I recently purchased some used camera gear, and one of the included items was a “Lens Kit“ by Peak Design, which helps you carry up to two lenses using a strap or on the Peak Design Capture. I always find myself fumbling with a second lens when out, so this seemed like a useful addition to my kit. While I was lucky enough to receive the Canon EF/EF-S version, I have recently switched over to using a Canon EOS R, which uses the new RF mount, which is incompatible with EF.
I had previously noted that the EF and the RF mounts were very similar in dimensions, but not compatible by design. As the Lens Kit doesn’t have any electrical or optical reasons why it can’t work, I wondered if it could be slightly modified to accept EF and RF.
Disassembly is quick. Just three philips screws on each side, connected by internally threaded rods.
Placing the ring over an RF lens mount shows that the obstruction is actually only this small area which I colored in with pen.
Moving the ring over to an EF lens shows that the removal of material would cut down on the ramp up when mounting.
And fortunately, this doesn’t seem to affect the strength of the EF lens once mounted.
I took a Dremel tool with a grinding bit and slowly filed down the section between the arrows, and added a smaller mounting ramp.
Trying this on the RF for the first time. It fits!
The Dremel took it most of the way, I finished up by using a small hand file and then the polishing wheel. Very smooth now.
Presenting, the Peak Design Lens Kit for Canon EF + EF-S + RF.
Mounting EF feels much like it did before. The change only reduced one of the three ramps, so I suppose it may make mate up slightly less likely, but I haven’t noticed a difference in practice. Mounting up RF feels almost native. There is a minor issue with detatching RF, as the lens can turn counter clockwise slightly too far to remove, but once I noticed it, it’s easy to anticipate that.
While I wouldn’t recommend everyone to grind down their mount rings, for me, this mod does exactly what I had hoped it would.