# Patent: Optical formulas for a trio of wide f/1.8 prime lenses for the RF-S mount



## Canon Rumors Guy (Aug 22, 2022)

> A new patent showing off some lens element coating to help with ghosting and other anomalies has appeared alongside optical formulas for what appears to be RF-S prime lenses.
> Below are the three prime lens designs shown in the patent, we wouldn’t be surprised for one of these to hit the market as a consumer product.
> Canon RF-S 21mm f/1.8
> 
> ...



Continue reading...


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## BakaBokeh (Aug 22, 2022)

Recently been using my M50 more. Love the size and compactness of not just the body, but the lenses. More fast RF-S lenses would definitely make me want to upgrade to the RF-S if the size stays compact.


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## entoman (Aug 22, 2022)

Canon Rumors Guy said:


> Continue reading...


Is there such a thing as an "RF-S mount"? 

I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?

Or have I got it wrong?


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## EOS (Aug 22, 2022)

RF-S but no RF (sigh)


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## unfocused (Aug 22, 2022)

entoman said:


> Is there such a thing as an "RF-S mount"?
> 
> I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?
> 
> Or have I got it wrong?


That's correct. However, I expect we will see a lot of people/sites referring to RF-S lenses as having an RF-S "mount." Not entirely accurate, but Canon Rumors has never claimed to be a research paper.


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## EverydayPhotographer (Aug 22, 2022)

unfocused said:


> That's correct. However, I expect we will see a lot of people/sites referring to RF-S lenses as having an RF-S "mount." Not entirely accurate, but Canon Rumors has never claimed to be a research paper.


Maybe it's because Canon in their own material refers to it as the "RF-S Mount?" (See link: https://www.usa.canon.com/shop/p/rf-s18-150mm-f3-5-6-3-is-stm?color=Black&type=New) 

They do also specifically mention that it fits on full frame cameras in crop mode. "This lens was designed with smaller APS-C sensors in mind, and when attached to a full frame EOS R camera, automatically enables the 1.6x crop mode. It offers 100% x 100% Dual Pixel CMOS AF coverage for APS-C sensors, and 80% x 80% Dual Pixel CMOS AF coverage for Full Frame sensors (in crop mode)."


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## unfocused (Aug 22, 2022)

EverydayPhotographer said:


> Maybe it's because Canon in their own material refers to it as the "RF-S Mount?" (See link: https://www.usa.canon.com/shop/p/rf-s18-150mm-f3-5-6-3-is-stm?color=Black&type=New)
> 
> They do also specifically mention that it fits on full frame cameras in crop mode. "This lens was designed with smaller APS-C sensors in mind, and when attached to a full frame EOS R camera, automatically enables the 1.6x crop mode. It offers 100% x 100% Dual Pixel CMOS AF coverage for APS-C sensors, and 80% x 80% Dual Pixel CMOS AF coverage for Full Frame sensors (in crop mode)."


Good point. If I were Canon I'm not sure I would refer to it as an RF-S "mount," but it's their company and they can do what they want. (I'm not sure how I would refer to the mount though.) Regardless, it's kind of an esoteric and pointless distinction, which is perfect for forum discussions.


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## EverydayPhotographer (Aug 22, 2022)

unfocused said:


> Good point. If I were Canon I'm not sure I would refer to it as an RF-S "mount," but it's their company and they can do what they want. (I'm not sure how I would refer to the mount though.) Regardless, it's kind of an esoteric and pointless distinction, which is perfect for forum discussions.


Interestingly, looking at the tech specs for the R10, they refer to the lens mount as the RF lens mount, and then under "compatible lenses" refer to the "Canon RF-S/RF lens group"


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## mxwphoto (Aug 22, 2022)

Calling it a RF-S mount is more clear and better than calling it RF mount but for crop sensor cameras. I think Canon did the same for EF-S lenses as well. This makes things less ambiguous and provides clear delineation from RF full frame lenses.

I would imagine Canon most likely coming out with the 28mm (45mm equiv) but they could also spring for the 20mm (33mm equiv). Doubtful there's space for all 3 though.


