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

Started Jul 9, 2020 | Discussions thread
rrc1967 Senior Member • Posts: 1,984
Re: Yes and no

Jon555 wrote:

quiquae wrote:

John Sheehy wrote:

quiquae wrote:

Jon555 wrote:

They will definitely AF as-is, f/11 is fine for all DPAF, but I doubt you'll be able to add the extenders, especially the 2x, and have AF work (other than with a R5 or R6 that is).

Actually, I think you're wrong about that. Canon's official product pages for the extenders are now up, and they don't say anything about the extenders not working on R or RP.

It's not about the TC itself where there may be an issue; it is about the resulting open f-number. Canon says f/22 works on the R5 and R6, meaning that AF is reasonably fast and reliable by some standard. It is possible that the same f/22 will be more difficult for the R and RP, with more hunting in low light and low contrast.

EOS R actually has exactly the same low-light focusing spec (EV -6 @ F1.2) as R5, and only half a stop behind R6 (EV -6.5), which suggests that it shouldn't lag much the newer bodies in low-aperture focusing, if at all. But we'll see.

The question is will the R and RP focus at f/22, and I've never heard anything vaguely like that mentioned (just f/11, e./g. see the quote below). The issue is the size of the aperture rather than the amount of light you are getting.

"The AF points on the EOS R are compatible with maximum aperture f/11 at all AF positions (when used with a compatible lens and extender, such as the EF100-400mm f/4.5-5.6L IS II USM lens paired with a 2x extender). This makes AF possible even when shooting at a super-telephoto 800mm, dramatically expanding shooting possibilities for wildlife photographers."

F22 probably not. however, F22 is with a tele extender.  F11 probably yes.

I seem to recall F16 being a limit, but to be honest after a while at this over the past week i'm lucky to remember my birthdate.

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