Canon has added the RF 800mm F5.6 and RF 1200mm F8 to their mirrorless EOS R series cameras using the RF mount. This is presumably due to Canon experiencing a little pressure from Sony, as they’ve recently started targeting sports and action photographers with high speed telephotos to go with the Sony A9 and A1 cameras.
Even Nikon have announced an interesting alternative with their PF 800mm F6.3, which appears to be targeting birders but no doubt, due to the smaller sizer and lower weight, but will also appeal to sports photographers.
It’s a prudent move from Canon, however these two new lenses aren’t quite what they appear to be. From the optical construction diagrams it seems, if we’re to believe they’re accurate, that Canon has simply added a super-high quality ‘extender’ behind the current RF 400mm F2.8 and RF 600mm F4.
If you look at the above cross-section (above) immediately in front of the optical blank at the rear of the lens (which is a part of the optical formula) of the RF 400mm F2.8, and then compare it to the RF 800mm F5.6 (below), you see the configuration is identical save for the last nine elements behind the last group. It appears to use a UD element in the first group and then there’s seven smaller elements, which is what I’m call a high-quality extender. It’s exactly the same with the RF 1200mm F8 when compared with the 600mm F4, so I’ve not included it here.
Disregard the group of three element highlighted in the red-box, which is the IS component.
Why would Canon do this? Well, there are several reasons, all of which are pure conjecture on my part. Their R&D department would have designs for high-quality extenders like this but such an extender would likely sell for between £/$3 to 4K, maybe more and would be a hard sell for an ‘off the shelf’ extender. I would also point out that lenses like this are made in small batches and the ‘extender’ will be specifically matched to the lens. It’s not possible to do that with ‘off the shelf’ extenders, which aren’t even matched for a specific focal length, let alone an individual lens.
This design should result in very high image quality while also delivering size and weight reductions (the lenses weigh 3.1 and 3.8Kg respectively) and short MFDs and so shouldn’t be seen as a short-cut. I should point out the design also allows for the RF 1.4x and 2x extenders to be added with the usual caveats.
Adopting a super-extender like this means there are gains for Canon in streamlining the manufacturing process. Given sales are likely to be small, when making the RF 400mm F2.8, for example, it’s going relatively simple to double up with a few 800mm F5.6 models using the extender. The same applies for the 600/1200mm combination.
This makes a lot of sense in the short term to combat aggressive moves from Sony and to a lesser extent Nikon, the latter seemingly now conceding some ground in the pro-market and concentrating on ‘well-heeled’ enthusiasts.
I for one am extremely excited by lenses like this, and hopefully I’ll be able to review them here on this site in time.
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