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## Tom W (Aug 22, 2022)

EOS said:


> RF-S but no RF (sigh)


Well, a 24 f/1.8 RF lens is about ready to hit the streets, so there is that.


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## unfocused (Aug 22, 2022)

mxwphoto said:


> Calling it a RF-S mount is more clear and better than calling it RF mount but for crop sensor cameras. I think Canon did the same for EF-S lenses as well. This makes things less ambiguous and provides clear delineation from RF full frame lenses.
> 
> I would imagine Canon most likely coming out with the 28mm (45mm equiv) but they could also spring for the 20mm (33mm equiv). Doubtful there's space for all 3 though.


I think the (very minor) distinction here is that EF-S lenses were clearly a different "mount" that could not be placed on a full-frame body, whereas all RF lenses, whether RF-S or RF, can be mounted on any R body. Thus in a technical sense it's not really a different "mount." However, it's really an esoteric discussion.


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## mxwphoto (Aug 22, 2022)

unfocused said:


> I think the (very minor) distinction here is that EF-S lenses were clearly a different "mount" that could not be placed on a full-frame body, whereas all RF lenses, whether RF-S or RF, can be mounted on any R body. Thus in a technical sense it's not really a different "mount." However, it's really an esoteric discussion.


Indeed the masses won't care much on the merits of this debate, relegating it to rumor mill discussion posts.

While we are discussing technicalities, I would like to add that EF-S can be mounted on a full frame DSLR successfully if the mirror is in lock-up mode/silent shutter engaged. It would be good for video recording or one photo before you have to remove the lens to prevent the mirror slap damage.


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## David - Sydney (Aug 22, 2022)

Still no ultra wide angle RF-S lenses though.
IMHO, RF-S lenses will be made to suit the build/cost/etc level of the lower end R mount bodies so f1.8 seems to be different to that assumption. 

I would be very surprised to see a RF-S lens that was L quality for instance. Has any EF-S lens been wider than f2.8?


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## EverydayPhotographer (Aug 23, 2022)

f/2.8 was the fastest that the EF-S mount got. But Canon did release the 22mm f/2.0 and 32mm f/1.4 in the EF-M lineup.


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## Avenger 2.0 (Aug 23, 2022)

Strange lenses. So a fullframe equivalent 34mm, 38mm and 45mm  Or will they just pick one for mass production and never produce the rest?


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## f119a (Aug 23, 2022)

Avenger 2.0 said:


> Strange lenses. So a fullframe equivalent 34mm, 38mm and 45mm  Or will they just pick one for mass production and never produce the rest?


They are not aps-c lenses and that 24/1.8 is apparently what you get on the market. 
Check half angle of view.


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## f119a (Aug 23, 2022)

entoman said:


> Is there such a thing as an "RF-S mount"?
> 
> I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?
> 
> Or have I got it wrong?


the CR guy got them wrong.
We checked this patent like a month ago and the 24mm design is the current RF24


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## Chaitanya (Aug 23, 2022)

Would like to see replacements for EF-S 10-18, 35mm and 60mm lens for RF-S along with tele zoom(longer than 55-250mm) lens.


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## Bob Howland (Aug 23, 2022)

Chaitanya said:


> Would like to see replacements for EF-S 10-18, 35mm and 60mm lens for RF-S along with tele zoom(longer than 55-250mm) lens.


Would porting most/all the m-mount lenses to rf mount suffice?


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## LogicExtremist (Aug 23, 2022)

Chaitanya said:


> Would like to see replacements for EF-S 10-18, 35mm and 60mm lens for RF-S along with tele zoom(longer than 55-250mm) lens.


The EF-S 10-8mm and 55-250mm were lenses that punched well above their weight, and provided great image quality for their price. Even if Canon didn't put metal lens mounts on either (to remind buyers they're using a cheaper lens)  those lenses really delivered. It would be great to see RF-S versions with some kind of improvements (and not darker in aperture) at such good prices.


