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The confusion here is caused by the way so many people incorrectly describe what the "shift" function actually does. Shifting the lens does not alter the scene perspective at all, it simply causes the image sensor to be moved to a different part of the image circle being produced by the lens. For example, the Canon TS-E 24mm f/3.5L Mark II creates an image ...


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Ok, for future people searching for this issue, I think this is resolved. The issue (for me, at least) was not enough light on the target. I was doing the testing indoors, beside a window mid-day (curtains open) and below a tungsten dining room light. But this was not enough light on the target for the auto focus to perform it's best. IIRC, my shutter ...


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In a way you could say that autofocus is less reliable when a lens is zoomed... if you do not correspondingly increase the focus distance. More accurately; what happens is that the depth of focus decreases, which makes any focus errors more apparent (there is always an error tolerance; there has to be). Also, many zoom lenses have more optical errors at ...


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If you are only testing for relative sharpness and focus accuracy then you don't really need a chart at all. You only need a target/subject of good contrast with fine enough details to judge sharp/unsharp. And something with consistent/repeating details that transitions near-far for judging front/back focus (i.e. a ruler placed at ~45* adjacent to your ...


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