Help with Pentax SMC 50 1/4 repairs

autotak · Joined: 04 Dec 2009 Posts: 15

Hello all,

I am trying to convert a SMC Pentax lens for EOS by removing aperture lever and lever protector. I've run into a bit of trouble...

1. Is it possible to disconnect the lever instead of cutting it and still maintain stop-down functionality? I think the answer is no because the level is riveted to the "prongs" that are used to move the aperture "lug" on the lens.

Here's a picture of the offender:

2. The aperture rings (contained in the above picture, NOT in the lens) feel like they are grinding, some dirt entered the sliding mechanisms when I was removing it.

What should I use to remove the grease, and what grease(s) should I use in their place, and where should I lube it? It looks like brass piece where the set-screws go in have a thick grease on them and internally just a very light oil.

3. The metal band that has the distance information printed came off, as shown below. I'm 99% sure the orange diamond on the lens aligns with infinity when the rear element is 100% retracted (as close to lens mount as possible), I just want some confirmation.

4. What glue should I use to re-attach the ring? Super-glue?

5. Looking at the lens with a strong light, there seems like a lot of dust internally, on the front and rear elements. What tools do I need to take just the front and rear elements out?

Sorry for the long post, hopefully, I'll get some kind of response.

- autotak

martyn_bannister · Joined: 23 May 2010 Posts: 1151

Hi, the only advice I can give is that I think you are right about the position of the diamond. More knowledgeable people will correct me, but I would say that the aperture blades should NOT be lubricated and that all oil and dirt should be cleaned off them using isopropyl alcohol. Prefereably without actually dismantling them Smile

Good lock!

autotak · Joined: 04 Dec 2009 Posts: 15

Hi,

Thanks for your response.

Do you have any suggestions as to what glue to use for the distance ring?

Regarding cleaning and oiling the aperture, I am *not* talking about the actual iris, just the metal ring that has the lever shown above which has sliding "rings" that move when you click for each aperture position.

Thanks.
autotak.