EXCERPT page containing first few paragraphs. 2019-02-22 01:29:05
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Field curvature images a planar subject into a non-planar object image— in a sense warping or undulating its focus. A wave-type field curvature is very common with full-frame 50mm lenses, and wide angle lens designs show both forward (closer focus at the edges) and rearward (more distant focus at the edges).
For more on field curvature, see Making Sharp Images.
With a macro lens, the expectations for minimal field curvature (a “flat field”) are much increased especially with a long focal length. For Micro Four Thirds, 60mm is a long focal length (120mm field of view in full-frame terms). Thus, it is a reasonable expectation to have a perfectly flat field with this focal length.
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Diglloyd Guide to Mirrorless offers comprehensive integrated coverage of most APS-C and full frame mirrorless cameras and lenses.
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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