Teardown: Canon RF 70-200mm f/2.8L IS USM

Cochese

EOS 80D
Oct 22, 2014
132
66
I love this diagram and explanation, but Sony has stated repeatedly that the mount diameter doesn't limit their lens design. I think they also claimed that the E mount could theoretically take f/0.95 lenses, but that they didn't have any planned. Would an f/0.95 lens also feature huge elements at the front of the lens and smaller ones at the rear, thus changing/throwing off the balance on the body? According to what you've posted, quite possibly.
Would you really expect Sony to admit any fault with their mount though? Not likely. Theoretically they can make just about any lens, but they don't have the same freedom of design. Which we'll see as time goes on. There's a good reason Nikon's mount jumped by nearly 10mm from the DSLR to mirrorless.
 

Sator

EOS T7i
Oct 14, 2015
74
20
photonicshunkan.blogspot.com
Would you really expect Sony to admit any fault with their mount though? Not likely. Theoretically they can make just about any lens, but they don't have the same freedom of design.
Exactly. A Sony engineer gave a public talk in Japan in which he admitted that there was a heated debate within the company as to whether they should retro-convert their APS-C E mount into a 35mm format mount. That suggests that there were almost certainly dissenters amongst the Sony engineers who questioned the wisdom of doing this. It is quite possible (although this is speculative) that the decision to proceed with a 35mm format mount with APS-C dimensions was made more by the marketing department wanting to draw first blood over Canon and Nikon and that the engineers were overruled.

Naturally, the marketing department at Sony will not admit to any errors. However, it is rather damning to think that three firms founded APS-C mirrorless mounts around the same time: Canon (M mount), Sony (NEX/E mount), and Fuji (X mount)—but only one of these companies has retro-converted their APS-C mount into a 35mm format mount. Other firms could have designed a 35mm mount with APS-C dimensions but none have. Leica hasn't, nor has Sigma, Panasonic, Canon, or Nikon. That's a lot of engineers from lots of firms across the world to shun the Sony approach. Sony is out on a limb, totally isolated, leaving its marketing department to predictably spin the supreme wisdom of their decision.

Sadly, I rather fear that the success of the Sony FE mount represents the success of marketing strategy over good engineering.
 
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SecureGSM

2 x 5D IV
Feb 26, 2017
1,740
666
"... This ‘glass at the rear’ design is what allows this lens to be both shorter and lighter than other 70-200mm lenses...".

the above suggests that RF 400 F2.8 lens can be much lighter than EF 400 F2.8 III. I am thinking around 2.3kg ???
 

Sator

EOS T7i
Oct 14, 2015
74
20
photonicshunkan.blogspot.com
I love this diagram and explanation, but Sony has stated repeatedly that the mount diameter doesn't limit their lens design.
Of course, Sony would claim this. Sony issued this denial only with respect to the particular concern that the FE mount would not be able to support ultra-wide apertures. That is NOT the criticism of an ASP-C dimension 35mm format mount that Canon has come up with. The Canon internal R&D department state that they found that if they retro-converted their M mount into a 35mm format mount that it had negative repercussions on the ergonomics of the lens, making it front heavy, and requiring extra corrective elements i.e. a small and cramped mount means larger, more expensive, imbalanced and front heavy lens.

Fuji has also come up with similar criticism of the Sony FE mount based on what they call the "value angle" which simply implies that the dimensions of the FE mount hinder good lens design. This has also been recently the subject of a thread here:


Clearly, it was hardly in Fuji's self-interest to come up with this concept (although it won't stop Sony fanboys from dismissing it as self-interested Fuji propaganda). But it probably represents a fair consensus statement of what engineers within the optics industry overall think of the Sony FE mount.

Again, if retro-converting an APS-C mount into a 35mm format mount was such a fantastic idea (as Sony will predictably claim) then Canon would not have bothered spending a lot of time and money starting a new mount system from scratch, with Nikon independently coming up with its Z mount with almost an identical mount diameter to Canon.
 
