The benefits of the large diameter of the EOS R’s RF mount explained

4fun

picture? perfect!
Nov 19, 2018
181
53
What I’m seeing with all the illustrations here, and elsewhere, is an exaggeration of the size of elements for lens designs for mirrorless. The reality isn’t so exaggerated.
not sure about this - whether or not illustrations and images truly "to scale" ... or not.

illustration and images of the 2 lenses seem to correspond pretty well. does not look "exaggerated" to me.




waiting to read reports of "scratched rear lenses". oO
 

jd7

EOS 7D MK II
Feb 3, 2013
741
107
actually, the diameter *IS* very important. it's a combination of lens registration distance and mount diameter that gives the flexibility.

which is why they didn't use the EF-M mount. they could use the EF-M mount, and the article states that Canon even considered it.

the larger mount diameter allows them to "flip" the elements around, and not use an element to "spread" the light across the entire sensor.

This is why when I wrote CN's article, I compared the RF lens to a similar Sony FE lens, and the differences are as Canon discussed in their presentation.
Agree with all of that but I think there has been some confusion around the internet about whether the RF mount is larger than the EF mount. I've seen a few people claim that it is, but of course it isn't - it's the same size as the EF mount. I'm guessing that a few people have jumped to the conclusion that since Nikon just introduced a FF mirrorless camera with a mount larger than its previous FF mount, Canon must have done the same thing with their new FF mirrorless. Anyway, my assumption is the earlier posters were picking up on the sorts of claims I've seen elsewhere and feeling like references to the new RF mount being "large" tend to reinforce that misinformation. Your point is quite different though of course - you are just saying the EF/RF mount is larger than the EF-M mount.
 
  • Like
Reactions: Viggo

4fun

picture? perfect!
Nov 19, 2018
181
53
Your point is quite different though of course - you are just saying the EF/RF mount is larger than the EF-M mount.
more importantly:
* Canon EF and R mount parameters [combo of throat width and flange focal distance] are very well chosen for FF image circle.
* Sony E-mount is well chosen for APS-C sensor image circle but a very poor choice for FF sensors.
* Nikon Z mount looks a bit of overkill for throat width. Apparently Nikon wanted to have potential for some exotic ultra-fast "showcase" glass [eg manual focus f/0.95 lenses]. Regular lenses will generally not profit from it.
* Canon EF-M is perfectly chosen for APS-C sensor [Canon 1.6x] but would be a very bad choice for FF image circle.

Agree with all of that but I think there has been some confusion around the internet about whether the RF mount is larger than the EF mount. I've seen a few people claim that it is,
Folks who don't even know the basic mount parameters [not you!] should first read up on the subject before posting.
 
  • Like
Reactions: Ah-Keong

LDS

EOR R
Sep 14, 2012
1,578
152
since Nikon just introduced a FF mirrorless camera with a mount larger than its previous FF mount
Nikon was still constrained by compatibility with its old F mount. Canon broke compatibility with the previous FD mount more than 30 years ago and increased the diameter back then. Going even larger would mean also larger cameras, or a new camera design. And may be not needed (yet?)
 
Aug 22, 2010
1,621
317
48
Uk
www.GMCPhotographics.co.uk
I was surprised to see the ef 85mm f1.4 LIS launched. I was expecting a slew of new f1.2 lenses (24mm / 35mm / 50mm and 85mm). So I wonder if Canon are holding back the f1.2 feature for the R mount lenses. Purely for a marketing purpose (there really isn't a technical or optical reason).
 

4fun

picture? perfect!
Nov 19, 2018
181
53
I was surprised to see the ef 85mm f1.4 LIS launched. I was expecting a slew of new f1.2 lenses (24mm / 35mm / 50mm and 85mm). So I wonder if Canon are holding back the f1.2 feature for the R mount lenses. Purely for a marketing purpose (there really isn't a technical or optical reason).
but there is a fairly compelling economic reason. Even in the past a few drooled over f/1.2 lenses, but only very few were sold ... compared to more sensible lens alternatives. Now, with EOS R system launched, exotic-expensive EF lenses will be an even harder sell. So I would not hold my breath for any new/additional f/1.2 EF lenses. As a matter of fact I expect hardly any new/additional EF lenses to appear.
 
