# First Canon Mirrorless Related Patent?



## Canon Rumors Guy (Mar 18, 2011)

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<p><strong>The First Canon Mirrorless Related Patent?

</strong>This appears to be a lens adaptor. EF to something else?</p>
<p>Egami compares it to the Sony NEX to alpha mount adaptor.</p>
<p><strong>Publication number:</strong> Patent 2011-53437 (P2011-53437A)

<strong>Release date</strong>: March 17, 2011 (2011.3.17)

<strong>Title of invention:</strong> Lens adapter apparatus and system</p>
<p><strong><a href="http://translate.google.com/translate?js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&sl=ja&tl=en&u=http%3A%2F%2Fegami.blog.so-net.ne.jp%2F2011-03-18%23more" target="_blank">Google Translated Link</a> (egami)</strong></p>
<p><strong>CR’s Take

</strong>I don’t read japanese, so I’m relying on the job the translator does to the site. It looks like a lens mount adaptor. If/when Canon enters the mirrorless market, I am pretty confident they will have an EF adaptor for such a system.</p>
<p>This is the first patent I’ve seen that has even a remote chance of being about a mirrorless camera from Canon.</p>
<p><strong><span style="color: #ff0000;">c</span>r</strong></p>
<p><strong> </strong></p>
```


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## CdnBook (Mar 18, 2011)

Perhaps it's a PL mount adapter for cinema lenses?


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## J-Man (Mar 18, 2011)

Not even close to PL mount, PL mount has 4 lugs on the bayonet where Canon has 3, also PL mount has no electronic communication.

I scaled the image size to match with the EF mount, it appears the registration distance for this EVIL camera is close to 30mm, which puts it just slightly deeper than Contax G1, so no Leica M & Screw mount lenses.
http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html

Also the throat dia. looks too small for FF, APS-H is almost the same size, so is too close to call, looks like it might be APS-C.  I hope there is some wiggle room for sensor size. (I have not ray traced any camera lenses so I'm not sure if there will be any vignetting with larger than APS-C sensors.)


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## able (Mar 18, 2011)

CR... I think you need to show the second image. The first image shows how the adapter design was engineered by competitors and the second image shows the Canon design with the contacts rotated. The Canon design is apparently simpler to fabricate resulting in lower manufacturing cost. 

Since one competitor already manufactures a Canon version of the mount, this adapter most likely solves an existing problem.


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## J-Man (Mar 18, 2011)

Looks to me like they are just comparing 4/3 to m4/3, Alpha to E mount, and EF to Canon's new mount.
the 2 diagrams show two locations for the communication connections, the first, similar to Sony's patent and the 2nd which is different than Sony's and therefor not a patent infringement.


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## coldstone (Mar 18, 2011)

sigma shares the same protocol with canon
only the contact block looks a bit different 
i saw custom made blocks to fit canon lenses on sigma cameras for infrared images
maybe the adapter is for sigma


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## kubelik (Mar 18, 2011)

I don't see a reason for making an adaptor for sigma lenses as sigma makes lenses specifically for EF mount already. I agree with CR that this is the first hint of Canon starting to think about developing a mirrorless camera system.

I'm not one of those people dying to get my hands on a mirrorless as I enjoy having a large viewfinder and having a body that balances well with large lenses, but I sure wouldn't mind an EF-variant mirrorless camera that I can stick some existing lenses on, to bring as a backup or to bring to places that my 5DII sticks out like a sore thumb in


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## transpo1 (Mar 18, 2011)

Could be an adapter for a an APS-C camcorder...


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## x-vision (Mar 18, 2011)

CdnBook said:


> Perhaps it's a PL mount adapter for cinema lenses?



That's what I'm thinking too. 
Or maybe an adapter to mount EF lenses on video cameras.


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## Grendel (Mar 18, 2011)

Hm, eyeballing the thickness of the adapter in the drawing -- could be EF-to-FT. Too thin for something w/ a flange-back distance of MFT IMHO.


