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


I post too Much on Here!!
Jul 21, 2010
Then again, I might be reading the diagram wrong, as it seems to me there's a second aperture marked as SSP.
SSP is a fully-opened aperture stop that changes diameter with zooming. That’s how a constant aperture zoom lens maintains its constant aperture through the zoom range.


6D - 7D
Nov 22, 2018
What are the potential advantages in using the RF 70-200 f/2.8 over the recently released EF 70-200 f/2.8 III? Would the AF be faster? I don't get why Canon releases the 70-200 III and then another almost similar version a year later (albeit for the RF system)
At 70mm the back focus is 14mm, so it's native for ML. What are the other advantages?
Firstly the zoom scheme is different from EF. This lens has a variable dimension and for a ML is a great advantage.
Secondly in the patent there also an example for f4 version....


Jan 30, 2015
I thought the bigger RF lens mount allows the lens designer to move the heavier lens elements towards the side of the body. So Canon has not explored that design concept here.
The RF mount is the exact same size as the EF mount. Only the distance between the mount and sensor has been reduced. From what I've read, it does allow elements to be pushed towards the back of the lens, and less elements to be used overall so the lens would technically be lighter.

As to why Canon has not done that, given that they are the master of lenses, I will be more than happy to claim ignorance and simply accept that they most likely know what they're doing.


Jun 9, 2017
The RF mount still isn’t any bigger than the EF mount...
It‘s about the geometry I think. Solid angle is a lot greater than on the EF-Mount. Thus greater angles are accepted which corresponds to a smaller distance in between the last element and the sensor.
If you were being ironic, then I‘m sorry.


I post too Much on Here!!
Jul 21, 2010
Pardon, but I still don't get why there are both SP & SSP.
SP is the standard aperture diaphragm. But consider – f/number is focal length divided by aperture diameter. So, a 200mm f/2.8 lens needs a max aperture of ~71mm (200/2.8). Zoom a 70-200mm lens to 70mm, that lens could be f/1.0 (although that's an oversimplification, and even so it would entail all sorts of other optical problems). Regardless, the intent is a constant zoom. A 70mm f/2.8 lens needs a 25mm diameter max aperture, and focal lengths between 200mm and 70mm need max apertures between 71mm and 25mm. The SSP aperture stop creates that effective max aperture to maintain a constant f/2.8 at all focal lengths.


I'm New Here
Nov 29, 2018
I had the R and the 24-105/4 L on a two-week rental. Primarily, I used it for wildlife, with some landscape and running border collies thrown in.

Much of the wildlife was flying bald eagles, fishing for salmon, and most of the time the lens was the 500/4 Lii, sometimes with the 1.4x and sometimes not. This is a demanding subject, under adverse conditions of cold, wind and low light. The R performed very well, focusing very accurately whenever I did my part of the job well. Sure, a higher frame rate would have been nice, as it would for fast, unpredictable action in sports. But the camera was capable of doing the job. I imagine something will be coming along in the not too distant future which will be more capable for sports and high action.

Before sending the camera back, I took it out for a little torture test. I put the 2xiii on the 100-400 L ii and went to the local duck pond to try get some photos of ducks in flight. I had to bump the ISO up much higher than I would have liked to get a decent shutter speed for something moving as fast as a duck, but the camera was capable of picking up focus and locking on. It was not easy, but then this subject never is, and focus was noticeably slower. But if you prefocused to near the correct distance of the incoming ducks, the camera could pick them up and deliver an in focus photo.

Part of the torture test was the background of the duck pond. It is little aspens, pines and willows--a very dense and busy background. Sasquatch could be napping in there. I chose it because it would be a very difficult situation for the autofocus to work, and work it did. The EVF also worked well. I was surprised, actually. An OVF would still be better in this situation but the R still did the job and is a testament to how good its EVF is. That said, the EVF could still be better, more pixels and faster refresh. Maybe the next generation, a year or two down the road.

I will not be buying the R, but I am impressed. I wanted to see if mirrorless could meet my needs. My only real disappointment was not getting to use it in extreme cold, minus 20 to minus 40, to see if and when the touch interface failed, The coldest I worked with the camera was minus 11F. It worked fine at that temp. If the next RF camera more closely meets my needs, I will be buying.
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Kodak Brownie
Aug 25, 2015
London, UK
This doesn't look like an L lens to me.

Compare it with the optical formula of the EF 70-300 IS II, it's not identical but it's similar in number and layout of elements.

This is a design for a (relatively) cheap lens - a budget RF 70-200 f/2.8 IS

I also don't think such a lens would come to market. I think far more likely would be a slower 70-300 type variant of the design. But who knows!


6D - 7D
Nov 22, 2018
Joly, it's similar for the type of zoom (variable size), BUT it's 2.8 and fixed 2.8!
So, it cannot be similar, just only for fixed aperture


Jul 28, 2015
Part of me really wants RF telephoto be painted black. But I doubt Canon would give up their iconic white paint job for marketing purposes.
i worked the college football playoffs at the orange bowl last week, big whites still dominate
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