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

[neuroanatomist]

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.

 

[jam05]

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

 

[juststeve]

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.

 

[f119a]

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?

 

[neuroanatomist]

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.

 

[juststeve]

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

 

[Bob Howland]

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.

 

[Sharlin]

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.

 

[John Wilde]

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

 

[neuroanatomist]

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.

 

[Skux]

"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.

 

[adrian_bacon]

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.

 

[neuroanatomist]

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.

 

[AJ]

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

 

[adrian_bacon]

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.

 

[tapanit]

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.

 

[entoman]

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!

 

[David - Sydney]

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.

 

[tapanit]

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.

 

[Lee Jay]

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.