Canon 50mm f/1.2 LTM lens

Cleaning a Classic Canon f/1.2 LTM Lens

By Dave Powell

A while back, I snagged a beautiful Canon VI-T rangefinder camera for small bucks at a yard sale. It’s probably as close as I’ll ever come to owning a classic Leica. But it had issues:

  • Its unique base-plate “trigger winder” worked only sporadically.
  • There were a couple scratches across its 50mm f/1.2 Leica-Thread-Mount lens (apparently, a fairly common problem).
  • And the lens contained significant haze from aperture-lubricant out-gassing (also reportedly common).

But now that nice weather is returning to New England, a personal project I have in mind will require some late-night outdoor shooting. And I think this lens would be perfect if adapted to my Fuji X-Pro1. So I decided to fix it up as much as possible.

A Missing Instruction

Searching around, I found this excellent three-part procedure for cleaning the lens. It went pretty much without a hitch. Fortunately, the lens’s aperture blades looked fine, so I only had to clean the interior glass surfaces. So in the procedure’s PART II section, I skipped the tricky aperture bath.

But I’m writing this quick article because an important piece of information is missing from the procedure’s final PART III. It should have followed the line: “If you removed the inner and rear element only, clean each of them carefully and re-install.” FYI, the inner and rear elements come out of the lens casing as a screwed-together unit (shown on the right in the photo below). Its two glass components are then separated, cleaned, screwed back together, and at the end, the recombined lens assembly is returned to the casing (on the left) as a single unit.

BUT there’s only one correct way to align the lens assembly and the casing. One must ensure that the casing’s vertical metal tab (outlined on the left) slips into a machined groove (outlined on the right):

Aligning Canon f/1.2 lens components after cleaningYou’ll know that this wasn’t done properly if the final retaining ring at the rear of the lens refuses to fully screw in at the end of the procedure’s PART III.

Also note that the machined tolerances are so tight within the casing, that recombining these units may require gentle jiggling. And nothing should be forced.

Final Notes

I just wanted to write this piece for any other folks who want to clean this (or similar) Canon rangefinder lenses. And while my lens’s glass cleaned up beautifully, the two scratches across its front element are there to stay. So I’ll use a lens hood to keep light from hitting and glinting off them.

And… after periodically exercising the Canon VI-T trigger winder for nearly a year, it once again advances film properly. Patience pays!

–Dave Powell is a Westford, Mass., writer and avid amateur photographer.

Share this post:

Find more similar content on 35mmc

Use the tags below to search for more posts on related topics:

Contribute to 35mmc for an ad-free experience.

There are two ways to contribute to 35mmc and experience it without the adverts:

Paid Subscription – £2.99 per month and you’ll never see an advert again! (Free 3-day trial).

Subscribe here.

Content contributor – become a part of the world’s biggest film and alternative photography community blog. All our Contributors have an ad-free experience for life.

Sign up here.

About The Author

By Dave Powell
Trained in mathematics, physics, cosmology, computer programming and science journalism. Retired mathematician, award-winning technical and journalistic writer. Past winner of an international business-journalism equivalent of the Pulitzer Prize. And past author and editorial advisor for Sesame Street... where I regularly worked with Jim Henson and Kermit!
View Profile

Comments

Jukka Reimola on Cleaning a Classic Canon f/1.2 LTM Lens

Comment posted: 11/06/2024

Dave, I tip my non-existent hat before you, in admiration for both your skill and bravado to take a photographic lens apart. And to put in back together successfully. I'm not completely incompetent with tools, having built several bicycles from a pile of parts. Not to mention a new deck for our backyard. The idea of tampering with any photographic equipment, however, feels like performing a surgery to myself.
Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

Dave Powell on Cleaning a Classic Canon f/1.2 LTM Lens

Comment posted: 11/06/2024

Hi Jukka. Thank you so much, and I in turn tip my hat to you! Your bicycle- and deck-building skills are way beyond me. I wouldn't even know where to begin. In my case, it helped that the lens (like many older primes especially) is theoretically (though not always) fairly easy to take apart. And I had no little assistance from my favorite "Oracle of YouTube!" I'm so glad you liked this piece!
Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

Zach on Cleaning a Classic Canon f/1.2 LTM Lens

Comment posted: 11/06/2024

Hi Dave. I've enjoyed your other posts, especially your one-shots; this one is certainly different but is relatable: I've got a Canon VT (non Deluxe) that also had a sticky trigger; removing the baseplate and cleaning the chain drive fixed it for mine. Enjoy that lens! Canon screw mount glass has great character!
Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

Dave Powell replied:

Comment posted: 11/06/2024

Hi Zach I'm so glad you've enjoyed my One-Shot stories! I must do more, but have been working on a few longer pieces. After that, though! It's interesting about your VT's trigger winder. In my case, it was the exact opposite of "sticky." My winder wasn't always engaging (or fully engaging) the drive chain. Sometimes it would, sometimes it didn't, and sometimes it produced a partial advance. But when it worked, it was smooth. So I decided to just give it a little exercise whenever I walked by... and it eventually righted itself! Thanks again!

Reply

Leave a Reply

Your email address will not be published. Required fields are marked *

Leave a Comment

Leave a Reply

Your email address will not be published. Required fields are marked *