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Any future for Canon EF-S lenses ?

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wadia13 said:
wadia13 wrote: Can you explain why 3rd parties can't take advantage of short back-focus while Canon can?
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My guess is because they make just one optical design to be used on all DSLRs. It's most cost effective for 3rd party makers to design a lens once for the longest flange-to-sensor distance (Nikon at 46.5mm), then adapt it to the other shorter DSLR systems. The same way Nikon lenses are easily adapted to EOS, but not the other way around.

Of the APS-C DSLR makers, Canon has the shortest flange to sensor distance (44mm, or ~41mm for EF-S).

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Unapologetic Canon Apologist :-)
 
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Sigma 17-50 f2.8 OS competes quite well and there are a lot of fans of the Tamron 17-50 f2.8.
 
Lemming51 said:
Lemming51 wrote:
Lemming51 said:
wadia13 wrote: Can you explain why 3rd parties can't take advantage of short back-focus while Canon can?
Click to expand...
My guess is because they make just one optical design to be used on all DSLRs. It's most cost effective for 3rd party makers to design a lens once for the longest flange-to-sensor distance (Nikon at 46.5mm), then adapt it to the other shorter DSLR systems. The same way Nikon lenses are easily adapted to EOS, but not the other way around.

Of the APS-C DSLR makers, Canon has the shortest flange to sensor distance (44mm, or ~41mm for EF-S).
Click to expand...
That's exactly what I was thinking ... however, EF-S lenses are also allowed to extend 4-5mm behind the flange, for an even shorter back focus distance, so there is even more design freedom.
 
Shorthand said:
Shorthand wrote:
Shorthand said:
Lemming51 wrote:
Shorthand said:
wadia13 wrote: Can you explain why 3rd parties can't take advantage of short back-focus while Canon can?
Click to expand...
My guess is because they make just one optical design to be used on all DSLRs. It's most cost effective for 3rd party makers to design a lens once for the longest flange-to-sensor distance (Nikon at 46.5mm), then adapt it to the other shorter DSLR systems. The same way Nikon lenses are easily adapted to EOS, but not the other way around.

Of the APS-C DSLR makers, Canon has the shortest flange to sensor distance (44mm, or ~41mm for EF-S).
Click to expand...
That's exactly what I was thinking ... however, EF-S lenses are also allowed to extend 4-5mm behind the flange, for an even shorter back focus distance, so there is even more design freedom.
Click to expand...
that's already included in the ~41 mm estimate. the mount for EF and EF-S is the same, 44mm, same flange distance!

The mirror in the 1.6x crops is just a bit smaller, so the lens can stick a bit more into the body than on FF => EF-S. To protect these protruding elements, Canon made the EF-S protruding back mount. But some EF-S lenses wouldn't even need that, e.g., the 55-250 would be fine as EF, apart from the reduced image circle.

I agree with the idea that third parties don't use it, because they make one model for several flange distances.
 
Olga Johnson said:
Olga Johnson wrote:

Did you notice that the OP wrote 4 years ago? :)

--
Olga
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The person the revived the thread did. He revived the thread to point out that after 4 years since the original question EF-S lenses are still alive and well. Guess everyone else missed it.
 
Ya know I think that is the BIGGEST JOKE in the camera business, as if Canon has taken advantage of it WOW. Just look at poor old Sigma that CANT take advantage of it,hmmm 18-35 1.8, Canon is not even in the same ball park.
 
davel33 said:
davel33 wrote:

Ya know I think that is the BIGGEST JOKE in the camera business, as if Canon has taken advantage of it WOW. Just look at poor old Sigma that CANT take advantage of it,hmmm 18-35 1.8, Canon is not even in the same ball park.
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Yeah, I've never read or heard of any criticism of 3rd party lens because they don't have the ideal back focus distance on a Canon cropped sensor body. Just never heard of it. Can anyone point to any source that makes this criticism and how it impacts picture IQ?
 
davel33 said:
davel33 wrote:

Ya know I think that is the BIGGEST JOKE in the camera business, as if Canon has taken advantage of it WOW. Just look at poor old Sigma that CANT take advantage of it,hmmm 18-35 1.8, Canon is not even in the same ball park.
Click to expand...
Yes, Canon hasn't taken much advantage of it. The 10-22 definitively hits the mirror at 10mm when mounted on FF, people have tried it, so for this they did use the reduce back distance.

One can look in the Canon museum, in the block diagrams. The 15-85, and the 17-55 f2.8 also reach into the mount, the older 17-85 seems not. The 18-55 kit lenses sure don't need it. The 18-135 STM seems to use it.

Basically you are right, one doesn't need the reduced flange distance to make good lenses - otherwise UWAs would not be possible at all anyway, that's what the retrofocus design is for. However, as the mirror-less cameras show, one can make lenses that are smaller. So, perhaps EF-S is the reason why the Canon 10-22 is smaller and lighter than all the competition.
 
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