Leica R - EF Mount Kit Installation Guide


This kit converts lenses with a native Leica R mount to a fixed Canon EF Mount to be used with EF Mount cameras. This mount kit does not offer any electronic feedback. This mount is considered "passive" in that there is no communication between the lens and camera. The conversion process is entirely NON-destructive and is fully reversible at any time. Installation requires basic mechanical aptitude and only involves a few screws. Some steps may vary depending on the specific lens you're converting. Our mount kits are designed and manufactured with very high tolerances in order to maintain accurate flange focal distance. However, it's worth noting, as is the case with any precision optical tool, the flange distance should be adjusted within 0.0005" (12 microns) in order to ensure accurate infinity focus.

Kit Includes: EF Flange, 6x M1.7 phillips pan-head screws
Tools Needed: #0 and #00 phillips JIS screw driver
Time Required: Approximately 10-20 minutes


Start by removing the six screws from the original Leica R mount. Sometimes these are phillips head, sometimes they're slotted. Some lenses may also have a 10-hole pattern. For these models, simply leave the longer "in-between" screws in place and remove the shorter screws that match the 6-hole pattern of our EF mount. Leave the Leica R mount in place. The new Canon EF mount will be positioned on top of the Leica R mount.


Once you've removed the these six screws, you can position the new Canon EF mount, aligning the witness mark with the center of the "Duclos Lenses" engraving on the mount. The mount can also be clocked in different positions as needed if you'd like an alternate orientation once mounted. 


Once aligned, ensure the holes line up as needed and you can insert the included M1.7 phillips pan-head screws. Hand tighten (0.4 Nm recommended). We recommend using a thread locker on the screw threads to ensure the screws are well fastened.



Duclos Lenses is not responsible for any damage caused during disassembly, installation, or reassembly. Mount installation and calibration is offered free of charge for all mounts purchased from Duclos Lenses. If you're not comfortable performing DIY mount installation, we're happy to help you. Don't hesitate to reach out to us via email, webchat, or phone anytime.