EXCERPT page containing first few paragraphs. 2021-12-05 16:38:06
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This is a rigorous (very demanding) test at infinity focus at 300mm. It explores the symmetry issue seen with other field images.
Atmospheric haze was a factor here through many miles of air; contrast was added via a tonal curve in order to compensate.
White Mountain Research Center
June 20, 2013, 6:40 AM. The lens was on a tripod, and zoomed to 300mm, optical stabilization disabled as it ought to be on a tripod. A remote release was used along with vibration-free Canon Mode II Live View exposure.
Shutter speeds ranged from 1/1250 second at f/2.8 to 1/30 second at f/16. Although care was taken, there is always some risk of movement at lower shutter speeds. Apertures f/4 - f/11 received a 1/10 stop pull compared to f/2.8. Aperture f/16 received 2/10 stop more exposure (was darker than it ought to be), in order to match f/11 in brightness.
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