Expert: David Silver - 9/13/2005

Question
Hi David:  You are one brilliant person.  It was just as you suspected...an M adapter on the lens.  You sure know your stuff.  Also makes me feel stupid, but also made my day.

J. H. Thomas
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Followup To
Question -
Hi David: I have another Canon RF lens that I need to ask you about.  It's a heavy metal all-chrome 135mm f3.5 lens with the SN of 59202. The filter ring size is 48mm.  The base of the lens has a bayonet mount rather than the 39mm screw mount.  The bayonet has the "tongue" of the Leica M mount (like the adapter ring you told me about) along with 3 flanges (2 of the same size and one smaller one).  The mount has the cut out section leading to the tongue.  There is also an inner brass flange just like the screw mounted lens for my Canon IVSB RF camera. Below the bayonet mount are 3 cut-out half circles plus a notch near another smaller notch with the red alignment dot.  I am guessing the lens is for a Leica M body.  I can supply you a photo if needed.  If the lens is for a Leica M camera, is there an adapter to convert it back to a 39mm screw mount body?  I don't own a Leica M body.  The lens is clean and extremely good condition. Thanks again for your help.  
Answer -
Hi James,

I suspect what you have there is another adapter that's been screwed onto the lens so tightly it appears to be part of it!  The Leitz adapters are the most valuable, but there are a number of Japanese models that are just as good and much less intrusive without all that signage stamped into them.  Get a dish cloth, grab hold of the teeth on the mount, and see if it will release.  It will probably require a bit of elbow grease until it "pops" suddenly, and then screw off with ease.  Give it a try, and get back to me with the result.

In the meantime, to answer the last part of your query, you cannot adapt a Leica M mount lens to 39mm screw mount camera.

Best wishes,

David Silver

Answer
Hi again,

Yep, I thought so!

To finish answering your question, the Canon 135mm f3.5 with that serial number dates to the mid 1950's.  It's a relatively common model, but also a fine performer.  A truly excellent example with its proper front and rear caps would sell for around $75.  In the proper case with the accessory viewfinder can go up to $125.  Nice, but very common.

Best wishes,

David Silver