Updated: Patent: EF 15mm f/4 & EF-M 9.5mm f/4

[Canon Rumors]

Update: Canon News has dug a bit further and come to the conclusion that these optical formulas are for a fisheye due to the lenses having a 175 degree field of view.

A new patent showing an optical formula for a new wide angle prime has appeared. The full frame lens in the application is an EF 15mm f/4, while the APS-C optical formula of a EF-M 9.5mm f/4 shows a shorter backfocus than an EF-S lens and could actually be EF-M.

Japan Patent Application 2018-004726

Canon EF-M 9.5mm f/4

• Focal distance 9.50
• F number 4.10
• Imaging field angle (degree) 175
• Image height 13.66
• Whole length of the lens 63.97
• BF 23.16

Canon EF 15mm f/4

• Focal distance 15.18
• F number 4.12
• Imaging field angle (degree) 175
• Image height 21.64
• Whole length of the lens 130.16
• BF 58.19

[ahsanford]

Wince on the f/4.  When I think of an f/4 prime, I think:

• A really long lens that would be problematic, massive or really expensive at f/2.8
  
  
• A specialty tool like T/S

...and we already have an EF-M 11-22 which is already f/4 on the 11mm end and an EF-S 10-22 f/3.5-4.5 which would actually be quicker than this new prime.  I appreciate this is more like FF 14 prime than the wide end of a 16-35 zoom, but shouldn't primes be quicker than this?

(Am I missing something?  Is this a pancake or super tiny lens?  What other virtues might it have that might warrant making a product out of it?)

- A

[wsmith96]

I would have expected them to be 2.8's at least.  Perhaps this is a defensive patent.

[ahsanford]

I would have expected them to be 2.8's at least.  Perhaps this is a defensive patent.

...or this is actually a cool / useful / small wide prime for FF (like the non-L 24/28/35 lenses) and they just decided to knock out a crop equivalent while they were there?

- A

[rrcphoto]

Wince on the f/4.

not sure why. the applications that need faster than f/4 on a 15mm are pretty rare.

the 17/3.5 used to be a hugely popular UWA.

the Zeiss 18/3.5 was a pretty darn good lens as well.

the zeiss 15/2.8 is freaking huge.

[ahsanford]

Wince on the f/4.

not sure why. the applications that need faster than f/4 on a 15mm are pretty rare.

I just think primes should offer more sharpness / more speed / smaller size than zooms, and if they don't, why sell it?

As for applications, astro immediately comes to mind.

- A

[rrcphoto]

Wince on the f/4.

not sure why. the applications that need faster than f/4 on a 15mm are pretty rare.

I just think primes should offer more sharpness / more speed / smaller size than zooms, and if they don't, why sell it?

As for applications, astro immediately comes to mind.

- A

astro is a pretty rare application for a UWA, not all lenses has to cater to a niche.

just how many canon less than 16mm lenses exist?

2?

[ad]

175 degrees imaging field angle pretty much means these are fisheye lenses, no? Comparing them to rectilinear lenses isn't that useful.

[wsmith96]

I would have expected them to be 2.8's at least.  Perhaps this is a defensive patent.

...or this is actually a cool / useful / small wide prime for FF (like the non-L 24/28/35 lenses) and they just decided to knock out a crop equivalent while they were there?

- A

True, that may be the case.  There is a lot of activity in the EF-M line of lenses lately.  Maybe canon is working towards parity between the EF-M and EF line of lenses from a FOV perspective.  Daylight/tripod shooters most likely won't have an issue with the EF f/4, especially if it leads towards a lighter kit.

[rrcphoto]

175 degrees imaging field angle pretty much means these are fisheye lenses, no? Comparing them to rectilinear lenses isn't that useful.

nice catch!

[ad]

175 degrees imaging field angle pretty much means these are fisheye lenses, no? Comparing them to rectilinear lenses isn't that useful.

nice catch!

Something is still rather odd, though. In another current post Canon News lists a field angle of 14.61 degrees for the 85mm lens and 12.57 degrees for the 100mm lens. That is about right for the _half_ viewing angle of a rectilinear full-frame lens (analogous to image height being half the diagonal or the radius of the image circle). Even for a fisheye the same interpretation doesn't work here...

Edit: I managed to look at the auto-translated patent and several figures show 87.5 degrees for a half field, corresponding to 175 degrees for a full field. So the notation just seems to be inconsistent with the other listing.

[Antono Refa]

Canon stopped making the EF 15mm f/2.8 fisheye when the EF 8-15mm f/4L fisheye zoom came out.

Why bother make f/4 fisheye lenses now?

[neuroanatomist]

Canon stopped making the EF 15mm f/2.8 fisheye when the EF 8-15mm f/4L fisheye zoom came out.

Why bother make f/4 fisheye lenses now?

An EF-M fisheye would make sense...probably not many people buying L-series lenses for primary use on M-series bodies.  I doubt we'll see a 15mm f/4 fisheye for the EF mount.

[dcm]

Canon stopped making the EF 15mm f/2.8 fisheye when the EF 8-15mm f/4L fisheye zoom came out.

Why bother make f/4 fisheye lenses now?

An EF-M fisheye would make sense...probably not many people buying L-series lenses for primary use on M-series bodies.  I doubt we'll see a 15mm f/4 fisheye for the EF mount.

Agreed.   Tried the EF 8-15 L on my Ms, but ended up getting the Samyang 8mm f/2.8 which has been fine.  Don’t use it all that much, but that is the nature of fisheyes.  It’s way down the list of EF-M primes that might interest me.

[brad-man]

Canon stopped making the EF 15mm f/2.8 fisheye when the EF 8-15mm f/4L fisheye zoom came out.

Why bother make f/4 fisheye lenses now?

An EF-M fisheye would make sense...probably not many people buying L-series lenses for primary use on M-series bodies.  I doubt we'll see a 15mm f/4 fisheye for the EF mount.

Agreed.   Tried the EF 8-15 L on my Ms, but ended up getting the Samyang 8mm f/2.8 which has been fine.  Don’t use it all that much, but that is the nature of fisheyes.  It’s way down the list of EF-M primes that might interest me.

You can say that again! First a macro that's too slow and too wide for anyone other than foodies, and now possibly a fisheye? I find it hard to believe that there isn't a market for enthusiast class M lenses, but apparently Sigma agrees with them. It seems that Rokinon is the best candidate for some M primes. Nice to see them developing a line with AF...