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



## Canon Rumors Guy (Jan 11, 2018)

```
<strong>Update:</strong> <a href="https://www.canonnews.com/canon-applies-for-a-fisheye-lens-one-possible-mirrorless-prime-patent">Canon News has dug a bit further</a> and come to the conclusion that these optical formulas are for a fisheye due to the lenses having a 175 degree field of view.</p>
<p>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.</p>


<p><strong>Japan Patent Application <a href="https://www.canonnews.com/canon-applies-for-a-uwa-lens-one-possible-mirrorless-uwa-prime-patent">2018-004726</a></strong></p>
<p>Canon EF-M 9.5mm f/4</p>
<ul>
<li>Focal distance 9.50</li>
<li>F number 4.10</li>
<li>Imaging field angle (degree) 175</li>
<li>Image height 13.66</li>
<li>Whole length of the lens 63.97</li>
<li>BF 23.16</li>
</ul>
<p>Canon EF 15mm f/4</p>
<ul>
<li>Focal distance 15.18</li>
<li>F number 4.12</li>
<li>Imaging field angle (degree) 175</li>
<li>Image height 21.64</li>
<li>Whole length of the lens 130.16</li>
<li>BF 58.19</li>
</ul>
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## ahsanford (Jan 11, 2018)

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

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


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## wsmith96 (Jan 11, 2018)

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

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


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## ahsanford (Jan 11, 2018)

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



wsmith96 said:


> 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


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## rrcphoto (Jan 11, 2018)

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



ahsanford said:


> 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.


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## ahsanford (Jan 11, 2018)

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



rrcphoto said:


> ahsanford said:
> 
> 
> > Wince on the f/4.
> ...



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


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## rrcphoto (Jan 11, 2018)

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



ahsanford said:


> rrcphoto said:
> 
> 
> > ahsanford said:
> ...



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?


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## ad (Jan 11, 2018)

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

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


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## wsmith96 (Jan 11, 2018)

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



ahsanford said:


> wsmith96 said:
> 
> 
> > I would have expected them to be 2.8's at least. Perhaps this is a defensive patent.
> ...



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.


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## rrcphoto (Jan 11, 2018)

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



ad said:


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



nice catch!


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## ad (Jan 11, 2018)

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



rrcphoto said:


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


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.


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## Antono Refa (Jan 12, 2018)

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?


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## neuroanatomist (Jan 12, 2018)

Antono Refa said:


> 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.


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## dcm (Jan 13, 2018)

neuroanatomist said:


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



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.


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## brad-man (Jan 13, 2018)

dcm said:


> neuroanatomist said:
> 
> 
> > Antono Refa said:
> ...



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...


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## mariuspavel (Jan 27, 2018)

Ef 15mm f/4 will be a good lens for DSLR video, if the rumos is true. Now i use Samyang 14mm, witch is a bit nah... blurry in the corners.


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