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Sator

EOS T7i
Oct 14, 2015
74
20
photonicshunkan.blogspot.com
One more critical point. It is in Sony's vested self-interest to claim that a 35mm mount with APS-C dimensions presents no optical engineering limitations. It is in Canon's vested self-interest to claim that their time and effort in developing a new 35mm mirrorless mount with optimal dimensions has been worth it and the result of a superior engineering decision. Which should we believe?

The answer is we need an independent assessment of these rival claims. That's why Roger's statement, which I repeat again, is so important:

Canon claims that the shorter back focus distance with a wider opening allows them to place larger elements closer to the sensor to achieve this. The fact that the rear element is a large aspheric with subwavelength coating, and that the other rear elements are large, supports this.

This should not be read as Roger definitively endorsing Canon's engineering department, but it is a tentative first step towards that. I think, watch this space.

As an aside, this is bad news for those interested in third party lenses for the RF mount. The Sigma CEO has said that they need to make their lenses work for all mounts starting with the most restrictive one, which in this case is the Sony FE mount. That means that Sigma won't be able to place large lens elements near the sensor for any of their native mirrorless 35mm format lenses. The limitations of the Sony FE mount will be endemic to both the Canon and Nikon versions of their mirrorless lenses. Ouch.
 
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SecureGSM

2 x 5D IV
Feb 26, 2017
1,740
666
actually, Roger then went to say:

This ‘glass at the rear’ design is what allows this lens to be both shorter and lighter than other 70-200mm lenses.

which is quite a statement. so here is the confirmation you were looking for. right there.
 

koenkooi

EOS 7D MK II
Feb 25, 2015
737
495
[..]
As an aside, this is bad news for those interested in third party lenses for the RF mount. The Sigma CEO has said that they need to make their lenses work for all mounts starting with the most restrictive one, which in this case is the Sony FE mount. That means that Sigma won't be able to place large lens elements near the sensor for any of their 35mm format lenses. The limitations of the Sony FE mount will be endemic to both the Canon and Nikon versions of their mirrorless lenses. Ouch.
I wonder if they'll stick with that for their L mount designs and if not, will they offer them in RF and Z and leave out FE?
 

Larsskv

EOS 6D MK II
Jun 12, 2015
821
257
I wonder if they'll stick with that for their L mount designs and if not, will they offer them in RF and Z and leave out FE?
Good question. They have to consider making a lens that isn’t compatible with Sony, if the design advantage by ditching Sony is significant...
 

geffy

EOS M50
Jun 24, 2019
43
25
Very informative. Enlightening, even!

I do have a great relationship with my ef 70-200mm f/2.8L IS II. But it doesn't like the EOS R, mostly because of balance issues. Almost like they weren't made for each other. :rolleyes: I have a very hard time getting sharp shots with the combo in vertical orientation, though other lenses on the R are great, and the ef 70-200mm on my 5D IV is great. But, wow, do my hands get awkward and wobbly with the R and the ef version.

If this is beautifully balanced on the R, does this give us an indication that future R bodies will have similar ergonomics?


But as long as I have my 5DIV, I cannot justify ditching the ef lens.



Great teardown and discussion of what hopefully is a great new lens.
A fellow pro use the grip and swears it makes it more like a dslr but its more weight and a single battery life is awesome anyway
 

YuengLinger

EOS 5D MK IV
Dec 20, 2012
2,825
1,053
Southeastern USA
A fellow pro use the grip and swears it makes it more like a dslr but its more weight and a single battery life is awesome anyway
I thought about the grip, and I like the idea of more mass to balance longer ef lenses (which have the extra length from the adapter). But I'm not sure, when shooting in vertical orientation, my thumb would reach the upper-right part of the back LCD for Touch and Drag. Somebody else on this forum suggested a firmware update could switch the active AF area of the LCD (like the AF point can automatically switch in portrait orientation), but as yet it is only a suggestion.

