 7023 is a beautiful emission nebula that resembles an Iris flower. The dark areas in this photograph are places where there is cold dust in space. This dust blocks the light from the stars behind it, yielding blank, dark spots in the sky.

In this image, North is Up. This image is cropped to 96% of the original full frame.

Exposure Details
Lens	Celestron C-8 SCT with Celestron focal reducer
Focal Length	1160mm (measured from the image)
Focal Ratio	f/5.8
Mount	Schaefer GEM - 7 1/2 Byers Gear
Guiding	ONAG On-Axis Guider, Lodestar autoguider, PHD Guiding
Camera	Canon 450D - Gary Honis modified
Exposure	306 subexposures of 180 seconds each at ISO 1600 - a little over 15 hours
Calibration	30 darks, 30 flats, 30 bias
Date	August 20, 21, and 22, 2012
Temperature	68F on 8/20, 63F on 8/21, 61F on 8/22
SQM Reading	21.4 (Bortle 4) on 8/20, 21.5 (Bortle 4) on 8/21 and 8/22
Seeing	4 of 5 on all 3 nights
Location	Pine Mountain Club, California
Software Used	Images Plus 4.5 for camera control, calibration, stacking, digital development, multiresolution sharpening, smoothing and noise reduction. Photoshop CS5 used for levels and curves, focus stacking, color correction, high pass filter, star shrinking, saturation adjustments, lab color, match color, vibrance, selective color, smart sharpen, screen mask invert, and HDR toning. Gradient Xterminator for gradient removal. Carboni Tools for additional saturation adjustments, noise reduction, and smoothing. HLVG for additional color correction. Registar for aligning stacks.
Notes	I had photographed this object last year and had a pretty good result. However, I'm much happier with this year's version and the better edges I have from focus stacking as well as the better noise performance of the 450D over the 20Da. This is a very tricky object to process, and I may end up reprocessing it some day, as I don't think I did the best job pulling out some of the very faint out dust regions.