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## LogicExtremist (Aug 23, 2022)

Bob Howland said:


> Would porting most/all the m-mount lenses to rf mount suffice?


Why not port the best of EF-S *and *EF-M to RF-S? Even better, with improvements, even minor ones. Making the new RF-S platform better than either of its predecessors would be a positive development and a step in the right direction. The other possibility is that they could make minimal effort and put out the least number of lenses possible because they just want to sell expensive premium gear as it's more profitable.


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## Bob Howland (Aug 23, 2022)

LogicExtremist said:


> Why not port the best of EF-S *and *EF-M to RF-S? Even better, with improvements, even minor ones. Making the new RF-S platform better than either of its predecessors would be a positive development and a step in the right direction. The other possibility is that they could make minimal effort and put out the least number of lenses possible because they just want to sell expensive premium gear as it's more profitable.


"Porting" M-mount and EF-S lenses means two different things. Current owners of EF-S lenses can "port" those lenses with a $100 adapter. Porting an M-mount lens is both simpler and more complicated. All you have to do is look at pictures of the two 18-150 lenses side-by-side to see why.


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## LogicExtremist (Aug 23, 2022)

Bob Howland said:


> "Porting" M-mount and EF-S lenses means two different things. Current owners of EF-S lenses can "port" those lenses with a $100 adapter. Porting an M-mount lens is both simpler and more complicated. All you have to do is look at pictures of the two 18-150 lenses side-by-side to see why.


I meant exactly what you meant, not adapting, but porting, that is, taking all the front lens element group optics and adding the necessary rear lens element group to optimise it for the RF-S mount.


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## EOS 4 Life (Aug 23, 2022)

David - Sydney said:


> Still no ultra wide angle RF-S lenses though.
> IMHO, RF-S lenses will be made to suit the build/cost/etc level of the lower end R mount bodies so f1.8 seems to be different to that assumption.
> 
> I would be very surprised to see a RF-S lens that was L quality for instance. Has any EF-S lens been wider than f2.8?


The current non-L full-frame f/1.8 prime lenses are fairly cheap.
I would expect APS-C versions to cost significantly less.
I would not expect them to be L quality either.

Primes of f/2.8 and f/3.5 would not surprise me either.


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## Chaitanya (Aug 23, 2022)

EOS 4 Life said:


> The current non-L full-frame f/1.8 prime lenses are fairly cheap.
> I would expect APS-C versions to cost significantly less.
> I would not expect them to be L quality either.
> 
> Primes of f/2.8 and f/3.5 would not surprise me either.


16mm f2.8 is a great option for APS-C RF bodies its cheap, small and has decent max mag ratio.


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## BakaBokeh (Aug 23, 2022)

Bob Howland said:


> Would porting most/all the m-mount lenses to rf mount suffice?


That would be a good start. The 22m f2 and 32mm f1.4 blows my mind how I can have these fast apertures in a small package. I was very hopeful for more. If they do port these over to RF-S hopefully, they can build on it and develop more fast primes at other focal lengths.


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## EOS (Aug 23, 2022)

Tom W said:


> Well, a 24 f/1.8 RF lens is about ready to hit the streets, so there is that.


Is that the RF 24mm IS STM Macro? Not exactly the 24mm L we’ve been waiting for. ¯\_(ツ)_/¯


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## SnowMiku (Aug 24, 2022)

Bob Howland said:


> Would porting most/all the m-mount lenses to rf mount suffice?


I'm thinking that could be the plan, port all of the EF-M lenses to RF-S and then if demand goes down on EF-M too much in a few years time then RF-S will be the direct replacement.


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## SnowMiku (Aug 24, 2022)

LogicExtremist said:


> The EF-S 10-8mm and 55-250mm were lenses that punched well above their weight, and provided great image quality for their price. Even if Canon didn't put metal lens mounts on either (to remind buyers they're using a cheaper lens)  those lenses really delivered. It would be great to see RF-S versions with some kind of improvements (and not darker in aperture) at such good prices.


