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EXCERPT page containing first few paragraphs. 2021-12-04 15:30:21

Field Illumination: Canon 85/1.2L II, 85/1.8, Nikon 85/1.4G

See the test scene and notes on the previous page.

Both Canon lenses show a peculiar variation in illumination as they are stopped down, the 85/1.2L II more-so. This was observed in the other comparisons as well. The Nikon 85/1.4G does not exhibit this effect.

For the Canon images, variations in brightness across the aperture series for exposures that should be perfectly matched are observed here (e.g., 1/5000 @ f/1.2 vs 1/4000 @ f/1.4 vs 1/1000 @ f/2.8). It’s unclear if this is a lens behavior (probable), or a 5D Mark II bug when using Live View Mode II exposure.

Some of the brightness variation includes a peculiar shift in relative brightness over the frame with stopping down— a darker center— very noticeable with the Canon 85mm f/1.2L II, and something I have observed before with both Nikon and Canon lenses. Results show exposures that are mathematically equivalent in all cases, yet significantly variable in brightness.

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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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