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## dougkerr (Mar 18, 2011)

The corresponding US patent application is 2011/0052185.

If we took the figure in the patent to be realistic and to scale, it would suggest that the "new" body had a back flange of about 29.8 mm. (The scale flange-to-flange thickness of the adapter seems to be about 14.2 mm; the back flange of the EF/EOS mount is 44.0 mm.)

The information I have is that the back flange for the Four Thirds format is 38.67 mm; for the Micro Four Thirds, 20.00 mm.

I have not seen a back flange speculated for the rumored Canon "EVIL" body.

There have been many recent Canon patents that suggest applicability to a mirrorless interchangeable lens camera (mostly in the area of AF technique).

Best regards,

Doug


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## Jonathan (Mar 18, 2011)

Hello guys !

@Dougkerr : 
At the first glance your calculation is right, i've found the same result of 14.2mm when i did ot the first time too. 
I've redone the calculation a second time (after the measuring the distance between the mount and the mirror in upper position on my rebel) and i've found 12.8mm (which approximately matches the adapter lenght and the spacing between mount and mirror in a rebel). 

If this patent really exists and if canon released such a thing with a new mount, it will be very exciting !

It means that they will split the EF/EF-s systems into two distinctive systems ensuring in the same time a full retrocompatibility from up to bottom.

IMHO, what i've red about future canon decisions, they won't make MIRRORLESS, and for me that's a good thing.
Nonetheless, they claim their will to make a decent compact dslr alternative for canon user's with a mirror ! 
They know that most of their users do not want to get a rid of an OVF. 

What we could see and "extract" from the patent diagram:
- The new mount's throat is slightly smaller.
- It's a 12.8mm adapter that will accept actual EF-S Lenses. => The new system will keep the actual APS-C (1.6x crop factor) sensors.
- The pin connectors on the newer mount side are the same as EF's ones, they just added 3 extra pins, so the communication protocal would be same as EF. 

(olympus did the same when they created micro four third from original four third mount, in order to add a high speed communication port between body&lenses for video functions. Even Sony did exactly the same Alpha/Nex. ) 

- The pin connectors are located on the right side of the camera and vertically mounted. ???

=> Can we imagine a body with vertically mounted sensor ?? Why not, Olympus have already done this with the original compact half frame Pen FT and it got a fixed pellix mirror. Canon have experience with pellix, just see the EOS RT. 
Canon could even make a camera with a slapping pellix mirror for a liveview mode with better IQ if the optical finder isn't needed. ;D

- The new mount will have a 12.8mm shorter register than EF. => ~31.2mm register. That's enough to keep the APS-C mirror box in a tight fit.

- A shorter flange back have two main advantages for optical engineers 8): 
*It's easier to make wide angle lenses more compact with less vignetting and aberrations and even brighter 
(ex: leica M lenses ) 
*A complete compact prime lenses offering (APS-C image circle) would make more sense for a smaller mount.
They gain 12.8mm whereas a compact prime could only measure 20mm in lenght (example: sony E 16mm 2.8 or voigtlander 20mm & 40mm SLII pancake).

As a conclusion, the new system would be a sort of "shaved" or "receded " EF-S mount but still with a mirror box.
I wonder how will they name this new sytem, EF-SS (EF-Small Shorter) ? EF-S minus? EF-S Evolution ? EF-S v2.0 ?

Plus we can imagine the dimension of the new body, it's quite obvious:

*Grab an EOS Rebel/Kiss/XXXD and put off the 12.8mm on the mount.
*Put-off the pop-up flash above the pentamirror and replace it by a built-in tilt-up flash located on the left of the body.
*Remove the protuding grip for the right hand.
*Put SD or even micro SD card and a smaller battery.
*Mount a bright compact prime ( 30mm f/1.8 ) or a "pancake" lens.
=> You obtain a compact APS-C sized sensor DSLR with an OVF with the dimension of an Olympus EPL2 and its 20mm 1.7 pana prime ! :

**Create an optional battery-grip if needed to obtain a pro dslr in reduction . :

PS: I apologize for my scholar english, english is not my first language.


