EF-S 18-55 becomes EF 18-55

[Arctirus]

I happened to see this while I was surfing and thought some of you 10D owners might appreciate it.

The article shows a home conversion that changes an EF-S lens to EF.

http://www.robgalbraith.com/ubbthrea...b=5&o=&fpart=1

[DownByFive]

I'd like to see someone try it with the $800 EF-S 10-22mm I'm sure a hacksaw would cut through the metal mount like butter...

[Arctirus]

If that can be done it makes me wonder why there is a such thing as EF-S at all. It seems like it's just a restriction made so that if you want to use those lenses you have to buy a new camera.

[Photo-John]

If that can be done it makes me wonder why there is a such thing as EF-S at all. It seems like it's just a restriction made so that if you want to use those lenses you have to buy a new camera.

My understanding was that the rear lens element on EF-S lenses would make contact with the mirror on cameras other than the 20D and the Digital Rebels. I figured it was an unavoidable design limitation. But maybe not. One thing I'm curious about is focus on the edges of the lens. I think it's safe to assume that Canon designed those lenses, optically, to work best mounted with the EF-S mount. Changing the mount would probably also change the focus a bit. From the photos in the post, I couldn't really tell excatly what was done. I assumed that the rear element of the lens needs to be moved out a little. But that would change the distance from the focal plane, and screw up the focus. So, obviously, there's something I'm missing or don't understand here.

[SmartWombat]

OK, so they fill the back of the plastic lens mount with epoxy.
Then they cut off the moulding that protects the rear element as it extends towards the mirror.
In the process it cuts into the epoxy, which forms a new back to the lens.
Paint that black with a pen and it's done.

The mount is untouched. The position of the mount flanges and the lens contacts ere unchanged. All they've done is hacked 5mm off the back of the lens.

If you look over the original article (http://members.cox.net/byteseller/EFS-WEB/EFS-WEB.html) he measured, profiled, tested, and at shortest focal length the 18-55 EFS lens does not hit the mirror on his 10D.

So, is the EF-S just marketing?
Or is the 18-55 just pure luck that the lens doesn't extend too far, and soemting like the 10-22 will definitely damage an EF body?

[Arctirus]

So, is the EF-S just marketing?

That's what I'm starting to wonder. At least with this lens it seems to be.