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11-13-2008, 05:06 PM   #1
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Focus shifting with aperture setting?

Anyone else notice the focus changing with aperture setting on their wide aperture lenses? I wonder if this is the cause of some of the focusing issues.

There's more info at diglloyd: A Brief Introduction to Focus Shift and Spherical aberration

You can see how the focal plane moves in the following image from a Pentax-A 50mm f/1.2

11-13-2008, 05:42 PM   #2
Lowell Goudge's Avatar

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I think what you are seeing is softness of the lens wide open, not a shift in focus.

I sharpened the image in PSPX2 and looked closely, I think the sharpest line is right where it should be

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