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## DuLt (Mar 19, 2011)

Couldn't they be ditching the EF-S system in order to make a new mount with a shorter flage focal distance?

So they would have EF system and a new EF-SS (super short flage focal distance) system with smaller lenses that would fully accept EF and EF-S lenses?

This way they would increase the distance between amateur and pro ranges.


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## Jonathan (Mar 19, 2011)

Yes, "they would have EF system and a new EF-SS (super short flage focal distance) system with smaller lenses that would fully accept EF and EF-S lenses." That's right.

But i don't agree, they would not increase the distance between amateur and pro range.
They would provided a full interoperability and full retrocompatibilty even with old FD lens with another adapter (with the APS-C 1.6x crop factor) . 

Plus; by adding a complete compact prime range, they would fill the gap for the ef-S lenses user.
There is a lack of prime lenses for EF-S. (EF-S = APS-C lenses such as the 60mm 2.8 macro) 

I think, they plan to make all EF DSLR Full Frame or at least with APS-H sensor.

So that, EF-S lenses user will have to move into the new mount, and they'll gain compactness without decreasing quality and performance.
EF 24x36 lenses user will keep the existing mount and would benefit from democratized full frame sensor in the EF dslr range.


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## DuLt (Mar 19, 2011)

I see. basically making a new, backward's compatible, full frame mount.


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## Jonathan (Mar 19, 2011)

If you have seen the diagram you would immediately understand that the new mount can only support APS-C format sensor.


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## dougkerr (Mar 19, 2011)

Hi, Jonathan,



Jonathan said:


> Hello guys !
> 
> @Dougkerr :
> At the first glance your calculation is right, i've found the same result of 14.2mm when i did ot the first time too.
> I've redone the calculation a second time (after the measuring the distance between the mount and the mirror in upper position on my rebel) and i've found 12.8mm (which approximately matches the adapter lenght and the spacing between mount and mirror in a rebel).


I'm not sure I follow. Are you trying to determine the flange back distance of an EOS body? That is known to be 44.00 mm.

Or were you trying to determine the thickness of the adapter from the patent drawing? I scaled it from the inside diameter of the flange ring on the front of the adapter, assuming it to be the same as the corresponding distance on an EOS mount (which is 54.0 mm).

That gives me a flange-face-to-flange-face thickness for the adapter of approximately 14.2 mm. 




> - The pin connectors on the newer mount side are the same as EF's ones, they just added 3 extra pins, so the communication protocal would be same as EF.



The patent says that when using the "new" lenses" the protocol would be a new one, but when an EF lens was attached through a (passive) adapter, the body would use the EF protocol. 



> - The pin connectors are located on the right side of the camera and vertically mounted. ???



The (entire) point of the patent is that if the contact block on the new body were put at 6 o'clock, things in that area of the adapter would be very congested, so it would be desirable on the new body to have the contacts either at 12 o'clock or at 9' o'clock (as would be seen looking at the face of the camera). Both these situations are shown in figures in the patent.



> - The new mount will have a 12.8mm shorter register than EF.


Not by my reckoning. How did you get that value?



> PS: I apologize for my scholar english, english is not my first language.



Your English is fine!

Best regards,

Doug


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## dougkerr (Mar 19, 2011)

Hi, Jonathan,



Jonathan said:


> If you have seen the diagram you would immediately understand that the new mount can only support APS-C format sensor.



The rumor is that the new body series will have an 18 x 12 mm sensor. I see nothing in the patent that would conflict with that.

Just a rumor, of course.

Best regards,

Doug


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## Jonathan (Mar 19, 2011)

Hi dougkerr,

The first time i've done the measurement between 33a and 31a, and i've found 14.2mm like you.
