# Patent: Canon RF APS-C pancake prime lens optical formulas



## Canon Rumors Guy (Jun 10, 2022)

> It looks like Canon will be bringing one or more RF-S prime lenses for the Canon EOS R7 and Canon EOS R10. One of the most requested RF-S lenses is unsurprisingly a pancake lens. Keith at Northlight Images uncovered a patent at the USPTO with what looks to be RF-S pancake optical formulas.
> None of these
> Canon RF-S 14mm f/2.8
> 
> ...



Continue reading...


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## Franklyok (Jun 10, 2022)

What does this “back focus” less than 20 mm say? RF flange distance is 20mm. 

Are the lens going to be inserted into mount pipe?


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## H. Jones (Jun 10, 2022)

A RF-S 10mm f/2.8 prime would be a super nice budget option for a lot of vloggers/etc. Equivalent to the RF 16mm F/2.8 but an even smaller and more compact option for APS-C. The RF 16mm is already really nice and small for full frame cameras, so I can imagine it would make sense for Canon to fill that role for their crop camera consumers.


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## neuroanatomist (Jun 10, 2022)

Canon Rumors Guy said:


> Image Height: 18.20mm


That's not APS-C. Closest would be Super35 or (gasp) APS-H.


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## Tom W (Jun 10, 2022)

Well, the full frame 16/2.8 is already pretty small, and I don't think it would be hard to pull the 22 over from the M series, with minimal alteration. But the 14 would make sense. Along with a 20 or 22 mm pancake.


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## unfocused (Jun 10, 2022)

neuroanatomist said:


> That's not APS-C. Closest would be Super35 or (gasp) APS-H.


Don’t get us excited.


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## entoman (Jun 10, 2022)

neuroanatomist said:


> That's not APS-C. Closest would be Super35 or (gasp) APS-H.


The specs state "RF-S" so they must be for APS-C models.

Maybe a misprint, but perhaps Canon has deliberately elected to have a larger than normal image circle with these wide-angle optics, in order to minimise vignetting and softness in the corners?

Or am I being daft?


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## hachu21 (Jun 10, 2022)

neuroanatomist said:


> That's not APS-C. Closest would be Super35 or (gasp) APS-H.


Maybe bigger image circle for ibis movement?


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## koenkooi (Jun 10, 2022)

hachu21 said:


> Maybe bigger image circle for ibis movement?


That would be my guess as well: make the lens cheap, use IBIS or EIS to make it better. This is why I preordered the R7 instead of the R10


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## Lee Jay (Jun 10, 2022)

"Unsurprisingly" a pancake lens? I find that, generally, the smaller the lens the hard the camera is to handle. Pancake primes are the worst as there's literally nothing to hold onto with your left hand. Why do people want these things? I thought it was only about price, not desirability.


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## neuroanatomist (Jun 10, 2022)

entoman said:


> The specs state "RF-S" so they must be for APS-C models.
> 
> Maybe a misprint, but perhaps Canon has deliberately elected to have a larger than normal image circle with these wide-angle optics, in order to minimise vignetting and softness in the corners?
> 
> Or am I being daft?


What 'specs'? If it's not in the patent, it's not a spec, it's a guess by Keith, CRguy or someone else.

But a larger image circle for IBIS makes sense.


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## entoman (Jun 10, 2022)

neuroanatomist said:


> What 'specs'? If it's not in the patent, it's not a spec, it's a guess by Keith, CRguy or someone else.
> 
> But a larger image circle for IBIS makes sense.


As you point out, the patent application makes no mention of "APS-C" or "RF-S".

The "specs" are, as you say, an informed guess - by a highly experienced commentator, Keith Cooper of Northlight.

I'd be extremely surprised if his guess was wrong.

If the larger image circle was purely to accommodate IBIS, I would have expected Canon to design *all* of its RF-S lenses to have this image circle, not just the pancakes under examination here.

I think it's more likely that the larger image circle has been chosen to minimise corner softness and vignetting, both of which are a bigger problem with wide-angle pancakes than with longer focal lengths.

