Read this if you cannot insert your Canon lens in the camera.

Coming back from a little nature expedition today, I found I still had the 200mm L on the Canon 5D, so I went to replace it with the 24-105mm L which usually makes its home on the body.

The only snag is that it refused to even fit into the breech of the bayonet on the body. I checked for damage on the lens’s bayonet and there was none. Hardly surprising as I had not dropped the lens.

I checked against my other two lenses – the 200mm L and the non-L 15mm fisheye. All three have a small Phillips head screw some 20 degrees counter-clockwise from the red mounting alignment dot, viewed with the bottom of the lens uppermost. No other protrusions exist around the circumference. So, it must be the screw.

I located my smallest Philips head jeweler’s screwdriver and, sure enough, the screw was loose. A moment’s work and all was well.

So if you run into this snag, don’t panic. And carry a Phillips screwdriver with you. A tad frustrating on a $1300 lens.