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Samir Kharusi | all galleries >> Galleries >> Dark Sites and Filters > N American from Suburb of Montreal
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2-3 July 2006 Samir Kharusi

N American from Suburb of Montreal

Beaconsfield, Quebec, Canada

Since this is an H-alpha image, there is information content only in the Red channel. I processed the stacked and calibrated Red channel and then colorised the stars by using a stack of frames shot with no filter at all. Because of the very high light pollution the starfield was shot using 2-minute frames at f11, since I wanted to use the same darks. That's why there are diffraction spikes on the brightest stars. The background was set to a dark greenish blue. These deep red images are often disappointing when printed. The reds do not go as bright on printed paper as they do on a monitor, with a consequent loss of contrast in the brightest red regions. Consequently I found it useful to add a bit of white to the brightest red regions, leading to prints with more prominent structuration. While the star colours are retained, it may be difficult to perceive their subtle variations because of so much red all around, but easier on a large print. Basically, I had to pay much more attention when chasing good prints than for web use. For web use white stars seem to be good enough and no white-brightening needs to be added to aid the presentation of structuration in the brightest red regions. Click "original" below to see what I am talking about.

Hutech 20D+Astronomik H-alpha Filter,Canon 200mm/2.8 II
43x2min exposures calibrated with darks, flats and bias. ISO 1600, lens wide open but the 2" filter stops it down effectively to about f4.5 full exif

other sizes: small medium large original auto
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