ClarkVision Photography: Astrophoto 1 Gallery

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image m42.300mm.c11.21.2014.0J6A1657.e-c1-1338s.jpg is Copyrighted by Roger N. Clark, www.clarkvision.com

The Great Nebula in the Sword of Orion 1-Minute Exposure

The three stars that make up the sword of Orion are surrounded by beautiful nebulosity that can also be seen in small telescopes. In the center is Messier 42 and M43. Large amateur telescopes will also show the nebula's blue and pink colors in the brighter parts. This is one of the top showpieces in the sky.

Technical. Canon 7D Mark II 20-megapixel digital camera and 300 mm f/2.8 L IS II at f/2.8. A single 60-second exposure at ISO 1600 exposure plus a 10 second exposure for the Trapezium region. The 1-minute raw file was converted to a 16-bit tif and the images was stretched in photoshop to show the range in intensities. The image shown is at 1/2 full resolution. No dark frame subtraction, no flat fields no bias. Tracking with an astrotrac.

The Exposure Factors, CEF, CEFA are measures of the relative amounts of light received from a subject. It can be used to fairly compare wildly different lens/telescope apertures and exposure times. For this image:


Out of camera jpeg showing the light pollution for this image. Learn how to properly subtract light pollution in the astrophotography series here:
2d) Verifying Natural Color in Night Sky Images and Understanding Good Versus Bad Post Processing
3c) Astrophotography Image Processing with Light Pollution

Daylight color balance. This is a stock camera with very close spectral response similar to the human eye. Astrophotographers often modify cameras for increased sensitivity to Hydrogen-alpha emission (red). The pink and light blue colors are the close to what I have seen visually through large telescopes though a little more pastel. Hydrogen emission nebulae actually appear pink due to H-alpha (red), H-beta (blue) and emission from other atoms, like oxygen and sulfur. Modified cameras over emphasize H-alpha, making hydrogen emission nebulae come out red in photos. Unmodified cameras do a better job at color separation of the various processes that occur in the deep sky. Modified cameras tend to show mostly red in areas like that in this image, making it too difficult to tell the difference between dust and hydrogen emission nebulae. For more information on this topic, see: The Color of Nebulae and Interstellar Dust in the Night Sky


To learn how to obtain stunning images like this, please visit my Extensive Articles on Photography .

See my review of the Canon 7D Mark II and why it is so good for astrophotography: Canon 7D Mark II sensor analysis.


Keywords to this image = astrophoto-1 Messier nebula digital_astro canon_7d2

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Last updated September 17, 2018