Mar 14, 2012
2,301
189
but there is a fairly compelling economic reason. Even in the past a few drooled over f/1.2 lenses, but only very few were sold ... compared to more sensible lens alternatives. Now, with EOS R system launched, exotic-expensive EF lenses will be an even harder sell. So I would not hold my breath for any new/additional f/1.2 EF lenses. As a matter of fact I expect hardly any new/additional EF lenses to appear.
The f/1.2 lenses sold more than "very few." They were staples for event and portrait photographers.
 

criscokkat

EOS RP
Sep 26, 2017
266
232
Madison, WI
It's only a mater of time before less expensive Ti7 level cameras are produced using the RF mount. With judicious use of plastic and the sizes of the elements the lenses could be made cheaper, especially if they use a smaller sensor size. Add in the existing aps-c sensors or a new line of aps-h sensors to differentiate between full frame and consumer RF mount cameras and it gets even cheaper.

A aps-h sized sensor might even be a great fit with a 7dII replacement. Less data to process, still less detail than a 1dx replacement.
 
Last edited:
  • Like
Reactions: Ah-Keong

4fun

picture? perfect!
Nov 19, 2018
181
53
Doesn't seem to have prevented the too expensive part :)
oh well ... .:)

Will have to wait and see how/as Canon RF lens portfolio develops. f/2 zoom and f/1.2 lenses are "premium products" = price carries a PREMIUM over value.
There will be more affordable RF lenses too.
 

melgross

EOS 7D MK II
Nov 2, 2016
407
217
not sure about this - whether or not illustrations and images truly "to scale" ... or not.

illustration and images of the 2 lenses seem to correspond pretty well. does not look "exaggerated" to me.




waiting to read reports of "scratched rear lenses". oO
Well, you’ll see right there, that the difference in rear element size isn’t that different. Assuming that the pics of both lenses are real. We’re seeing an exaggeration of what’s possible in the drawings of the lens designs.

It’s simple arithmetic. Look at the rear of your lens, and see the max diameter element that can fit, minus the metal construction of the lens barrel holding the lenses in place. It’s much smaller than the front elements of a number of current fast lenses. It’s a physical limitation. If they made the mount with a gigantic 70mm size, they could do it. But as it is, the mount is about the same dia as before, just a lot closer.
 

melgross

EOS 7D MK II
Nov 2, 2016
407
217
I was surprised to see the ef 85mm f1.4 LIS launched. I was expecting a slew of new f1.2 lenses (24mm / 35mm / 50mm and 85mm). So I wonder if Canon are holding back the f1.2 feature for the R mount lenses. Purely for a marketing purpose (there really isn't a technical or optical reason).
Canon has to be realistic about sales. With the new 50 1.2 going for $2,300, how many do they really expect to sell? That and the f2 zoom are more of a; “See what we can do!”. But to sell tens, and even hundreds of thousands of lenses, they need much lower pricing. Really, 1.4 is just a half stop slower, but lenses could cost just half of what the 1.2 versions could cost. F1.2 lenses have always been lenses we generally lusted over, but never bought new.
 
  • Like
Reactions: Kharan

Viggo

EOS 5D SR
Dec 13, 2010
4,213
774
I want all f1.2 lenses :LOL: okay, I can live with a 100mm in f1.4..

I like this thread:giggle::coffee:
 

bokehmon22

EOS RP
Oct 31, 2016
356
186
The new mount would unlock the development potential especially towards ultra-wide angle end. Would Sony "upsize" the mount? Would Canon scrap the EF-M mount?
I doubt it. I will be a big FU to their supporters, but I would love for that to happens.
 
  • Like
Reactions: Ah-Keong

Bob Howland

EOS 7D MK II
Mar 25, 2012
443
46
Small percentage of sales but that could be said of any L lens besides the kit lenses. A small percentage does not mean "a few."
Really?? Wild guess: There are five times as many 16-35 f/2.8, 24-70 f/2.8 and 70-200 f/2.8 IS lenses sold as there are any f/1.2 lens. Does anybody here have real data?
 

highdesertmesa

EOS T7i
Apr 17, 2017
57
20
CR guy didn't write the article, so he can't change it. Besides, you and degos misinterpret the point anyway.
They could have titled THIS article: "reduced flange distance combined with keeping the same, large mount diameter..." // This article title just keeps this false notion circulating that RF went up in diameter from EF.
 

melgross

EOS 7D MK II
Nov 2, 2016
407
217
Small percentage of sales but that could be said of any L lens besides the kit lenses. A small percentage does not mean "a few."
A few thousand, is a few compared to the 100 million EOS lenses Canon has sold over the years. Even the low tens of thousands would be regarded as few.
 

AlanF

Canon 5DSR II
Aug 16, 2012
5,756
3,091
A few thousand, is a few compared to the 100 million EOS lenses Canon has sold over the years. Even the low tens of thousands would be regarded as few.
Do you know how many f/1.2s have been sold? Without those figures, the discussion is meaningless.