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Pentacon 135mm f2.8 focus ring
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PostPosted: Sat Oct 13, 2018 3:03 pm    Post subject: Pentacon 135mm f2.8 focus ring Reply with quote

Hello everyone,

I bought a Pentacon auto 135mm on ebay and just received it. It is in a nice condition but I have a little problem with it. The focus ring does not go to infinity. It just stops between the 20 and 40 meters mark. Can this be fixed easily?

Cheers



PostPosted: Sat Oct 13, 2018 3:46 pm    Post subject: Re: Pentacon 135mm f2.8 focus ring Reply with quote

lolol25 wrote:
Hello everyone,

I bought a Pentacon auto 135mm on ebay and just received it. It is in a nice condition but I have a little problem with it. The focus ring does not go to infinity. It just stops between the 20 and 40 meters mark. Can this be fixed easily?

Cheers


quote to show your post. First posts have an anti spam filter.


PostPosted: Sat Oct 13, 2018 3:53 pm    Post subject: Reply with quote

A possible cause is something is jamming the travel...
If the lens was taken apart and the helicoid was installed wrong, it might exhibit this.
Another possibility is that the focus ring has slipped.

Does the lens render infinity sharp where the focus stops? if it does, that eliminates the first option and makes the second less likely.


PostPosted: Sat Oct 13, 2018 5:44 pm    Post subject: Reply with quote

If the lens actually reaches infinity, then the ring is in the wrong position - probably an easy fix. If the lens doesn't reach infinity, then you need to get a bit deeper in the lens, as Lightshow says, something is jamming the helcoid or it's in the wrong helicoid. I'ts a multi start thread ( as in a nut and bolt, which are single start ) and can be assembled in the wrong thread.

It's probably not a complicated lens, and well worth fixing.


PostPosted: Sat Oct 13, 2018 6:53 pm    Post subject: Reply with quote

I haven't tried focusing to infinity. I'm still waiting for my M42 to eos adapter. I'll let yiu guys know when I get it. And I agree it looks like a fantastic lens and i will definitely try to fix it


PostPosted: Sun Oct 14, 2018 10:21 pm    Post subject: Reply with quote

Another possibility would be part of auto aperture mechanism is bent and preventing focusing to infinity.


PostPosted: Sat Oct 20, 2018 12:17 am    Post subject: Reply with quote

Little update:

I fixed the lens this afternoon and it was a quick repair Mr. Green Had to only remove the base of the lens. There was a tiny little thumb screw(don't know where it came from) inside the helicoid which i guess was jamming it. The whole thing took only 5min and now i can focus to infinity Smile



Cheers


PostPosted: Sat Oct 20, 2018 1:49 am    Post subject: Reply with quote

Whoo Turtle Congrats


PostPosted: Sat Oct 20, 2018 5:43 am    Post subject: Reply with quote

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