I'm not taking away anything from the ef 70-200mm f/2.8L IS II. It's great. Some of my best shots. But it just gets wobbly when vertical on the R--in my small-medium size hands.
 

jdavidse

EOS T7i
Sep 13, 2012
71
60
This is the reason I sold my EF 70-200 and and got the RF 70-200. While a great lens, the length and unwieldliness on the R was just a bridge too far. The RF is night and day a better lens to handle, and of course it comes with me a lot more often.

As for the 5D IV, I’m keeping it for now but I don’t think it’s as strong as the R for the uses I use the 70-200 for. Tracking, focus speed, sharpness are all a lot better on the R with the RF lens. It’s like night and day.

All that said, the RF is flawed- it has the front focus issue at MFD. Mine has been to Canon and back but they won’t admit to finding anything. I hope we will see a firmware fix in the near future; I am taking a gamble in keeping the lens because MFD isn’t something I shoot at a whole lot.

Very informative. Enlightening, even!

I do have a great relationship with my ef 70-200mm f/2.8L IS II. But it doesn't like the EOS R, mostly because of balance issues. Almost like they weren't made for each other. :rolleyes: I have a very hard time getting sharp shots with the combo in vertical orientation, though other lenses on the R are great, and the ef 70-200mm on my 5D IV is great. But, wow, do my hands get awkward and wobbly with the R and the ef version.

If this is beautifully balanced on the R, does this give us an indication that future R bodies will have similar ergonomics?


But as long as I have my 5DIV, I cannot justify ditching the ef lens.



Great teardown and discussion of what hopefully is a great new lens.
 
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Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
I finally switched from Nikon to Canon because of this lens. Five figures of Ebay sales in the last month.

This lens at 70mm is a great one to have around the house and kids. A totally different mission than an old 70-200 horse's leg. A 35mm pancake (or wide zoom) to supplement, and this could be the new "main zoom." Ideal wedding lens?
 
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cayenne

EOR R
Mar 28, 2012
2,122
222
I finally switched from Nikon to Canon because of this lens. Five figures of Ebay sales in the last month.

This lens at 70mm is a great one to have around the house and kids. A totally different mission than an old 70-200 horse's leg. A 35mm pancake (or wide zoom) to supplement, and this could be the new "main zoom." Ideal wedding lens?
Impressive on the sales!!
I'd be very interested in seeing your work.....any links?
 
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Optics Patent

Former Nikon (Changes to R5 upon delivery)
Nov 6, 2019
310
248
Impressive on the sales!!
I'd be very interested in seeing your work.....any links?
I'm not selling photos. I'm selling Nikon equipment. :)

I'm an amateur shooter who has been published and won awards, but my photography is personal family stuff mostly. I'm a patent lawyer who specializes in part in optics, and also an inventor in the digital photography space.
 
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geffy

EOS M50
Jun 24, 2019
43
25
I received this message this morning on my cellphone while doing a quick search. Take it for what it's worth.

According to tomy northrup this is just a fact of life with focusing and fast lenses, he has a workaround, maybe in the future things might be perfect but photography is a practical thing and if you pixel peep and complain you will miss taking that picture
 

SecureGSM

2 x 5D IV
Feb 26, 2017
1,740
666
According to tomy northrup this is just a fact of life with focusing and fast lenses, he has a workaround, maybe in the future things might be perfect but photography is a practical thing and if you pixel peep and complain you will miss taking that picture
Oh, you cannot be serious... what a bucket of bollocks. This has nothing to do with practicality. This is a US$2600 zoom lens.
 

geffy

EOS M50
Jun 24, 2019
43
25
Oh, you cannot be serious... what a bucket of bollocks. This has nothing to do with practicality. This is a US$2600 zoom lens.
I wonder if canon do not do a "fix" might cause you to question your opinion and improve your skills, the problem is probably with the technology which will improve as the body is just not up to the task and hence the lens might need the r2 or r3 to show its capabilities