Leica LTM Cleaning a canon 35mm f1.8

[sanmich]

Hi there
I just received a very nice canon 35mm f1.8. Incredibly compact lens and a perfect match on my IIIc (well, LTM 'cron would have been nice while jeopardizing my marriage 🙂
The focus is too stiff and I started to dismantle the thing. I've gone only up to the second helicoid mount, the one responsible for the RF roller to move according to the optical block movements. But then, no idea how to continue to the main helicoid, the one moving the optical block. I see no apparent screw.
I have assemble back the lens hoping that this half cleaning job will be enough but... well, now focusing is a tad easier but very uneven.
Any of you have dismantle such a lens once??
Thanks for the inputs Michael

 

[ferider]

Somewhere at home I have one with bad glass but good focus mount (which you can use for yours). You can have it for shipping costs only. Let me know.

Roland.

 

[Xmas]

Before you strip out optics, strip heliciods back to where you got to and clean with cotton buds just damp with Zippo fluid, then try a micro drip of PTFE liquid from dentist pick, into each thread, then reassemble. If it is near ok stick there, like you had a flush at stud.

Buy another sticky lens, for Rolands good mech, but be prepared to need to alter the shims to better than <0.001...

Then you will need another body... well two if your wife finds out...

Noel

 

[ferider]

Buy another sticky lens, for Rolands good mech, but be prepared to need to alter the shims to better than <0.001...

That's true, re-shimming might be necessary.

The problem with the 2nd body and the wife is this: what to do when she starts looking for one ? 🙂

Roland.

 

[John Shriver]

Also, more than shimming may be required to get accurate focus when switching optical blocks between focusing mounts. While I think Canon may have had a much narrower range of focal lengths of lenses (due to the benefits of statistical process control per Demming), they may still have made focusing mounts in focal length groups.

 

[Xmas]

Two problems

Canon did do tight controls and may not have used shims or helicod variants.

But they may have changed glasses between batches so the barrels may be different internally, for an optic swap the serials would need to be close. If you are lucky the optics will swap and work 100%. The key is to segregate the optics and dont mix so you can get back to a start.

It is easy easy to use cotton buds, zippo and PTFE liquid...

Noel

 

[sanmich]

Hi Folks

Here is the result of the mighty man vs lens battle :

first round, won by the lens. It simply won't open.

second round, I get help from John Shriver (and others) and understand I tried to open the wrong ring. Man (or should I say men...) prevails

Third round. Just when I think victory is mine, the lens, with a dramatic return of situation shows me who's the boss: it appears than trying to open the wrong ring (remember first round?) I slightly strained one of the lens elements. the helicoid is perfectly smooth but the whole lens movement is horribly uneven. Lens victory is total

Unless....

Roland, help! ... Lots of thanks for your offer!, I really could use a part source for this lens...
Can I send you the shipping fees by Paypal? How much would it be to California?
(Dunno if youre located in the US )

Thanks a lot to all the posters!!!

Michael

 

[ferider]

Sanmich,

got your PM and will answer today - let me see if I find the lens.

Best,

Roland.

 

[sanmich]

Thanks Roland!

BTW, what lubricant should I use after I solve all other problems?

The micro-tool lubricant is a bit pricy at 25$ not including shipping (only UPS??? doh???)