EXCERPT page containing first few paragraphs. 2019-09-18 12:03:15
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Mitigating A7R Micro Contrast Diffraction Losses with Sharpening
See also Sharpening A7R Raw Files in Adobe Camera Raw and Topaz InFocus.
This discussion uses an image from the 36-megapixel Sony A7R, but the same principle applies to any camera. The finer the pixel pitch (the smaller the pixels) the more diffraction degrades per-pixel image quality*. This stems from the size of the “circle of confusion”, which grows in size as the lens is stopped down, and places a hard limit on resolution.
Speaking in full frame terms and when utilizing high-grade lenses, diffraction effects for a 36 megapixel sensor result in a faint dulling of micro contrast at f/8, a very noticeable but manageable dulling at f/11, and so much dulling at f/16 that f/16 is visibly inferior to the lens wide open (for a high grade lens). Moving to a ~54 megapixel sensor, take off one stop: f/11 is degraded to a similar degree as f/16 as on the 36-megapixel sensor. Again, this is on a per pixel basis.
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Special emphasis is placed on Sony full-frame, including Sony lenses and the high performance Zeiss Batis and Zeiss Loxia lenses plus Rokinon/Samyang and others. Fujifilm X, Olympus and Panasonic M4/3, Sigma dp Merrill and dp/sd Quattro are also covered in depth. Years in the making, it offers a wealth of material for choosing and using a mirrorless camera.
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