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Will new 600 and 800mm lenses autofocus on R/RP?

Started Jul 9, 2020 | Discussions thread
John Sheehy Forum Pro • Posts: 26,688
Re: Will new 600 and 800mm lenses autofocus on R/RP?

BirdShooter7 wrote:

I’d be shocked if they didn’t AF on the R and RP.

Did I hear in the video that they have a fixed f/11 aperture? Like you can’t change the aperture??

That would be odd, because there should be nothing about a lens designed to be used wide open that would start to perform worse stopped down, other than the expected effects of a smaller aperture.

The only exception that I could think of would be if the lens design was such that the the outer light bundles had less aberration than the central bundles, but I don't know if there are many designs like that. That would be true, of course, if you had a chip dead center in the front element; the more you stopped down, the higher the percentage of recorded light there will be that passes through the chip and went off-course.

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