But if you look closely to the diagram, i suppose it will create a tiny gap of a few millimeters. 
So i redone the calculation, suposing the adapter would "embrace" the new mount "gapless". It gives approximately 12.8~13mm 

Quote

- The pin connectors on the newer mount side are the same as EF's ones, they just added 3 extra pins, so the communication protocal would be same as EF. 

I suppose they would "mimick" what olympus did with their "passive" 4/3 to micro4/3 adapter.

Best regards,

Jonathan


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## dougkerr (Mar 19, 2011)

Hi, Jonathan,



Jonathan said:


> The first time i've done the measurement between 33a and 31a, and i've found 14.2mm like you.
> But if you look closely to the diagram, i suppose it will create a tiny gap of a few millimeters.



I'm not sure what you mean.

In any case, the back face of the EF lens would contact surface 33a, and face 31a would contact the face of the "new body" mount (the face that, on an actual EOS mount, corresponds to surface 33a of the adapter).

Note that in the rear view that ring 31 has two contacting ribs on its outer and inner edges, exactly as we see on the rear of an EF lens (they touch surface 33a). 

The four screws seen on the rear view are "between" those ribs, actually invading them a little. It is just like that on the rear of an EF lens (at a slightly larger diameter, of course).



> So i redone the calculation, suposing the adapter would "embrace" the new mount "gapless". It gives approximately 12.8~13mm



I don't follow your vision of the coupling. As I said above, as I see it, the back face of the EF lens would contact surface 33a, and face 31a would contact the face of the "new body" mount (the face that, on an actual EOS mount, corresponds to surface 33a of the adapter).

Do you not agree that the distance from surface 33a to surface 31a appears to be about 14.2 mm? 

At the arbitrary scale at which I worked, the distance across the inner diameter of the front flange of the adapter (the circle that lies just inside the heads of the four cross-head screws) measured 1.981". I have no reason to believe that this face is any different than the mount on my EOS 40D (it looks exactly like the picture). There, that actual diameter is 54.0 mm.

In my workspace, the distance between surfaces 33a and 31a is 0.520". Thus, the real-size thickness of the mount would be 14.17 mm.

Certainly, the face of the "new" mount that surface 31a contacts is the reference datum from which the back flange is defined. (In the case of the EOS/EF mount, it is measured from the equivalent of surface 33a on the adapter.



> - The pin connectors on the newer mount side are the same as EF's ones, they just added 3 extra pins, so the communication protocal would be same as EF.



As I said, the patent says that with a "new" lens the protocol is different from the EOS/EF protocol, but that when an EF lens was attached, the body would use the old protocol.

Best regards,

Doug


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## micromirror (Mar 19, 2011)

But where are the rest of the patents?


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## dougkerr (Mar 19, 2011)

Jonathan,

For further reference, in US Patent application 2011/0052185 (in which the figures seem to be identical to that shown for the Japanese application), the text discusses that the difference between the flange back of the "new" body and the flange back of the "current" [EOS] body is equal to the "thickness" of the adapter, "C", of which they then say (with respect to Figure 2):



> The thickness is a
> distance in the direction of the optical axis from the camera
> body side installation surface 31a to the lens side installation
> surface 33a



Best regards,

Doug


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## Jonathan (Mar 19, 2011)

Hello dougkerr,

I meant that the inner portion ( where the screws are mounted) of the new mount side of the adapter, slightly protudes from the outer portion of the adapter (new mount side) Ã la or much like the canon FD lenses where the rear element portion of the lenses protudes and goes into the camera body. 

http://www.mir.com.my/rb/photography/companies/canon/fdresources/fdlenses/85mm.htm


We don't have many informations about the new camera mount, toward the new camera body female bayonet. 


Considering that Canon EOS and Canon FD flange back were expressed in millimeters and were exact numbers, respectively 44mm and 42mm; i guess it will be an exact number for the new mount too.

It means 12mm or 14mm for the adapter length.

