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Pentax screw mount lens repair

Dave Cheng , May 31, 2004; 10:53 p.m.

My old screw mount 135/3.5 has a sticky aperature. The lens is my first SLR telephoto lens that means a lot to me as it was a gift from my dear sister when I was a child. It is not cost effective to send it to a shop. Does any one know how to take it apart to acces the aperature mechanism? I was able to repair a Rollei projector zoom lens once. Half out of probably a dozen glass elements were in a paper bag when it was handed to me. I feel I am handy enough to do it myself. But I don't want to force it to figure it out. Hope someone can share his/her experience here. Thanks a lot.

Dave

Responses

Niko Koskela , Jun 01, 2004; 02:24 a.m.

Dave, Chris Sherlock has strip-down instructions for a 50mm Takumar on his site: http://homepages.ihug.co.nz/%7ESrawhiti/pentax50mmf1.4.html

I myself have not stripped down a 135/3.5, but various other takumars and all of those i could strip down following these instructions. I´d guess you can do it for the 135 too with those instructions. Actually stripping down a Takumar is quite simple, after you have stripped down one the first time, you know how to do it. The hardest part in disassembling was removing the "name ring" surrounding the front element... That will be difficult especially if there´s even lightest of damage on the filter threads.

Good luck ! Not that you need it... ;) Really !

Niko

P.S. Hopefully someone who has disassembled also the 135 can confirm that it´s not too different from other Takumars ?

Niko Koskela , Jun 01, 2004; 02:40 a.m.

Me again. Before too long someone will say you need these for removing the front ring: http://www.micro-tools.com/Merchant2/images/lr-kit.jpg

That would of course be ideal, but i have got good results (by being really careful, of course) with a piece of rubber glove, for grip, and a lens rear cap of a correct size to turn it.

For example, i needed to adjust the infinity focus on a SMC Takumar 85/1.8. The filter thread had a ding on it, and it refused to turn by hands with the rubber glove only (sometimes they can be removed that easily). I looked through my home for a correctly sized round object to fit the name ring, but not touch the lens. Finally i found it ! It was a Pentax K-Mount "push on" lens rear cap. With that arrangement i got the name ring off, and the filter thread was "repaired" at the same time! Of course, there´s also special tools for that...

Niko

Dave Cheng , Jun 01, 2004; 12:35 p.m.

Niko, thank you so much for replying so quickly. The infomation is wonderful. I think I will be able to work on my 135/3.5 now. Thanks again.

Dave

Dave Cheng , Jun 01, 2004; 12:48 p.m.

I'll need to fabricate a special tool for name ring removal too. Thanks again.

Dave

Dave Cheng , Jun 01, 2004; 10:51 p.m.

Wow! I got it done. It took me a whole day today though. I cut some double sided adhesive tape into small slices and taped them on the name ring. Then I used a rear lens cap to press on and turn it. It was quite easy to turn with a very slight pressure. I could have taped the tape slices on the rim of the lens cap instead. It would have worked as well. After removing the ring everything else is visible and not too hard to remove. I eventually had the aperature assembly out and cleaned. Yes there was some grease in there for some reason I don't know. I cleaned it with alchohol. It now works great.

Reassembling the whole thing back was a lot tougher then I thought. The screws were so tiny that it was very tough to put them back to screw in. In the proces of realigning infinity focus I had to dismantle and reassemble a couple of times. In the process I lost one tiny screw for fixing the aperature index ring. This is OK, With one missing it is hardly noticeable any way.

Now the lens is alive and well. Thanks a lot for the info again.

Dave

Niko Koskela , Jun 02, 2004; 01:23 a.m.

That�s good news Dave! Now you can propably work on any Takumar, and it won�t take whole day anymore!

Niko

Mark Littlewood , Jan 07, 2010; 08:21 a.m.

Hi - resurrecting the thread because I'm doing a full strip down of mine (super-multi-coated takumar) too after some idiot put a load of WD40 in there - it's the version with the tiny weeny pin that is pressed when the lens is mounted, they thought it was broken.

first problem: the spring in the auto iris mecahnism doesn't seem strong enough to return the iris to wide open... should my iris be 'effortless' to move (it isn't, but it's smooth and doesn't seem too difficult, and the blades are clean/dry now) or do i need to reinvigorate/replace the spring? It's not a disaster as i'm not going to use AUTO much anyway.

second problem: after adjusting infinity focus i clamp the focus barrel onto the brass ring using the three screws with washers, but the whole thing grinds to a halt then. i think the screws are hitting the metal behind - do i need to reassemble with the brass helix further out of the black barrel it screws into? do those threw screws clamping down really do the whole job of transmitting the turning motion?

third question: how much grease i should put in? i'm going to use white lithium grease, but have not put any in so far, and it slides smoothly but not lightly, not sure what quality of action i should be aiming for.

Any hints gratefully appreciated...
Thanks
Mark

stephen scovel , Jan 15, 2012; 04:37 p.m.

Bought a Takumar 50mm 1.4 and found two of the three screws for the front ring are missing. Where can I find replacements?

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