But like Keith, I'm only guessing


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## Tom W (Jun 10, 2022)

neuroanatomist said:


> That's not APS-C. Closest would be Super35 or (gasp) APS-H.


Makes me wonder if the lenses couldn't be dual-purpose - APS-C and Super-35. Not a huge size difference there. I doubt they'll go for the 1.3X again. The purpose of that format no longer really exists.


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## entoman (Jun 10, 2022)

Lee Jay said:


> Why do people want these things? I thought it was only about price, not desirability.


Presumably to reduce size and weight when travelling, hiking or mountaineering.

A pancake takes up next to no room, and can even be carried in a pocket, to be available at all times.


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## Stig Nygaard (Jun 10, 2022)

H. Jones said:


> A RF-S 10mm f/2.8 prime would be a super nice budget option for a lot of vloggers/etc.


The headline on that lens/patent is wrong. It is an 18mm as it says in text below:

Focal Length: 18.20mm
Sorry :-/


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## neuroanatomist (Jun 10, 2022)

entoman said:


> Presumably to reduce size and weight when travelling, hiking or mountaineering.
> 
> A pancake takes up next to no room, and can even be carried in a pocket, to be available at all times.


Exactly. The M6 with M22mm fits in my coat or cargo pants pocket.

When going to an event where my primary lens was the 70-200/2.8, it was great to be able to drop the EF 40/2.8 into my pocket and swap on a normal focal length lens as needed (I typically carry with a BR strap attached to the lens foot, so the 70-200 could simply dangle from that as I shot with the 40 mm pancake) – it was a great, portable solution.

That’s not really an option with my R3, because having to carry both the adapter and the pancake lens defeats the purpose. I would definitely like a normal or wide (not ultrawide) pancake prime for RF full frame.


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## Rocky (Jun 10, 2022)

Lee Jay said:


> "Unsurprisingly" a pancake lens? I find that, generally, the smaller the lens the hard the camera is to handle. Pancake primes are the worst as there's literally nothing to hold onto with your left hand. Why do people want these things? I thought it was only about price, not desirability.


For very short ( pancake) lenses, you craddle the camera with your left hand


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## Lee Jay (Jun 10, 2022)

neuroanatomist said:


> Exactly. The M6 with M22mm fits in my coat or cargo pants pocket.
> 
> When going to an event where my primary lens was the 70-200/2.8, it was great to be able to drop the EF 40/2.8 into my pocket and swap on a normal focal length lens as needed (I typically carry with a BR strap attached to the lens foot, so the 70-200 could simply dangle from that as I shot with the 40 mm pancake) – it was a great, portable solution.
> 
> That’s not really an option with my R3, because having to carry both the adapter and the pancake lens defeats the purpose. I would definitely like a normal or wide (not ultrawide) pancake prime for RF full frame.


Okay, but how do you hold the camera? I usually hold the weight of the camera in my left hand by putting my left hand under the CG of the camera-lens combination, which is always somewhere along the length of the lens. With a small prime, the CG is in the body and there's no place for me to put my left hand. That leads to trying to hold the body with my left hand on the left edge of the body where there's no grip.


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## Lee Jay (Jun 10, 2022)

Rocky said:


> For very short ( pancake) lenses, you craddle the camera with your left hand


There's really nothing there to hold on to.


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## Jasonmc89 (Jun 10, 2022)

Lee Jay said:


> "Unsurprisingly" a pancake lens? I find that, generally, the smaller the lens the hard the camera is to handle. Pancake primes are the worst as there's literally nothing to hold onto with your left hand. Why do people want these things? I thought it was only about price, not desirability.


You know, you don’t _have_ to use a pancake lens..?

Slap that massive 50mm 1.2 on it if you want.


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## John Wilde (Jun 10, 2022)

Strictly speaking, Canon's strategy document shows that they should release about eight new lenses this year.


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## Jasonmc89 (Jun 10, 2022)

Lee Jay said:


> There's really nothing there to hold on to.


