Additionally, you should also expect some loss of AF reliability when using this TC. It's not colossal, but it's definitely noticeable. Usually an f/2.8 lens + TC-20eIII is somewhat less likely to lock onto a target than a longer f/5.6 lens, under the same conditions. Why this is the case, I don't know, but it's definitely the case even on top-spec AF systems like CAM3500 - I presume that the D5100's CAM1000 is at least as affected if not more.
It's still a viable combination, but without such a warning, one often wonders if something is wrong.
_____ Brian... a bicoastal Nikonian and Team Member
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