50mm 1.8 lens stuck on my XTi

is this an older 35mm 50mm 1.8 lens?

Last weekend I updated my firmware from 1.0.4 to 1.1.1 (with the lens on the camera) and now I cannot remove the lens.

The firmware update seems to be a stumbling block here :)
Seriously - try not to push the lens to the end. When it reaches the end try rotating it backwards a little bit and see if it works. There's not much that could happen with EF 50/1.8 Mark II version. It doesn't have any screws on the mount. Which version of the lens are you talking about? Plastic (Mark II) or metal version (Mark I)?

It's the plastic newer one.

[[I have used my Canon 50mm 1.8 lens on my XTi for a while now and never had a problem removing the lens. Last weekend I updated my firmware from 1.0.4 to 1.1.1 (with the lens on the camera) and now I cannot remove the lens.]]

A software update preventing movement of a physical object? Now that's a feature Canon must have really been throwing some R&D dollars into...

That's what I thought, but I figured it was worth mentioning anyway. :)

Just wondering, since I don't have a camera in front of me .. but still:
Pentax lens for example, has a small *button* on the back which when pressed opens the aperture. Not sure if Canon is completely automatic, but if not could it be that post firmwire upgrade somehow the aperture ring got *locked* out. If your camera has DOF preview, try pressing/releasing this numerous times and then attempt releasing the lens. I know of 1 situation - this had helped, but not for Canon.
finally, i would SERIOUSLY AND ADAMANTLY recommend you NOT TO give too much pressure on the whole thing. You have a $80.00 worth of lens attached right now to a +$800.00 worth of equipment. If push comes to shove you can hammer away the lens (break the thing) rather than break the camera mount! Take it to a service center but please - don't end up breaking a $800.00++ equipment for a $80.00 lens.

[[That's what I thought, but I figured it was worth mentioning anyway. :)]]

Well true, I guess that's better than those posts where someone says "My camera doesn't work right. Why?" and leaves it at that :)

Hello Phil,

With the lens fully mounted and locked, does the camera still take pictures? If so, does the viewfinder image look normal or does it appear off-center? I'm thinking that maybe the mirror has become dislodged and is catching on the back of the lens mount. When you try to dismount the lens does it feel rough or tight? It could be that the lens locking/release pin is not fully retracting and has gouged the plastic lens mounting flange. In either case it sounds like you'll have to send it to a Canon service center.

By the way Baivab, on a Canon EOS camera there is no mechanical linkage between the body and the lens, the diaphragm is operated by a motor inside the lens.