Canon Serenar 35mm f/3.5 Clean, Lubricate, Adjust (CLA)

Pic 1

This Canon Serenar 35mm f/3.5 is in nice condition, but the aperture ring is a little stiff. Plus, I’ve already cleaned the other two so I might as well do the entire set.
I thought this one, being the smallest, would be the easiest. It wasn’t. I had a difficult time reassembling the rear section. For some reason the black painted plate was locking up the helicoid. I eventually got it and the lens works like new. The aperture is now fantastically smooth, partly because it is click-less from the factory.
You can read more about its history in another post.
(follow the images left to right, top to bottom)

17 thoughts on “Canon Serenar 35mm f/3.5 Clean, Lubricate, Adjust (CLA)

  1. When you remove the threaded outer ring and then the inner helicoid, is there a specific way the lens has to be set(i.e. lens focus distance) to re-thread the inner helicoid back on? I was curious if doing it incorrectly would result in the focus being off.


    1. It doesn’t matter how you mount the outer helicoid. It simply screws on around the lens section and is redundant. Also, it’s all thread, so there is no way to adjust the way it mounts.


  2. Cool, thanks. Lastly, if there is a small scratch on the black paint where you would use a spanner wrench is that going to need to be repainted, or is probably fine?


    1. Painting that black part would mostly be for cosmetic reasons. It’s unlikely to have an effect on the optical performance of the lens because it’s 180 degrees from the source of light.


  3. This is a fantastic teardown. I used this today to get to a bad breakout of fungus right by the rear lens, next to the iris blades. The fungus was cleaned up, but the damage to the optical coating is beyond repair. On the plus side, I learned quite a bit in disassembling and reassembling these lenses. Thanks for putting this together

    Liked by 1 person

    1. At the time I was using white lithium grease. It’s not a bad option, but I wish I could get my hands on something more intended for photography. It would be nice to have some lubricant that is slightly thicker. I have some lenses that are too easy to turn and even white lithium isn’t thick enough.


      1. thanks, I will go and get something off ebay, I have this lens just sitting, got it for $5 at the flea market, it needs CLA and should be good to go.I will follow your instructions as guide THANKS A LOT for the step by step disassembly and cleanup

        Liked by 1 person

    1. Thanks. I’ve used various chemicals such as alcohol and even acetone. Anything you use on your glass is at your own risk since you don’t know what effect it will have. The coatings could be removed without you even realizing it.


  4. Hi mark I got into the canon 35 3.5 I jut got and thought it was a different lens. The second set of threads
    Was not there. I did mount it on a lumix g1 to test after cleaning the lens elements I could hardly focus it
    The haze and fungus was so bad, it cleaned up wonderfully. It will not focus to infinity not sure where I made then mistake. I did not do all the steps only the front inner and rear elements. I may have missed the black pin to align the front lens you referred to. I’m surprised how sharp this 70 year old lens is wide open at 3.5 feet
    Closest I could get. Thanks for the site I will work on to getting the paint chips out of 85mm f2 at first I thought it was the iris blades. Thanks again d benedict


      1. Hi mark, I have learned a lot, apparently someone had worked on both the 35 3.5 and the canon 85 f2
        That came with a canon canon iib the 50 mm was fine.

        On the 35 3.5 i could not use my marks when dissassembling it because it was wrong to begin with. After hours of craziness I got it back together focusing on infinity and everything fell into place it cleaned up nicely
        And may be sharper then my 3.5cm.
        The same with the 85 mm f 2 it was all screwed up.i had to clean helicoid 3 times, it is is fine when clean but as soon as I added the Japan hobby lube it was to tight and I just used a minute amount.

        The lens is together correctly now clean glass and focusing correctly, but focusing moves the aperture ring and the aperture ring will move the focus ring. The aperture ring is loose if I tighten it it’s worse

        There is no grease on the helicoid now,this was a test to see everything is in place, it is I’m wondering if I got the focusring screws mixed up and no grease somehow is the culprit. Any ideas.

        Thanks again for a great learning challenge, now it’s done. Dave benedict


  5. Hi,

    Thanks for posting this, It was quite helpful while doing a CLA on my lens. Thank You!! Thank You!!

    Just an FYI…that second helical on the rear of the lens is the rangefinder cam, its there for the rangefinder arm/follower in the original film camera to press against. It needs to be in the correct position (indexed correctly) for it to move in and out as you focus the lens. On a digital camera I suppose this may not be important. On a Leica or a Leica clone ( Canon, Leotax, Nicca, Fed, Zorki, Etc.) rangefinder type camera, it’s quite critical.

    I use mine on both and love it… 🙂


    1. I’m glad you found this helpful. It’s good to know what the helical on the back is for. I shoot with modern cameras, but do have the original Canon camera these lenses were made for.


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