EXCERPT page containing first few paragraphs. 2024-04-16 12:08:23
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Focus Shift, Close Range
Shot with the Canon 5D Mark III at ISO 100, tungsten lighting.
The Canon EF 35mm f/2 IS has somewhat low contrast wide open even in the center, which hints at possible spherical aberration. With spherical aberration responsible for focus shift, it seems prudent to check for its presence, even though an f/2 lens usually has little focus shift.
This test is at close range; behavior is not necessarily the same at greater distances, but it is harder to detect at distance.
Aperture series (crop)
The crop shown here is from the dolls 35mm comparison.
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Diglloyd DAP is DSLR-oriented, but also contains workflow and other topics. Much of the focus is on Canon and Nikon but also Pentax and Pentax medium format.
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