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EXCERPT page containing first few paragraphs. 2019-09-23 13:42:58
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Olympus OM-D E-M1

Raw Conversion Silent Auto Corrections with ACR

Adobe Camera Raw (ACR) version 8.3 (141) maintains an undesirable behavior found in previous versions of ACR: it silently corrects for distortion and chromatic aberration with some cameras (and likely for other things too). Perhaps it is responding to some EXIF flag specified by a manufacturer stating “always correct this lens”?

Such auto corrections are inappropriate to the raw format, and have been mostly confined to consumer-grade cameras. Moreover correcting for lateral chromatic aberration can add chromatic aberration if the lens deviates from the expected (by being slightly off, for example)!

This example shows the behavior, including the loss of field of view with the auto correction of distortion. The image also appears rather soft at the edges (everywhere), and this almost certainly has some contribution from pixel-resampling and stretching to un-distort.

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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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Variants ACR, iridient, iridient_corrected available in full article

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