So you’ve never used a point and shoot? Or a camera phone? 

Pancakes really aren’t designed for long, demanding photo shoots. They’re supposed to be small.


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## neuroanatomist (Jun 10, 2022)

Lee Jay said:


> Okay, but how do you hold the camera? I usually hold the weight of the camera in my left hand by putting my left hand under the CG of the camera-lens combination, which is always somewhere along the length of the lens. With a small prime, the CG is in the body and there's no place for me to put my left hand. That leads to trying to hold the body with my left hand on the left edge of the body where there's no grip.


Really not sure what the issue is here. You just hold the camera from the bottom. Most cameras have one.

Personally, I use an E1 hand strap on my bodies, and that lets me support the weight on camera + pancake with my right hand. I just need light touch of my left hand for stability.


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## Lee Jay (Jun 10, 2022)

Jasonmc89 said:


> So you’ve never used a point and shoot? Or a camera phone?
> 
> Pancakes really aren’t designed for long, demanding photo shoots. They’re supposed to be small.


Yeah, and they're just as hard to hold. Camera phones are much worse because they're both too small and have no viewfinders.

For me, one of the big attractions of an ILC is that it's just so much easier to hold than a compact or a phone.


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## Lee Jay (Jun 10, 2022)

neuroanatomist said:


> Really not sure what the issue is here. You just hold the camera from the bottom. Most cameras have one.
> 
> Personally, I use an E1 hand strap on my bodies, and that lets me support the weight on camera + pancake with my right hand. I just need light r
> touch of my left hand for stability.


That's just poor technique. Holding under the CG is more stable both because forces don't translate into rotations and because your left arm can be braced against your torso. The right hand should be holding no weight, just operating controls and helping with pointing.


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## entoman (Jun 10, 2022)

Jasonmc89 said:


> You know, you don’t _have_ to use a pancake lens..?
> 
> Slap that massive 50mm 1.2 on it if you want.


What's better, a pancake or a beer barrel? I'll take the beer!


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## Franklyok (Jun 10, 2022)

entoman said:


> What's better, a pancake or a beer barrel? I'll take the beer!


Planty of space for sensor ibis movement… looking forward to 25 stop ibis


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## neuroanatomist (Jun 10, 2022)

Lee Jay said:


> That's just poor technique. Holding under the CG is more stable both because forces don't translate into rotations and because your left arm can be braced against your torso. The right hand should be holding no weight, just operating controls and helping with pointing.


My technique is fine, thanks. I get that you can only handle doing things one way, but that doesn’t mean your way is the only way. Would you have no weight on your right hand when handholding a 1-series body with a 600/4 II lens?

Have you ever used a hand strap on a gripped body? The weight is entirely on the back of your hand, your fingers aren’t supporting anything.

With a pancake lens, the camera body itself is the center of gravity. Put your hand under the camera. This just isn’t that hard.

Sounds like you speak from a lack of experience in this particular area.


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## Dragon (Jun 10, 2022)

entoman said:


> As you point out, the patent application makes no mention of "APS-C" or "RF-S".
> 
> The "specs" are, as you say, an informed guess - by a highly experienced commentator, Keith Cooper of Northlight.
> 
> ...


These lenses are pancakes w/o IS, so more IBIS travel room is needed for good stabilization. With an IS lens, the IBIS needs to do less (if anything all), so the image circle can be smaller.


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## entoman (Jun 10, 2022)

Just as an aside:

Can anyone explain why the angle of view of lenses (in every Canon patent application that I've seen) is given as a "half angle of view"?


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## AJ (Jun 10, 2022)

entoman said:


> The specs state "RF-S" so they must be for APS-C models.
> 
> Maybe a misprint, but perhaps Canon has deliberately elected to have a larger than normal image circle with these wide-angle optics, in order to minimise vignetting and softness in the corners?
> 
> Or am I being daft?



If so, that's opposite to what Canon did with full-frame. RF 16/2.8 and 24-105 kit lens and 24-240 need distortion corrections to be applied to avoid black corners. I would expect Canon would take the same approach with RF-S. As such I don't quite know what to make of these patents.


