# Patent: Canon EF-M 55mm f/3.5 Macro



## Canon Rumors Guy (Dec 21, 2015)

```
A macro lens was to be a part of the EOS M’s future, and we now see what I think is our first patent for an EF-M macro lens. This optical formula is for an EF-M 55mm f/3.5 Macro for an APS-C sensor.</p>
<p>Patent Publication No. 2015-215391 (Google Translated)</p>
<ul>
<li>Published 2015.12.3</li>
<li>Filing date 2014.5.8</li>
<li>Focal length 53.73</li>
<li>F-number 3.50</li>
<li>Half angle (in degrees) 14.26</li>
<li>Image height 13.66</li>
<li>Overall length of the lens 76.39</li>
<li>BF 17.69</li>
</ul>
<p>While a full frame mirrorless solution from Canon appears to be in the works, we haven’t heard anything about what kind of mount the camera would have.</p>
<p>We are expecting some EOS M announcements in the first quarter of 2016.</p>
```


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## Chaitanya (Dec 21, 2015)

eagerly waiting for this lens.


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## neuroanatomist (Dec 21, 2015)

Interesting, and a decent addition to the lineup. 

Would have preferred an f/2.8 lens which would have been better for portrait use, though...


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## Lee Jay (Dec 21, 2015)

Well, that seems rather pointless. Just use the EF-s 60mm macro. This one shouldn't be a whole lot smaller since it's longer than 44mm. Maybe a bit because it's slightly slower and slightly shorter in focal length.


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## neuroanatomist (Dec 21, 2015)

Lee Jay said:


> This one shouldn't be a whole lot smaller since it's longer than 44mm.



The patent indicates the lens would likely be a bit under 2.5" long. The EF-S 60mm plus the EF Mount Adapter would be about 4" long – 60% longer than the EF-M macro lens. That's pretty significant, IMO.


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## HaroldC3 (Dec 21, 2015)

Also would have preferred 2.8 and IS but I guess then it would have cost quite a bit.


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## Wizardly (Dec 21, 2015)

Example 1: solved for APS-C sensor

FL: 53.73mm
F no.: 3.5
Half field angle: 14.26º
Image Height 13.66 mm
Lens length: 76.39 mm
BF: 17.69 (possibly works for EF-M, protrudes into the body?)

Example 2: solved for APS-C
FL: 46.39 mm
F no: 3.5
Half field angle: 16.41º
Image height: 13.66 mm
Lens length: 75.34 mm
BF 16.08 (too close for EF-M, protrudes into the body")

Example 3: Solved for APS-C
FL: 58 mm
F no: 2.92
Half field angle: 13.22º
Image Height: 13.63 mm
Lens Length: 107.54 mm
BF: 34.5 mm (too close for EF, very far for EF-M)

Working Example 1: this is the flange distance for Fuji X-mount.

Example 3 is the most interesting to me. ~60mm f/2.8 macro for EF-M


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## weixing (Dec 21, 2015)

Hi,
Another EF-M lens? Hmm... Look like canon getting more serious in mirrorless market and may be a more serious M is coming...

Have a nice day.


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## TWI by Dustin Abbott (Dec 21, 2015)

Something like this would be very interesting, particularly if they could bring it at a price point of around $299 US. Nice to see some hints of development going on at Canon. I do think the M system is worth investing in, even if they haven't gotten it together quite yet.


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## neuroanatomist (Dec 21, 2015)

Wizardly said:


> Example 1: solved for APS-C sensor
> 
> FL: 53.73mm
> F no.: 3.5
> ...



There have been other EF-M patents with backfocus distances as short as 15.81 mm.


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## Khufu (Dec 21, 2015)

Does this lens not project an image smaller than Canon's APS-C sensor, which is smaller than everyone else's APS-C sensor?..

*Edit* along with the other two examples highlighted by Wizardly...


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## neuroanatomist (Dec 21, 2015)

Khufu said:


> Does this lens not project an image smaller than Canon's APS-C sensor, which is smaller than everyone else's APS-C sensor?..
> 
> *Edit* along with the other two examples highlighted by Wizardly...



The normal image height for a Canon APS-C image circle is 13.66mm. 'Image height' is actually the radius of the image circle, slightly more than half the diagonal measure of the sensor. For a FF sensor, the image height in a lens patent is generally 21.65mm.


