1D M4 how do I remove lens after broken lens release button

[OldenFrog]

During a weding shoot the leans release button brok. How do i remove the leans?

[TCampbell]

You may need to call Canon.

The mounting ring on the lens has a tiny hole in it.  The lens flange on the body has a tiny spring-loaded pin.  When you mount a lens (red dot on lens lining up with red dot on body) that pin is pressed into the mounting flange until you rotate the lens far enough that the hole aligns with the pin and the pin locks into the hole.  The sole purpose of the lens release button is to retract the locking pin.

When you press the button, it pushes against a metal tab which pulls the locking pin back.  You may actually be able to see a tiny bit of that tab on the lens-facing side of the release button (through the tiny gap where the button fits into the body.)  If you can press that metal tab back, it will release the pin.   

The release mechanism is fairly simple... it seems as if it'd be hard to break.  If the lens is trying to twist (somehow jammed) then it can make it so that the pin does NOT want to retract.  If I attempt to rotate a lens which is locked on my camera body I can feel just a very tiny amount of play (which is normal.)  If you're lens is jammed in and putting sideways pressure on the pin then it probably wont have any play at all - and that might make it hard to press the lens release.  

[Mykolas]

Hi OldenFrog!

If the lens is still stuck on the camera, they will need to be sent to our Factory Service Center so the lens can be removed and the release can be repaired.  To start the repair process, you'll need to complete a Repair Request on our website.