The plastic mounts personally never bothered me. It would be nice to see RF-S lenses being improved over the EF-S and EF-M versions but unfortunately I think they are going to have less range and be darker such as the RF-S 18-45mm F4.5-6.3 IS STM vs EF-M 15-45mm f/3.5-6.3 IS STM vs EF-S 18-55mm F/3.5-5.6 IS STM.


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## neuroanatomist (Aug 24, 2022)

SnowMiku said:


> The plastic mounts personally never bothered me. It would be nice to see RF-S lenses being improved over the EF-S and EF-M versions but unfortunately I think they are going to have less range and be darker such as the RF-S 18-45mm F4.5-6.3 IS STM vs EF-M 15-45mm f/3.5-6.3 IS STM vs EF-S 18-55mm F/3.5-5.6 IS STM.


I think most will be identical, like the RF-S 18-150 and EF-M 18-150. 

The standard zoom lens was an exception, IMO, required because the EF-M 15-45 was not a retrofocal design with the 18mm flange focal distance on M, but would need to be with the 20mm distance on R. The other EF-M designs should port over directly.


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## Bob Howland (Aug 24, 2022)

LogicExtremist said:


> I meant exactly what you meant, not adapting, but porting, that is, taking all the front lens element group optics and adding the necessary rear lens element group to optimise it for the RF-S mount.


If Canon follows Sigma's example, there won't be any rear element group. They'll just extend the rear of the lens and effectively make the adapter a permanent part of the lens.


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## neuroanatomist (Aug 24, 2022)

Bob Howland said:


> If Canon follows Sigma's example, there won't be any rear element group. They'll just extend the rear of the lens and effectively make the adapter a permanent part of the lens.


I highly doubt Canon will release RF-S lenses that are simply EF-S lenses with 24mm of empty barrel at the rear. EF-M lenses, yes – a new barrel and mount with the same optics inside will work for most of them.


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## amfoto1 (Aug 24, 2022)

entoman said:


> Is there such a thing as an "RF-S mount"?
> 
> I thought that "RF-S" lenses would fit on normal RF mount, as well as on crop cameras, but that full-frame models would electronically recognise RF-S lenses, and crop the frame accordingly?
> 
> Or have I got it wrong?


There is no RF-S mount... But there are RF-S lenses.
With their DSLRs Canon felt the needs to prevent the "crop only" lenses from being fitted to their full frame cameras. Remember that at the time, in 2004, Canon was almost the only company making both APS-C and full frame cameras (Nikon had made one full frame by then, if I remember correctly). So the distinction may have been more necessary. 
Today most photographers advanced enough to be buying interchangeable lens cameras understand the distinction. Plus with mirrorless there is no concern about possible interference between the rear element of the lens and a moving mirror, as there could have been with DSLRs. 
So there is no need for a distinct mount with the R-series. But there is still need for at least some "crop sensor designed" lenses, which Canon is designating RF-S.


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## amfoto1 (Aug 24, 2022)

I am not so sure these patents are for RF-S lenses. I think they may be full frame capable RF.

The reason I think so is the stated "half angle of view" of each lens. Take the 24mm as an example. A full frame 24mm lens has roughly 82 degree angle of view and the patent states exactly half that: 41 degrees.

Why do you think these are RF-S lenses?

Further, I think the most likely next RF-S lens would be an ultrawide zoom and there has been a 10-24mm on the official RF lens roadmap since the beginning.

Plus, I would hope Canon simply incorporates some of the very good EF-M lens optical designs, such as the 22mm f/2 "pancake". However, it's not just a matter of putting the EF-M optics into a new RF barrel. The EF-M back focus is shorter than the RF mount. EF-M is 18mm while RF is 20mm. So some tweaking will be required. (The back focus on EF & EF-S is 44mm, leaving plenty of room... 24mm... for an adapter.)


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## neuroanatomist (Aug 25, 2022)

TL;DR - these are RF lenses, not RF-S (but not for the reason suggested by @amfoto1 )



amfoto1 said:


> I am not so sure these patents are for RF-S lenses. I think they may be full frame capable RF.


