Gordon Laing from CameraLabs gives his first reviews of the new Canon gear, including the EOS R3

neuroanatomist said:

There are only a very limited set of lenses that have reduced functionality with the adapter, and they're mainly really old lenses. The early 90's EF 35-80mm PZ lens doesn't power zoom when adapted to an R-series body, and the AF Stop buttons on the MkI IS 'great whites' (200/2, 300/.8, 400/2.8, 500/4, 600/4, 800/5.6 and 400/4 DO) don't work via the adapter (source).

However, there are some notable body limitations with EF lenses. There are several 'popular' lenses, albeit older ones, that don't support 12 fps on the R5, e.g. the 100-400 MkI, the 85/1.2L II, etc. Those lenses could do 16 fps on the 1D X III, but are limited on the R5. As another example, the R5 and R6 (and presumably the R3 will) offer focus bracketing – that works with all the RF lenses but only with four EF lenses and three EF-S lenses (most of the macro lenses are on the list, but not the 100mm non-L and not other lenses with reasonable magnifications, like the 100-400 II

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neuroanatomist said:

However, there are some notable body limitations with EF lenses.

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Pixel said:

If you think all of your old EF lenses are going to work perfectly on the R3 you're delusional because it's physically impossible due to the lack of electrical contacts compared to the RF's.

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neuroanatomist said:

If you read my post and think I said all my EF lenses are going to work perfectly on the R3, you’re the delusional one here.

Incidentally, your post is not illogical. The R3 has more contacts than an EF lens, therefore there’s no reason why all the functionality provided by a DSLR to an EF lens cannot be provided by an R-series body. Obviously only an RF lens can make use of the extra R body contacts for additional functionality.

EF lenses should work as they’re designed on an R body, and for the most part that’s exactly what happens. Except for the lens functionality changes I listed, the limitations are on the body side – the R bodies cannot deliver full functionality with an adapted EF lens. The R5 cannot automatically focus bracket with the 100-400 II, but the 100-400 II cannot automatically focus bracket on any body. The lens limits the functionality of the body.

No one should expect them to work the same as an RF lens on an R body.

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Pixel said:

I misspoke, the EF lenses will work perfectly, the camera however will be greatly throttled in performance.

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neuroanatomist said:

Greatly? Not sure about that.

The majority of the recent high end EF lenses can do 12 FPS mechanical shutter on the R5, so presumably they can do so on the R3. They can also shoot 20 fps electronic shutter (i.e., they are on Canon’s “List of lenses that the continuous shooting speed of max. approx. 20 fps less likely to decrease,” a list that also includes several RF L-series lenses (link). Not a lot of throttling going on there, beyond general caveats like a too-slow shutter speed limiting fps, which apply to all lenses.

I’m fairly certain that life without automatic focus bracketing is possible, at least for most people.

Perhaps you could provide some details about how, exactly, EF lenses are ‘greatly throttled in performance’, preferably with some references or documentation?

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SteveC said:

If he was thinking of the R3 (which would be germane to this thread), 20 fps is less than 30 fps so some of those lenses might slow the R3 down, depending on what their actual maximum capacity is. (If it's 20 fps, then yes, a 33% hit, if it's 35 fps, then no problemo.) All Canon said is they could keep up with an R5 at 20 fps.

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neuroanatomist said:

Since we have no idea what the situation will be for the R3, it's a rather premature to claim 'greatly throttled'.

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Pixel said:

My EF 400 2.8 L IS II doesn't get near the FPS in mechanical shutter as my RF 28-70 f2L and the 400 isn't all that old. If you think all of your old EF lenses are going to work perfectly on the R3 you're delusional because it's physically impossible due to the lack of electrical contacts compared to the RF's.

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