Not sure what is going on. My 1DXII body is losing the lens lock? I’ll shoot an event, and put it my car’s storage area. And often when I go to use the lens next time, the lens will come loose. It isn’t separated from the camera until I start moving it.
The lens on that body is a 200-400L, so a big boy. But because it is so big I handle the lens, not the body- so I don’t think I’m activating the lens release button. When it does fall off, it seems like it is after I’ve moved a bit- so like the lock mechanism is letting go, and then the lens is rotating and separating.
It never happens during use, only when I’ve stored it in my car. I pull the batteries and cards so I don’t have to lug them around.
Is this a known issue with these bodies (lens?). Once I put lenses on, they stay put. They lock up tight. It is something else? I’ve never had this issue before with other cameras, but it’s been 4-5 times where this has happened. I guess the button is getting pressed a bit and the lens slightly disengaging.
Sometimes the lens mount is loose and rotates or sometimes it is the mechanism in the camera that is sticking in the unlocked position. If you can isolate which then send only that one in for service. If not then probably send in both. But it is easier to check the lens mount for debris and tightness. Some people put a very small amount of light oil on the pin, but that's not always a good solution.
Does the lens release button on the body move smoothly and the lock pin doesn't stick when partially or fully pressed?
Does it happen with any lens the first time you mount it onto the camera after it was in the car, or only the 200-400?
Is the 200-400 mounted on the camera while in the car?
Also, the 'port' on the lens mount into which the lock pin slides on the lens should be perfectly round. If it's oblong shape, the mount should be replaced. It's much less a problem now because that port is reinforced, but the original EF super-teles just had a hole drilled in the mount into which the locking pin fit to lock the lens onto the camera. Over time with use and rotation between horizontal and vertical photos, the pin would push against the edge of the hole and elongate it to the point where it would allow the pin to be pushed down and for the lens to release from the camera. The lens mount flange appears to be plated brass, which is much softer than the metal of the locking pin. Even in the photos below, you can see that the slightly raised edge of the mount around the hole reinforcement has been slightly warped by repeated contact with the locking pin. But that wouldn't cause the problem you're experiencing.
Here's what the port on the lens mount should look like (and this is a 200-400):
I had this issue with one of my TCs (the old original 2x) where the pin was sticking. I had to always double check to make sure it was engaged. I do believe I sent it in for repair.
I looked over the camera and the lens. All seems to be in order. I’m wondering if the way I store and move the cameras was enabling something to bump the lens release button. Just weird that it is this body and this lens. I think I’ll switch the lens to another DXII I have and go from there…
Thanks for the input. I probably need to send these off to be worked on, been awhile. CPS CLA DXII and 200-400L gear?
Yeah, CPS will CLA those. But don't wait too long on the 1DXII. Canon Japan's support page indicates service support is scheduled to end in July 2026. With the 200-400 you have until 2031.