I agree that these are RF (full frame) designs, but not for the reason you suggest.



amfoto1 said:


> The reason I think so is the stated "half angle of view" of each lens. Take the 24mm as an example. A full frame 24mm lens has roughly 82 degree angle of view and the patent states exactly half that: 41 degrees.


That’s why it’s called a _half_ angle of view. Canon’s optical design patents specify angles, element curvatures, etc., for just half a lens because lenses designs are symmetrical. A lens design with a specified half angle of view of 41° has a full AoV of 82° as you’d expect for a 24mm lens.

Also, lens design parameters like focal length and AoV (or hAoV) are intrinsic to the lens – they don’t get adjusted based on the sensor size for which the lens is intended.



amfoto1 said:


> Why do you think these are RF-S lenses?


They are suggested to be RF-S because of the image height, which is the radius of the image circle (1/2 the diagonal of the intended sensor). A FF sensor has a 43.2mm diagonal, meaning FF lens designs have an image height of 21.6mm. These designs all fall short of that value, meaning the image circles won’t fully cover a FF sensor. 

However, an APS-C image circle is 31.2mm in diameter, meaning a 15.6mm image height – these lenses all have images circles too big for APS-C. In wide angle lenses like these, the image circle is limiting (it’s not for telephoto lenses, which is why there aren’t EF-S telephoto lenses). If these are RF-S lenses, too-large image circles mean lenses that are unnecessarily larger and heavier. Canon may not care about that, but more glass and more plastic than minimally needed means higher production costs and thus lower profits – and for damn sure Canon cares about that. 

Some time back, CRguy posted about patents for RF APS-C pancake lenses. The lens that CRguy called an RF-S 16mm f/2.8 has an image height of 18.2mm, and in fact that patent design is the RF 16mm f/2.8 lens that can be purchased today (which is obvious when the lens diagram from the patent example is superimposed on the block diagram of the actual RF lens). 

The reason the image circle can be too small for FF is that the lenses have significant geometric (barrel) distortion in the design. Correcting barrel distortion stretches the corners of the image, so after correction the FF corners will be filled in, just as they are on the 16/2.8.


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## Czardoom (Aug 25, 2022)

LogicExtremist said:


> Why not port the best of EF-S *and *EF-M to RF-S? Even better, with improvements, even minor ones. Making the new RF-S platform better than either of its predecessors would be a positive development and a step in the right direction. The other possibility is that they could make minimal effort and put out the least number of lenses possible because they just want to sell expensive premium gear as it's more profitable.


Or the other - perhaps most likely alternative - is that they could make minimal effort and produce less RF-S lenses because they know from past experience and market research, that the target consumer for crop cameras is either an entry level consumer looking for only the basic lenses and wants them cheap in price, or they are birders and wildlife shooters who will be buying RF not RF-S lenses.


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## masterpix (Aug 27, 2022)

unfocused said:


> That's correct. However, I expect we will see a lot of people/sites referring to RF-S lenses as having an RF-S "mount." Not entirely accurate, but Canon Rumors has never claimed to be a research paper.


It is the same like the older EF and EFs which has the same mount but different "image width". As the EF and EFs also somewhat differ cause in the EFs it was able to "penetrate" deeper into the camera mount for the APS-C mirror was a bit smaller and therefore left bit more room inside. In the case of the RF, it won't be as such for the space behind the mount it similar in all models. So the RFs lenses differs from the RF is by the "image width" alone.


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## neuroanatomist (Aug 28, 2022)

Just in case there was any doubt that the lenses in this patent are RF lenses and not RF-S lenses, here is the 24mm f/1.8 diagram from the lens patent:



And here is the block diagram of the RF 24mm f/1.8 lens that is now available for purchase.


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## chasingrealness (Nov 8, 2022)

I decided to take the plunge and buy the R7 today. Professional obligations are increasing again and while I’ve always found my RP adequate for all my client work to date?m, two bodies, multiple card slots, and light video capabilities are a must for my second body. I’m just glad the R7 exists during this time that I’m priced out of anything more premium.


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