eosm, why not an ef mount instead

Why not go with an ef mount, automatically they would have tons of lenses, not have to engineer a new mount and new lenses. And size wise its not that much bigger.

burb1972 wrote in post #17420635
Why not go with an ef mount, automatically they would have tons of lenses

And that's possibly one of the core reasons.
If you view the mirrorless range as supporting rather than replacing the DSLR lines (many photographers buy a mirrorless to be their "light" camera alongside their DSLR) then it makes sense that you want to take as big a slice of that pie as possible. Thus if you release a different mount system you ensure that your system won't let you down. You'll get the similar profits the other brands get even from your own dedicated fan-base of established Canon photographers.
By releasing a new mount all customers have to purchase both camera and lens(es). It won't lose you much because if they don't go for your product then they have to buy into a 3rd part and get new lenses anyway; so you lose nothing and gain increased sales.

There might also be design choices on the mount size of the EF mount that meant that the new mount is superior (smaller/thinner) to thus best match it to the overall smaller camera size. It might also be due to the flange distance that is expected/used with EF/EFS mounts which could complicate downsizing the system to a smaller body overall (ergo the lenses would have required a deeper camera body and thus you lose on width - remember a DSLR is quite deep compared to a mirrorless camera. Thus there could be a purely practical reason for the choice (ergo not all economic).

the sl1 is slightly thicker. it just seems it would be a much better system if it was an ef mount given the limited amount of eosm lenses. once you add the adaptor its almost as big as a sl1. And if it was a better system, would canon care if it sold a t3i vs 2 eosm's.? I think a really good eosm would sell better than a T3i(viewfinder vs size, size would win in sales). It seems if it was smaller than an dslr and better than the competition( due to lens selection) it would be a gateway camera, leading more people to get stuck with canon.Plus now the ff cameras are coming down in price. I got my cherry 5dc for 500$ over a year ago. However, very valid points on previous post.

The smaller mount also allows having smaller lenses, making the all package much smaller than regular DSLRs.

Canon makes an ef/efs adapter as well. Pretty cheap too.

I have both the M and some EF series cameras. As I understand it - could be wrong - as the M has no mirror, the lens can be designed with the rear element at about the same position as the rear connector as no room needs to be provided to clear the mirror movement and the mount itself is much closer to the sensor. The EF and EF-S lenses are designed to allow the image to correctly hit the sensor with additional clearance to clear the mirror. This is why the M to EF adapter is used to give the required spacing that M lenses don't need.

As others have said it is much easier to make small light short focal length lenses when you have a smaller flange to sensor distance. This is because you do not need to make the lens design retrofocus, which tends to make for bigger lenses. Thats before you allow for EF lenses that have to accommodate a 35×24mm image circle coverage. So your mirrorless with standard and wide lenses will be much smaller. This is also the same for traditional 35mm rangefinder cameras though. Just look at the size of say a 35mm lens for Leica compared to a 35mm for any SLR. I have a 35mm Olympus XA2 with a 35mm f/4 (I think) fixed lens, and the whole thing is the size of a 20 pack of cigarettes. It's a pretty tiny front element too considering, just because it can be close to the film plane.

On the other hand it is useful to Canon to be able to have a fully matched adaptor that can allow telephoto lenses to be used using the EF mount. Even in the EF-s mount you will notice that the longest lens in an EF-s mount is the 55-250 (for this the wide end focal length is important) from 70mm upwards there is no benefit in the lens design from using the smaller imaging circle. The physical size of the lens is pretty much dependant on the focal length and maximum aperture. A 70-200 f/4 still needs a needs a 50mm front element, a f/2.8 71mm. The lenger it gets the worse it gets so 400mm f/2.8 will need 142mm at the front as will the 800 f/5.6, the 600 f/4 gets to 150mm. If you are going to use any of those on your mirrorless there is no size advantage to be gained. At least you get a Canon designed adaptor to let them work as well as any other lens.

Alan

burb1972 wrote in post #17420635
Why not go with an ef mount, automatically they would have tons of lenses, not have to engineer a new mount and new lenses. And size wise its not that much bigger.

Heya,

No mirror box. Means less physical space needed. That brings the lens closer to the sensor. That means it has to be a different size and different mount. The EF & EF-S mount are built around a mirror box, and have to be a certain distance from the sensor. The M could not have had the EF/EF-S mount natively unless they physically made the EOS-M as thick physically as a mirror-box'd SLR, which totally defeats the purpose of making it mirrorless.

The adapter is the answer, as it does give access to the entire EF/EF-S line. And more. And you don't have to end up with a big giant "mirrorless" camera at all times, unless you just want to.

Very best,

burb1972 wrote in post #17420675
the sl1 is slightly thicker. it just seems it would be a much better system if it was an ef mount given the limited amount of eosm lenses. once you add the adaptor its almost as big as a sl1. And if it was a better system, would canon care if it sold a t3i vs 2 eosm's.? I think a really good eosm would sell better than a T3i(viewfinder vs size, size would win in sales). It seems if it was smaller than an dslr and better than the competition( due to lens selection) it would be a gateway camera, leading more people to get stuck with canon.Plus now the ff cameras are coming down in price. I got my cherry 5dc for 500$ over a year ago. However, very valid points on previous post.

That, ultimately, is why I got an SL1. With the M, you're stuck with a handful (even worse here in the US) of lenses, and if you "jut add the adapter", you might as well have the SL1, with its faster AF and the satisfying *chunk* of a shutter.

LonelyBoy wrote in post #17422733
That, ultimately, is why I got an SL1. With the M, you're stuck with a handful (even worse here in the US) of lenses, and if you "jut add the adapter", you might as well have the SL1, with its faster AF and the satisfying *chunk* of a shutter.

But that satisfying clunk is not the shutter it is the mirror. Most of the mirrorless bodies still have a mechanical focal plain shutter for still exposures, as they work better. So they have to close the shutter, flush the charge from the sensor then expose. The same happens for stills on a DSLR when using LV.

Alan

BigAl007 wrote in post #17423212
But that satisfying clunk is not the shutter it is the mirror. Most of the mirrorless bodies still have a mechanical focal plain shutter for still exposures, as they work better. So they have to close the shutter, flush the charge from the sensor then expose. The same happens for stills on a DSLR when using LV.

Alan

Right, my bad. My hands are way too shaky for LV, so I never use it anyway (which is another part of SL1 over M for me).

Thanks for all the great and informative replies.

http://en.m.wikipedia.​org/wiki/Flange_focal_​distance
difference between the eos M mount and the EF mount is one inch.

It bums me out that Canon will probably never make something like the Sony RX1.

I just want Canon to make a small, full-frame camera with the 6D's sensor.

mclaren777 wrote in post #17423433
It bums me out that Canon will probably never make something like the Sony RX1.

I just want Canon to make a small, full-frame camera with the 6D's sensor.

The Sony RX-1 is about $2,800 and is not without flaws. MaybeCanon could do a little better if they ever try to make something similar.