* A 12mm adapter means that an APS-C size mirror box could fit, but in a very tight fit.
(I made measurement on my rebel, measuring the distance between the EF mount and the mirror at it uppest possition when it lays flat under the viewfinder with the Bulb mode. I've found a little less than 12mm, in reality something much close to 11.5mm.) 
That's why i guessed the adapter could measure 12mm, i thought Canon would keep the mirror but i've realized in the patent that they won't.

So you're right, the most likely adapter length would be 14mm.

* A 14mm adapter means (as expressed in the patent) that an APS-C size mirror box won't fit at all.
=> It's really a mirrorless camera, because they mention the lack of a mirror and its associated Phase Detection AF device in the new mount.
Furthermore, we don't have any specs about sensor size. Without a mirror they would put anything they want. It could be Full Frame 24x36, Canon APS-H, APS-C size or even smaller than APS-C. After all the adapter is made for APS-C EFS lenses...so APS-C is the most likely.

From this point, we can say unanimously that new mount flange back distance will be exactly 30mm (44-14=30).

=> The new camera will NOT BE a kind of fusion between an EOS RT (OVF with fixed pellix mirror) and a small mirrorless camera such as a samsung nx, even with the addition of the OVF.
It could have been interesting for me, but some user at the time of the EOS RT repported the lack of incoming light and flare/ghosting issues due to pellix mirror. EOS RT wasn't a succes. I think that's why Canon doesn't want to do the same mistake again.

In fact, there is only one way to follow for Canon. 
The mirrorless offering is already quite huge: 
* Olympus/panasonic Âµ43
* Samsung NX
* Sony Nex
* The future Nikon mirrorless with 16mm diagonal length sensor (x2.7 crop factor)

After the huge enthusiasm around the Fuji X100 and the hard beginning of Sony nex (only 3 lenses available), i bet that Canon will release a RANGEFINDER APS-C based sytem !!! 

A 30mm flange back is close to other RF flange back of the past such as Contax G&RF and Nikon RF...

http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html

This new canon Digital RF sytems would sit right beetween high end compact camera (Canon G12) and bigger entry level DSLR (canon eos rebel/xxxd) in term of compactness.
For the price this won't be that simple...i let you imagine the price.
This new sytems could be a poor's man leica M RF competitor of the digital era (with liveview and AF). We could expect it would cost something between 1000~2000â‚¬.


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## Admin US West (Mar 19, 2011)

From the patent:

[0004]In response to the desire to decrease the size and weight of digital single reflex lens cameras, in recent years a new type of single lens reflex camera that differs from the conventional single lens reflex camera has been proposed. The new type of single lens reflex camera is not provided with a quick return mirror for guiding the imaging light flux to a viewfinder, and the flange back is shorter than that of a conventional camera. The new type of interchangeable lenses having a short flange back that is compatible with this new type of camera has been proposed. However, these new type of interchangeable lenses cannot easily handle a variety of photographic conditions because there are few models. Therefore, there are cases in which it is desirable to use in the new type of camera the conventional type of interchangeable lenses that have already been introduced to the market and for which there are ample models and quantities. Thus, a conversion adapter for connecting the conventional type of interchangeable lenses with the new type of camera body is necessary. The functions required of this conversion adapter generally include matching the differing mounting profiles of the lenses and the camera body, matching the differing flange backs of the lenses and the camera body, and not hindering the communication system between the lenses and the camera body.


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## dougkerr (Mar 20, 2011)

Not that it matters much, but I have spoken of the flange back for the Micro Four Thirds system as "20 mm", whereas I see it often described as "about 20 mm" (no definitive value being cited).

There is a report from a fellow who, from a a T mount-to-Lumix DMC-G1 adapter, concludes that the Micro Four Thirds flange back is likely about 19.2 mm (recognizing that the adapter might have an offset for "safe infinity focus" built in, so perhaps the actual nominal flange back is a little larger than that).

Thus it might be that the nominal flange back for the Micro Four Thirds system is exactly half that for the Four Thirds system (which has been stated as 38.67 mm), or 19.33 mm.