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## neuroanatomist (Jun 10, 2022)

entoman said:


> Just as an aside:
> 
> Can anyone explain why the angle of view of lenses (in every Canon patent application that I've seen) is given as a "half angle of view"?


The angle given is half of the total angle of view. In other words it’s the angle measured from the edge of the lens to the center/optical axis (as opposed to edge-to-edge, which would be the _full_ angle of view). 

It’s consistent with the value stated for image height, which is the radius (not the diameter) of the image circle.


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## entoman (Jun 10, 2022)

AJ said:


> If so, that's opposite to what Canon did with full-frame. RF 16/2.8 and 24-105 kit lens and 24-240 need distortion corrections to be applied to avoid black corners. I would expect Canon would take the same approach with RF-S. As such I don't quite know what to make of these patents.


Distortion correction seems to be applied to virtually all modern lenses, as it is easier and cheaper to produce a mediocre lens and correct it via firmware trickery, than to produce an optically better lens. But correcting distortion via firmware involves shrinking and/or stretching the edges/corners, which reduces sharpness. So it's better to start with a fairly decent lens design and thus reduce the amount of firmware correction needed.

Similarly you can "correct" vignetting via firmware (or in post), but this involves amplifying the signal in the corners, with a corresponding increase in luminance noise. So again, it's better to produce a lens design that does not have pronounced vigneting in the first place.

As others have pointed out, it would seem that the larger image circle is primarily to enable more efficient IBIS, (as these lenses don't have OIS), but it also should result in sharper corners and less obvious vignetting.


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## entoman (Jun 10, 2022)

neuroanatomist said:


> The angle given is half of the total angle of view. In other words it’s the angle measured from the edge of the lens to the center/optical axis (as opposed to edge-to-edge, which would be the _full_ angle of view).
> 
> It’s consistent with the value stated for image height, which is the radius (not the diameter) of the image circle.


Thanks, I understood what the figures represented, it just struck me as strange that radius and half-angle were adopted as a convention, as opposed to diameter and full angle.


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## Jasonmc89 (Jun 10, 2022)

entoman said:


> What's better, a pancake or a beer barrel? I'll take the beer!


Beer and pancakes..? Sounds like a decent lunch to me!


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## AJ (Jun 11, 2022)

entoman said:


> Distortion correction seems to be applied to virtually all modern lenses, as it is easier and cheaper to produce a mediocre lens and correct it via firmware trickery, than to produce an optically better lens. But correcting distortion via firmware involves shrinking and/or stretching the edges/corners, which reduces sharpness. So it's better to start with a fairly decent lens design and thus reduce the amount of firmware correction needed.
> 
> Similarly you can "correct" vignetting via firmware (or in post), but this involves amplifying the signal in the corners, with a corresponding increase in luminance noise. So again, it's better to produce a lens design that does not have pronounced vigneting in the first place.
> 
> As others have pointed out, it would seem that the larger image circle is primarily to enable more efficient IBIS, (as these lenses don't have OIS), but it also should result in sharper corners and less obvious vignetting.



Or else there is something else going on. Maybe a misprint on the image height, maybe something else. Yes it'd be an advantage with an ibis-equipped body, but it seems silly to me to have a larger image height than needed, especially for wideangle. That would be wasted optics.


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## sanj (Jun 11, 2022)

Expected! Good news.


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## f119a (Jun 11, 2022)

neuroanatomist said:


> That's not APS-C. Closest would be Super35 or (gasp) APS-H.


The third example is the acutal design of RF 16mm f/2.8 STM.
The image height in patent is uncorrected data. And there's 20%+ distortion on all 4 designs - multiply 18.2 by 1.2 you got 21.8, which will cover full frame sensors.


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## f119a (Jun 11, 2022)

unfocused said:


> Don’t get us excited.


