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The Power of Calibration, Integration, and Post-Processing

Rosette Nebula

What you see is not what you get

When astronomical data is pre and post-processed correctly, the data, color, structure, and beauty is there!

I wanted to demonstrate graphically how important and powerful the process of acquisition, calibration, integration (also known as reduction or stacking, “pre-processing”), and post-processing (image enhancement) is for astronomical images.

I don’t want people new to astrophotography to be discouraged by what they see on the camera from a single exposure, as it can be VERY disappointing at times. After a few years of experience, I still often get disappointed by the looks of a single image after it comes in, so I still have to remind myself what processing can do. When astronomical data is pre and post-processed correctly, the data, color, structure, and beauty is there!

Single exposure vs. integration (stacking) vs. post-processing
Single exposure vs. calibration and integration (stacking) vs. post-processing

The first image above is a single 6-minute RAW exposure from a Baader IR-modded Canon 550D DSLR attached to a Vixen ED80sf (f/7.5) telescope. Not a single change was made, except conversion to JPEG.

The second image is an integrated (stacked) and histogram-stretched version of the same target. 33 RAW DSLR exposures, all calibrated with loads of dark, flat, and bias frames.

The third image is the fully post-processed image after extensive work in PixInsight.

See the final Rosette nebula below. Nothing magical has been done, just a lot of work and patience.

If you do it right, it works!

Rosette nebula, final post-processed image
Rosette nebula, final post-processed image

Final image details

Exposure and calibration
33x6min ISO800 sub exposures, 3.3 hours total integration time
21 dark, 35 flat, 107 bias

Vixen ED80sf 80mm APO refractor
Celestron CG-5 ASGT mount
Orion SSAG autoguider + 50mm guide scope
Canon T2i 550D DSLR (Baader IR modded)
Orion Field Flattener

Image acquisition with BackyardEOS
Guiding with PHD
Pre-processing: calibration, alignment, and integration (stacking) with PixInsight
Post-processing with PixInsight


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About the author

Cory Schmitz

Co-founder of PhotographingSpace.com, co-owner of several telescopes and mounts, too many cameras, and not enough hard drives, Cory is an American expat living in South Africa with his wife, Tanja Schmitz.

An avid astrophotographer for timelapse, deep-space imaging, lunar, planetary, and star trail imagery, he is an all-around jack-of-most-trades for night-sky photography.

He is also an internationally published and commissioned astrophotographer, where his photos have been used in multiple online and print publications.


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