Teardown: Canon EF 400mm f/2.8L IS III

Canon Rumors Guy

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Lensrentals.com has done something I’ve never seen before, and that’s tearing down a working Canon super telephoto lens. In this case, it’s the brand new EF 400mm f/2.8L IS III, the world’s lightest 400mm f/2.8 lens.
An interesting bit of information that Roger and Aaron did get from the teardown, is that the EF 400mm f/2.8L IS III uses the same focusing motor as the RF 50mm f/1.2L.
This is a great teardown and not for the faint of gear heart.
From Lensrentals.com:
Some things we were already aware of or assuming. The lens elements are moved towards the mount side of the lens. There are lots of optical adjustments like all Canon lenses. Despite being far lighter, it’s still very solidly built with a very strong frame, tons of big screws holding everything together, and no weak joints that we can see. It’s what we expected; Canon’s been building super telephotos for a long...

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YuengLinger

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Not really. One just has to go back to the Auguat 2016 thread (CR3) and read the "lipstick on a pig" comments and "EF's last gasp" and etc. ;)
If EF is depending on sales of $12,000 USD Big Whites modified to work better with RF, then EF is up in some pretty thin air.
 
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I just wonder that Canon builds those lenses in dust-controlled environments with technicians wearing gloves, masks and other protective apparel.... LensRentals chooses a very different approach... or do they change it when reassembling them?

And yet, they all have dust in them when we get them. :) Every lens does, it's just whether you have a strong enough light to see it. Also we aren't working in a large factory with machines milling things, etc. While not a clean room, we have pretty good dust scrubbers where we work.

But yes, to some degree we change tactics during reassembly. We can be cavalier during disassembly: the pieces are all going to sit on a table for a while so they will all have dust on them when reassembly starts. The main reason that reassembly takes longer is every piece is cleaned as it's reinserted. It's not unusual, too, for Aaron to do a bit of disassembly during reassembly because he finds he missed a piece of dust or a smear on an element.

As a TMI aside, this is part of the reason I can no longer do the disassemblies myself. As I've gotten old my close vision isn't good enough to find the small bits of dust that Aaron sees easily. Bifocal jokes may start now.

Roger
 
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I was kind of hoping Roger would find some evidence that these lenses could be factory "upgraded" to RF mount/electronics in the future. Sounds like the internal components share a lot of RF design but they will always require EF to RF adapters. I guess they'll be a separate RF version at some point.
When they do RF-mount superteles, they will be completely different lenses (possibly DO lenses to cut down weight - increase price - even further, different interface, control ring, different aperture mechanism, etc.) but that's another 7 years when it might become somewhat feasible for the agencies to switch cameras and lenses. But in the meantime they might also launch more compact ones that are more similar to what they had considered for the EF-mount in the past.
 
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Del Paso

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I like these teardown articles but I have to wonder, doesn't Canon have a "factory trained repair tech" program? The LR people always seem to be having to guess how things come apart when it seems like they should be able to go learn how to do it from Canon.
What if Canon prefers to do the repairs themselves ($$$$$) ?
Lens Rental is , obviously, a rental, not an official repair facility. They must be busy enough with their own stuff, without being asked to repair customer's warranty damages.
 
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