These are all Full frame lenses. Image height is low due to their hugh amount of distortion. Just add the 20% distortion back and you get 21.8mm coverage (equiv.)
Even though the RF 16mm is capable of covering the whole sensor at infinity, those extreme corners are stretched and thrown away during correction anyway.


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## f119a (Jun 11, 2022)

Canon Rumors Guy said:


> Continue reading...


There are not APS-C lenses.
Example 3 is the RF 16mm f/2.8 STM available on the street and I don't expect Canon to put the others into production at this time.


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## neuroanatomist (Jun 11, 2022)

f119a said:


> There are not APS-C lenses.
> Example 3 is the RF 16mm f/2.8 STM available on the street and I don't expect Canon to put the others into production at this time.


Compare the lens length in the patent to the current RF 16/2.8, then tell us how the patent example is that lens.


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## jam05 (Jun 11, 2022)

H. Jones said:


> A RF-S 10mm f/2.8 prime would be a super nice budget option for a lot of vloggers/etc. Equivalent to the RF 16mm F/2.8 but an even smaller and more compact option for APS-C. The RF 16mm is already really nice and small for full frame cameras, so I can imagine it would make sense for Canon to fill that role for their crop camera consumers.


16mm f2.8 is rather a slow option for vlogging. Unless one is only producing content in well lit areas or during the middle of the day. Other faster lenses are available


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## juststeve (Jun 11, 2022)

Found looking at the patents interesting for the rather radical shape of the double-sided aspheric element second from the back of the lenses. Some of them have enough fancy curves to resemble the lenses molded for cell phone cameras.


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## f119a (Jun 11, 2022)

neuroanatomist said:


> Compare the lens length in the patent to the current RF 16/2.8, then tell us how the patent example is that lens.


Well tell me why it is not the RF 16mm.
and don't you know it'll pop out a bit at powering on?


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## neuroanatomist (Jun 11, 2022)

f119a said:


> Well tell me why it is not the RF 16mm.
> and don't you know it'll pop out a bit at powering on?
> 
> View attachment 204173


My mistake, you're absolutely correct.

Well, sort of Canon's mistake but I should have looked more carefully at the specifications. The Canon USA page reports the dimensions as
*Maximum Outer Diameter x Length *Approx. 1.6 in. x 2.7 in. (40.1 x ø69.2mm); diameter is listed first in the header, but second in the actual measurements. B&H (where I think I looked for the specs) leaves out that rather important slashed-O next to the 69.2mm value that indicates diameter, and therefore reversed the measurements completely:




Had I thought about it, I'd have realized the diameter of the lens cannot possibly be 40mm, since the throat diameter of the RF mount is 54mm.

Thinking the length of the RF 16/2.8 lens was 69mm based on B&H, with the patent length 63mm but subtracting the flange distance yielding a lens of ~43mm, is what led to my questioning. 

The optical formula length in the patent is consistent with the existing RF lens.

Good catch on your part, these 'new APS-C pancake lenses'...aren't.


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## juststeve (Jun 12, 2022)

I wonder if Canon will change the software-firmware corrections for these lenses depending on format, full frame or APS-C.


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## Bob Howland (Jun 12, 2022)

juststeve said:


> I wonder if Canon will change the software-firmware corrections for these lenses depending on format, full frame or APS-C.


Wild guess: They've all ready done that, a long time ago.


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## Sharlin (Jun 12, 2022)

entoman said:


> Thanks, I understood what the figures represented, it just struck me as strange that radius and half-angle were adopted as a convention, as opposed to diameter and full angle.


It makes sense from the optical design/ray diagram point of view. Distance and angle from the optical axis are what matters mathematically and physically. Indeed in a ray diagram you can just ignore rays that originate below the optical axis without loss of generality, thanks to symmetry. Full angle only matters to the end users, and patent documents are not written for the end users.


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## John Wilde (Jun 12, 2022)

This post made me hungry, so I made homemade buttermilk pancakes.


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## neuroanatomist (Jun 12, 2022)

John Wilde said:


> This post made me hungry, so I made homemade buttermilk pancakes.


Good choice, since it seems like those are the only pancakes you’re getting for now.