Best regards,

Doug


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## Jonathan (Mar 22, 2011)

Hello,
I've found an interesting rumor from June. 

http://photorumors.com/2010/06/09/canon-aps-h-1-3x-mirrorless/

Now, it seems pretty plausible after that mirrorless patent came out.


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## dougkerr (Mar 22, 2011)

Jonathan said:


> Hello,
> I've found an interesting rumor from June.
> 
> http://photorumors.com/2010/06/09/canon-aps-h-1-3x-mirrorless/
> ...


Might make sense.

The EOS line has to date had three nominal frame sizes. It might be that the New Canon Thing (NCT) would also embrace bodies of differing format size, with something like 27 x 18 mm (32.44 mm image circle requirement) being the largest (0.75 of full-frame 35-mm format).

Then the "smaller" bodies might in fact have the rumored 18 x 12 mm format (0.50 of full-frame 35-mm format).

That would be a 3:2 ratio between the format sizes in the family, probably a sensible spread.

I have made no attempt to ascertain the design limits relating image circle to to such things as mount throat and back flange distance, so I'm in no position to opine on the design credibility.

You earlier suggested that you believe the mount implied by the patent would not support a frame size larger than what you call "APS-C" (by which I assume you don't actually mean the APS-C frame size but rather the Canon "1.3x" frame size often spoken of as "APS-C", perhaps nominally 22.3 x 14.9 mm). (The APS-C frame is 23.4 mm x 16.7 mm.)

Best regards,

Doug


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## Admin US West (Mar 22, 2011)

dougkerr said:


> You earlier suggested that you believe the mount implied by the patent would not support a frame size larger than what you call "APS-C" (by which I assume you don't actually mean the APS-C frame size but rather the Canon "1.3x" frame size often spoken of as "APS-C", perhaps nominally 22.3 x 14.9 mm). (The APS-C frame is 23.4 mm x 16.7 mm.)
> 
> Best regards,
> 
> Doug



Doug, I think you have a Typo in there, 1.3X crop APS-H is about 27.9 X 18.6 (1D MK IV) while 1.6X crop APS-C runs about 22.3 X 14.9.


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## dougkerr (Mar 22, 2011)

scalesusa said:


> Doug, I think you have a Typo in there, 1.3X crop APS-H is about 27.9 X 18.6 (1D MK IV) while 1.6X crop APS-C runs about 22.3 X 14.9.


No, I was speaking of the actual APS-C frame size, not the various digital camera frame sizes that are somewhere in that neighborhood and are often spoken of as "APS-C".

The APS taken frame size is 30.2 mm x 16.7 mm.

There are three "delivery crop" frames standardized:

APS-H: 30.2 mm x 16.7 mm (1.808:1) (this is in fact the taken frame size).
APS-C: 23.4 mm x 16.7 mm (1.401:1)
APS-P 30.2 mm x 9.5 mm (3.179:1)

Best regards,

Doug


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## dougkerr (Mar 22, 2011)

My apologies. I was in fact in error regarding the APS-C frame size (I picked the numbers up from an old table that I had somehow screwed up, without looking at it).

Here is the correct info:

The APS taken frame size is 30.2 mm x 16.7 mm.

There are three "delivery crop" frames standardized:

APS-H: 30.2 mm x 16.7 mm (1.808:1) (16:9 would be 1.778:1) [this is in fact the taken frame size - it is "full frame"]
APS-C: 25.1 mm x 16.7 mm (1.503:1) (3:2 would be 1.500:1)
APS-P 30.2 mm x 9.5 mm (3.179:1)

Sorry for the error.

Using the "full-frame 35-mm equivalent focal length factor" convention, an actual APS-C frame size (not found, within 5%, in any digital cameras I know of) would be considered "1.44x".