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## Khufu (Dec 21, 2015)

Well of cooourse that's what "Image Height" means, how silly of me to assume it referred to the height of the image 
Thanks for clarifying, Neuro! Any idea, er, why... why this measurement which is smaller than the height, nevermind the width, of the recorded image is used? As someone whom this is a new concept to: it's kinda' ridiculous


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## neuroanatomist (Dec 21, 2015)

Khufu said:


> Well of cooourse that's what "Image Height" means, how silly of me to assume it referred to the height of the image
> Thanks for clarifying, Neuro! Any idea, er, why... why this measurement which is smaller than the height, nevermind the width, of the recorded image is used? As someone whom this is a new concept to: it's kinda' ridiculous



Because lens elements are circular, it makes sense to use the radius of the circle as a specification, rather than some arbitrary chord. What if the lens was intended for a sensor with a 4:3 or a 16:9 aspect ratio (compact, m4/3, video, etc.) instead of the 3:2 ratio used in most dSLRs? That would render the image height impossible to translate into a meaningful number without also specifying the sensor format. Thus, specifying a measurement that's unambiguous is quite logical. 

Pie are round, cornbread are square.


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## Khufu (Dec 21, 2015)

I'll admit that there's logic there, Neuro, but who's the idiot who decided that "Image Height" was an appropriate name for it? It seems as logical as taking and misapplying to this attribute any other term, like Depth of Field, Flavour of Pie or Image Height... oh, wait, that's what they went with 

I'm aware that projected image circles aren't necessarily usable and go wildly distorted at the edges, geometrically and otherwise, so is the "image height" in this context relative to the circle that a manufacturer is proud to consider "usable", or the circle of projected light in its entirety, fuzz-and-all? If the former, yeah, I can get on board with this being a worthwhile measured attribute, " Radius of Image Circle ", alas Image Height just isn't going to sit well with me, just like 1" Sensor


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## neuroanatomist (Dec 21, 2015)

Khufu said:


> I'll admit that there's logic there, Neuro, but who's the idiot who decided that "Image Height" was an appropriate name for it? It seems as logical as taking and misapplying to this attribute any other term, like Depth of Field, Flavour of Pie or Image Height... oh, wait, that's what they went with
> 
> I'm aware that projected image circles aren't necessarily usable and go wildly distorted at the edges, geometrically and otherwise, so is the "image height" in this context relative to the circle that a manufacturer is proud to consider "usable", or the circle of projected light in its entirety, fuzz-and-all? If the former, yeah, I can get on board with this being a worthwhile measured attribute, " Radius of Image Circle ", alas Image Height just isn't going to sit well with me, just like 1" Sensor



The 'idiot' was probably some optical physicist lost in the depths of time. Remember those 'thin lens approximation' ray diagrams? It's image height as in the largest value of *hi* (height of image, image height) that can be projected onto the image plane. In patent terminology for a lens intended for an APS-C sensor, it's stated as, "The optical system of this embodiment has a maximum image height of 13.66 mm."


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## brad-man (Dec 21, 2015)

neuroanatomist said:


> Interesting, and a decent addition to the lineup.
> 
> Would have preferred an f/2.8 lens which would have been better for portrait use, though...



Amen.




Lee Jay said:


> Well, that seems rather pointless. Just use the EF-s 60mm macro. This one shouldn't be a whole lot smaller since it's longer than 44mm. Maybe a bit because it's slightly slower and slightly shorter in focal length.



Some of us only have the EF100L macro, and that would be too large.




TWI by Dustin Abbott said:


> Something like this would be very interesting, particularly if they could bring it at a price point of around $299 US. Nice to see some hints of development going on at Canon. I do think the M system is worth investing in, even if they haven't gotten it together quite yet.



I agree to the point of having already purchased all of the M lenses (except the latest M10 kit zoom). I expect (hope) the next iteration will be for enthusiasts with truly fast AF. And I really really hope that the M mount is suitable for FF when Canon releases it in the 20s


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## AvTvM (Dec 22, 2015)

*Re: Patent: Canon EF-M 55mm f/3.5 Macro / not interested*

Dont want a Macro lens, for rare use i take my EF-S 60/2.8. will definitely not buy a slow 55mm prime. Got the 55-200 also, so 55mm @ f/4.5 is already covered - with IS. 

If Canon wants my money, its got to be a very compact, moderately fast EF-M tele with IS - e.g. an EF-M 85/2.4 IS STM for portraits and concerts and general walkabout use.


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## grainier (Dec 22, 2015)

Jeez, Canon, just take the old 50/3.5 FD and stick a motor on it.


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## Vivid Color (Dec 22, 2015)

neuroanatomist said:


> Interesting, and a decent addition to the lineup.
> 
> Would have preferred an f/2.8 lens which would have been better for portrait use, though...



I agree, an f/2.8 lens would've been better. I also would've preferred a slightly longer focal length.


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## Wizardly (Dec 22, 2015)

English USPTO patent application:	US20150323764 A1

In comparing example 3 to JP,2006-153942 (I believe this is the patent that embodied by the existing EF-S 60mm f2.8 Macro), it seems quite possible that this is going to be the EF-S 60mm f/2.8 Macro II, or the EF-M 60mm f/2.8 Macro.

Comparing the distortion graphs, example 3 compares quite well to 2006-153942.


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