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## Skux (Jun 12, 2022)

Lee Jay said:


> "Unsurprisingly" a pancake lens? I find that, generally, the smaller the lens the hard the camera is to handle. Pancake primes are the worst as there's literally nothing to hold onto with your left hand. Why do people want these things? I thought it was only about price, not desirability.


Pancakes are great precisely because you don't need to use your other hand.


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## adrian_bacon (Jun 12, 2022)

neuroanatomist said:


> That's not APS-C. Closest would be Super35 or (gasp) APS-H.


It might have a slightly larger image circle to account for the sensor moving around with IBIS.


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## neuroanatomist (Jun 13, 2022)

adrian_bacon said:


> It might have a slightly larger image circle to account for the sensor moving around with IBIS.


I think that’s been settled. The 16/2.8 in this patent is the existing RF 16/2.8. These aren’t APS-C lenses. 

Canon frequently patents a family and produces one (if any), so we may not ever see any of these designs as products other currently-available RF 16/2.8.


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## AJ (Jun 13, 2022)

I wonder when we're going to hear more about the rumored RF 24/1.8. Will it have a similar optical design?


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## adrian_bacon (Jun 13, 2022)

neuroanatomist said:


> I think that’s been settled. The 16/2.8 in this patent is the existing RF 16/2.8. These aren’t APS-C lenses.
> 
> Canon frequently patents a family and produces one (if any), so we may not ever see any of these designs as products other currently-available RF 16/2.8.


I made the mistake of responding before reading the whole thread.


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## tapanit (Jun 13, 2022)

Lee Jay said:


> Okay, but how do you hold the camera? I usually hold the weight of the camera in my left hand by putting my left hand under the CG of the camera-lens combination, which is always somewhere along the length of the lens. With a small prime, the CG is in the body and there's no place for me to put my left hand. That leads to trying to hold the body with my left hand on the left edge of the body where there's no grip.


Consider getting an L-bracket. One that allows the side part to be extended as needed.


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## entoman (Jun 13, 2022)

tapanit said:


> Consider getting an L-bracket. One that allows the side part to be extended as needed.


An interesting solution to the OPs "problem". Is it really *that* difficult to hold a camera with a pancake steady? 

Seems obvious too, but I'll pooint it out nevertheless, that much of the *appeal* of a pancake on a body like an R10 or R7 is the compactness.
And adding an L-bracket makes it, er, bigger!


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## David - Sydney (Jun 14, 2022)

Given that the existence of RF-S lenses was only confirmed recently, I am surprised at CRguy's assertion that
"One of the most requested RF-S lenses is unsurprisingly a pancake lens"

I would have thought that one of the most requested RF lenses that hasn't been released would have been a cheap/wide pancake similar to the EF40mm but alas, it isn't on the roadmap.

Adapting the EF version doubles the weight/length/cost and a new RF version shouldn't be a difficult to implement. Not a high margin product but would make its way into many people's kits.


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## tapanit (Jun 14, 2022)

entoman said:


> An interesting solution to the OPs "problem". Is it really *that* difficult to hold a camera with a pancake steady?
> 
> Seems obvious too, but I'll pooint it out nevertheless, that much of the *appeal* of a pancake on a body like an R10 or R7 is the compactness.
> And adding an L-bracket makes it, er, bigger!


Well, I have L-brackets in all my bodies anyway, and ones that allow extending the side part are neither bigger (when not extended) nor heavier than ones that don't. And sometimes it is convenient to be able to hold the camera with left hand, too, even though I don't have such problems with pancakes as the OP does.


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## Lee Jay (Jun 15, 2022)

tapanit said:


> Consider getting an L-bracket. One that allows the side part to be extended as needed.


I just use lenses that are big enough to hold, and there's no issue.


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## neuroanatomist (Jun 15, 2022)

Lee Jay said:


> I just use lenses that are big enough to hold, and there's no issue.


I just know how to hold a camera with any lens attached to it, whether that lens is a pancake or a supertele, and there's no issue.


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