So it's probably not a bad *metaphor* for such frame sizes as 22.3 x 14.9 mm ("1.61x" - EOS 60D) and 27.9 x 18.6 mm ("1.29x" - EOS 1D Mark IV).

Oh, wait - they call the latter of those sizes "APS-H". Well, that's actually 30.2 x 16.7 mm. So it would better to call the 1D4 size "APS-C".

Glad I don't have to decide that.

Who does get to decide that?

As for me, I use "APS-C" to mean "APS-C".

Best regards,

Doug


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## Admin US West (Mar 23, 2011)

Jonathan said:


> If you have seen the diagram you would immediately understand that the new mount can only support APS-C format sensor.



This diagram?

No dimensions, and no requirement to draw it to any particular scale.

From this, you can determine the sensor coverage? I see no information about the lenses, they are what determines coverage, nothing else.


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## dougkerr (Mar 23, 2011)

scalesusa said:


> This diagram?
> 
> No dimensions, and no requirement to draw it to any particular scale.



True, but the "front" face exactly matches in proportions every feature of an EOS mount. Thus, if it the rest of it is drawn to the same scale, we can determine that scale to a high precision.



> From this, you can determine the sensor coverage? I see no information about the lenses, they are what determines coverage, nothing else.



Yes but there is an interaction with the mount throat diameter.

If in fact the lens design places the exit pupil at the mount throat (hard to do and not necessarily desirable from several standpoints), then the throat does not constrain the image circle. For an exit pupil forward of that, the mount throat does constrain the image circle.

Best regards,

Doug


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## Jonathan (Mar 23, 2011)

dougkerr said:


> Jonathan said:
> 
> 
> > Hello,
> ...



I'm pretty agree with you.
The new "NCT" might be a kind of a new EF-C (compacted or a EF "downsized").

If we look at the proportion, the new flange back distance (30mm) vs EF flange back distance (44mm), is approximately 70 percent of the actual EF flange back (30/44=0.68).

The sensor surface of an APS-C(x1.6) is ALSO 70 percent of an APS-H sensor surface.
APS-H size (in millimeters) : 27.9mm*18.6mm= 518.94 squarred millimeters
Canon APS-C size: 22.3mm*14.9mm=332.27 squarred millimeters

APS-C/APS-H ratio = 332.27/518.94 =0.64

It means, that we can consider these new system as a mirroless EOS sytems in reduction, with a reduction factor of 30%.
It also means, new lenses, design for an APS-H (33.53mm image circle) coverage, smaller than EF Full Frame lenses of at least 30%. 
For example can you imagine a 24-70mm F/2.8 L equivalent, that would measure 85mm in length and 58mm in diameter instead of 123.5mm (length) and 86.45mm (diameter) with the same performance and even lighter?? :

IMHO the APS-H (x1,3) is the first choice for this new mount, at least for the high-end, RF style (with EVF or hybrid), pro bodies.
Thus EF-S lenses + adapter would work on a cropped mode (~70% of available pixel).
It would give 10.3Mp from the actual 16.1 APS-H sensor of the 1D mk4. It's not the best, but it's quite acceptable (remember that it would be the only solution to recycle EF-S lenses, in the other hand it would not be the optimal use of the new mount abilities and it would help Canon to sell new mounted lenses and existing "FF" L lenses). 

At the lower-end, canon has just to keep actual APS-C sensor for this new mount, and make "Samsung NX" alike bodies with built-in EVF or something with pellix.

I don't believe in the introduction of a smaller than APS-C sensor, a 18*12 sensor doesn't make sense at all with such a flange back, unless they keep a mirrorbox, but they won't and it already exists ( Olympus E-volt DSLR series, such as the e-620). 
Plus Canon would put some money in R&D for a new type of smaller sensor. They don't need to do this, they already have all the materials and technology to create a new mount almost effortless.
And who cares about the aspect ratio in the entry-level consumer range ?? There's already Samsung nx and nex against 4/3, plus with APS-C (x1.5) (slightly bigger than those of Canon). 

