Is there a way to lock focus ring?

[Perio]

Hi guys, I hope you're doing fine. Maybe I have a naive question but it may help me a lot in my daily clinical practice. I use Canon 100L macro lens to take pictures of my patients in the clinic, and sometimes I wrap the camera in a sterile plastic bag during surgeries. Often while I'd wrapping the camera, the focus ring gets displaced, and then it's a pain to adjust it. The question I have is if there is a way somehow to lock the manual focus ring, so it always stays at the same level? The reason I need it to always stay at the level is to always have the same distance to an object, and when I crop the teeth/tissue is the same size. Thanks in advance!

 

[chromophore]

Sadly, no. The focus ring on EF lenses cannot be locked into a particular position strictly in between minimum focusing distance and infinity.

Certain EF lenses that are focus-by-wire, such as the EF 85/1.2L II, operate in such a way that turning the focusing ring while the lens is set to AF mode will not engage the focusing mechanism unless the shutter is half pressed. However, the EF 100/2.8L Macro IS is not such a lens: the focusing ring is mechanically linked to the focusing barrel assembly.

To address your situation, I recommend that you find some alternative method to adjust the focus after the camera has been sealed. One possibility is to use a device that grips the focusing ring through the plastic. Another possibility is to connect the camera to an external computer via EOS Utility, and use the computer to adjust the focus. Other photographers may come up with better ideas but these were what I could think of off the top of my head.

 

[candc]

Gaffers tape.

 

[Mt Spokane Photography]

Gaffers tape.

Be sure to switch the focus to the MF position as well as taping it. A rubber band (Wide) will do it as well.

 

[Perio]

Thank you for your time and suggestions, guys