Canon EOS 5D Mirror Shave Instructions

Modifying a Canon 5D mirror to enable use of all Zeiss and Leica lenses

Special thanks to Gokurakudo Camera for originally publishing the modification


Assembled ingredients: the Zeiss 45mm f2.8 Tessar Pancake is here used as a test. It is suggested here that an air blower and an abrasive file are used; better tools for the job are almost certainly a vacuum and a Dremel. Beyond that, all you need is a rubber, scissors and a piece of card.


The centre point of the mirror is here marked with a white chinagraph, followed by markers 10mm distant from the centre.


Card masks are made from a 39mm wide strip of paper and folded as shown prior to installation around the mirror box. A very fine line of some caulking agent might also be beneficial to stop the pernicious and invasive metal and resin dust from spreading through the camera body.






Soft white eraser chunks of approximately 16mm in depth are used ingeniously both as spacers to hold the mirror in the raised position, and to contain dust.




With the messy area semi-secured, the moment of truth has almost arrived. Our Japanese friend attacked his with a file: I would be more comfortable with a precision rotary cutter.



Really cute 5mm kitty tape (aah!) is here used as a cursory final mask. Again, I would suggest rather more thorough masking than pictured here, with easily removed residue-free masking tape.


Without further ado, let hacking commence. We can only wonder at the meaning of the Japanese caption . . .


On this particular 5D, no more than 1.5mm of mirror housing and mirror was removed.



This relatively minor surgery is sufficient to allow the Pancake Tessar to mount, as well as the Planar 85/1.2 and Makro Planar 100mm – perhaps you have one knocking about in a drawer somewhere?



A 1.5mm modification was sufficient to allow mounting of the Zeiss 45mm f2.8 and the 85mm f1.2. The original modifier notes that a further 1mm shave was needed to mount the troublesome 18mm f4 MM version. This lens has a very small rear element that doesn't move during focusing, so it would be wisest to shave more deeply in the centre of the mirror to clear it. User reports suggest that a total modification of approximately 3mm would be required to clear the rear element of the Leica Elmarit 15mm. The Contax Zeiss 15mm only fouls the mirror at close to infinity focus, so a modest extra shave may be required to accommodate it also.

Naturally, this modification will invalidate your warranty. But then again, it may already have run out. It may or may note affect its resale value: a mirror-modified lens is a great bonus to some buyers; for others, it may be a cause for concern.

Alternate method: A safer, but rather more expensive, way to achieve the same end is to order a replacement 5D mirror from your local Canon outlet, modify it safely on a workbench, then pay a repairman to install the new mirror as a replacement. The cost of this is typically about $200-300. However, it sidesteps the problem of dust in the machine, and gives you a factory-spec mirror in reserve which can be re-installed if you need to sell the camera or send it back to Canon for repair.

This information is provide for illustration purposes only. We cannot be held responsible for any damage incurred during modification. Also, tolerances of individual lenses, adaptors and camera bodies make exact specification impossible: a necessary degree of trial and (hopefully not) error is involved.



Draw a straight line and follow it.

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