Best regards,

Jonathan


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## dougkerr (Mar 23, 2011)

Hi, Jonathan,

Interesting observations.

I'm not sure how matters of sensor area fit into the thought process.

It is interesting to note that, among all the existing *SLR-based* still camera systems (that I have data for), the flange back distance is never less than 0.94 times the diagonal of the maximum system frame size (typically 43.26 mm, based on full-frame 35-mm as the "mother" size), and (if we exclude the "T-mount", not actually a camera system) is never greater than 1.09 times the mother frame diagonal.

If we think of the New Canon Thing having a "mother" frame size of 28 x 18.5 mm ("1.29x"), as some have speculated, then for the 30.0 mm flange back speculated upon here, that ratio would be 0.89.

That would not necessarily rule out a _bona fide_ SLR version of the system, but it might be iffy.

Best regards,

Doug


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## Jonathan (Mar 23, 2011)

dougkerr said:


> Hi, Jonathan,
> 
> Interesting observations.
> 
> ...



Interesting, but those ratios can only be applied to standard SLR (with a mirror-Box). Plus FD flange was 42mm, less than 43.26.
The new system is MIRRORLESS, so this rule doesn't make sense.

And Mirrorless allows optical engineers more freedom in their designs, especially for wide compact prime (the rear element could protudes and goes deeper in the body cavity).

An extrem mounting of a wide lens to give you an example:
http://www.16-9.net/lens_tests/15mm_test1.html


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## dougkerr (Mar 23, 2011)

Hi, Jonathan,



Jonathan said:


> Thus EF-S lenses + adapter would work on a cropped mode. . .


Always nice to see "cropped" used correctly (not to mean "smaller than something else we often think about").

Thanks.

Best regards,

Doug


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## dougkerr (Mar 23, 2011)

Hi, Jonathan,



Jonathan said:


> Interesting, but those ratios can only be applied to standard SLR (with a mirror-Box).



Is there an SLR without a mirror-box?



> Plus FD flange was 42mm, less than 43.26.



Yes, a ratio of 0.97 (I said "never less than 0.94").



> The new system is MIRRORLESS, so this rule doesn't make sense.



I don't know that the New Canon Thing system will not admit models with a bona-fide SLR viewing mode. (Maybe you do.)

Best regards,

Doug


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## Jonathan (Mar 23, 2011)

If you'll want a bona-fide SLR viewing mode, i'm pretty sure that the EOS System will continue to exist, at least for Pro's so you know what to do.


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## Jonathan (Mar 23, 2011)

> > The new system is MIRRORLESS, so this rule doesn't make sense.
> 
> 
> 
> ...



Maybe there will be models with OVF, but it would be either with the help of a RF style OVF or a traditional OVF via a semi-transparent mirror (like the EOS RT).

Best regards, Jonathan


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## dougkerr (Mar 23, 2011)

Hi, Jonathan,



Jonathan said:


> ... or a traditional EVF via a pellix mirror.



What would that mean?

In any case, you perhaps speak of a _pellicle_ mirror ("Pellix" is the name of a camera model)..

Best regards,

Doug


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## Jonathan (Mar 23, 2011)

Sorry it was a mistake in typography. 
Best regards.


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## Jonathan (Mar 23, 2011)

For me MIRRORLESS means every camera without slapping, full reflective mirror.

Fixed Semi-reflective mirror camera still have a mirror, so it could be named SLR, but it is more an hybrid construction between mirrorless and conventional SLR with a quick return mirror.

Plus the patent clearly shows (in section 0015) that "a quick return mirror and a dedicated focal point detection unit are not provided in the camera body."

=> No mirror at all
or 
=> Fixed pellicle mirror with either an OVF (like eos RT) or with an EVF (like Sony Translucent, SLT slr)

Best regards,

Jonathan


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