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07-03-2009, 07:57 PM   #1
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Pentax Asahi Takumar 135mm f2.5 repair

Maybe I'm looking for an easy answer and please re-direct this thread if it's already been done.

I just bought a Takumar 135mm f2.5 and the picture shows a bit of oil on the blades.

This will be my first time dismantling a lens so if there is a link or manual somewhere, could someone give me a hand with it. I don't have it in my hands yet, but before it malfunctions, I want to get the oil off. I have heard that lighter fluid works well..

Thanks in advance for the help!

07-03-2009, 08:54 PM - 1 Like   #2
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You are in luck. This lens has the easiest access to the aperture blades ever. I'm assuming your lens is the Takumar (Bayonet) 1:2.5 135mm. Focus the lens to its closest distance. Extend the hood. Grab the mount end with one hand and the exposed barrel between the hood and the focus ring with the other. That exposed barrel unscrews counter-clockwise. Find someplace to put those front two elements so they don't roll away. The aperture blades are right there. All of the Pentax, Takumar or Asahi 135mm f2.5 lenses unscrew like this, just ignore the bit about the hood if you have one of those.

Set the aperture ring to f22 to expose the blades fully. If they are stuck open, use the aperture lever to move them. I use naptha and Q tips to clean them; lighter fluid might be butane, naptha, alcohol or other things. The particular solvent doesn't matter, but it should dissolve the oil and evaporate quickly. Mineral spirits works too but evaporates slower than naptha. "Odorless" mineral spirits evaporates even slower. I don't think alcohol will work. Home Depot or Lowe's will have naptha in the paint department. Mine is labeled VM&P Naptha, which stands for Varnish Makers and Painters. So you can always use the rest for a batch of varnish. Q tips kind of suck and shed cotton threads everywhere, but I haven't found anything better. Soak one end in solvent, swab the solvent on the blades in a counter-clockwise motion, move the aperture lever a few times to work the solvent in, then dry the blades with the other end. You'll have to repeat this several times with a new swab each time. The blades won't move properly until all the solvent evaporates off. I have always worked from this top side of the blades and never bothered to figure out how to access the other side.

When the oil is gone and the blades work properly, swab down the flat black surfaces around the blades too. Oil gets deposited here when it gets on the blades. I also make sure the interior lens elements are completely clean. (I would not be surprised if part of this lens's bad reputation is from people using lenses with a film of oil on inside surfaces.) You can set the aperture ring to f2.5 and get to the inner surface of the rear lens group.
07-03-2009, 09:13 PM   #3
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Original Poster
Thanks!

Wow! I only posted a few minutes ago and already a response!!

It's obvious you've done it before, so I'll take your word for it. Another question... I have some industrial "cleaner/degreaser" that I use at work to remove everything from printed circuit cards (most of which are ESD sensitive). Will this work on the blades as well??? I think that it might... I may try it.

Thanks again and happy 4th!
07-03-2009, 09:56 PM   #4
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The potential issues with solvents are dissolving plastics (not a big issue with this lens), dissolving the glue between lens elements (also no problem here) and dissolving the lens coatings. I don't know how tough the lens coatings are.

I just cleaned one of these a couple of days ago so it's still fresh. They are dirt cheap when the oiled blades are mentioned.

10-24-2009, 11:37 PM   #5
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Thanks to Just1MoreDave

I dug up this old post while searching for info on, guess what, an oily old Tak 135/2.5.

Well, thanks to your post explaining what worked for you I may just have rehabilitated this old lens. It took about a dozen applications of naptha (I used contact cleaner made for electronics) but the aperture is finally closing all the way down instead of sticking at f.11.

So thanks Just1MoreDave - I appreciate you sharing what you'd learned.

mo
11-03-2010, 10:45 AM   #6
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QuoteOriginally posted by mo caraher Quote
I dug up this old post while searching for info on, guess what, an oily old Tak 135/2.5.
Exactly my story
Just cleaned it...seems to work fine now!

So thanks Just1MoreDave!
11-04-2010, 02:54 AM   #7
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QuoteOriginally posted by Just1MoreDave Quote
. . .Focus the lens to its closest distance. Extend the hood. Grab the mount end with one hand and the exposed barrel between the hood and the focus ring with the other. That exposed barrel unscrews counter-clockwise. . .
FYI, the non-takumar k135/2.5 comes apart in much the same way.
03-10-2011, 02:20 PM   #8
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I did the same too. It is very easy to take apart and cleaning the aperture blades is also pretty easy as well. I have a standing light that points upward and I put my lens open side down to clean the aperture blades. This way dust wouldn't fall inside the lens. I used lighter fluid as the solvent and it did leave some residue after it dried up. I gently rubbed them off with my finger (be really careful here as you can easily misalign the blades). The Q tips worked well but as the previous posting said it WILL shred lints on the aperture blades. They tend to get stuck in between the blades so be careful around the gap of the blades. Be sure to change Q tip frequently. I used about 6 for the whole job. It took me around 20 minutes to finish and wait for the blade to dry completely. Good luck!

06-22-2012, 10:28 PM   #9
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Dave... You are awesome!

Just got an oily Tak-bayonet 135 2.5 today and was amazed when it unscrewed as you said it would.
I actually had to put a large rubber band around the barrel behind the hood and mounted the lens on a TC
for extra leverage but it came loose. Cleaned with contact cleaner until front of blades was clean.
Hard to remove all oil from rear of blades but they work great now!

Just had to as another success story to this old thread.

If only all lenses were this easy to work on.



QuoteOriginally posted by Just1MoreDave Quote
You are in luck. This lens has the easiest access to the aperture blades ever. I'm assuming your lens is the Takumar (Bayonet) 1:2.5 135mm. Focus the lens to its closest distance. Extend the hood. Grab the mount end with one hand and the exposed barrel between the hood and the focus ring with the other. That exposed barrel unscrews counter-clockwise.

Last edited by SRT201; 06-23-2012 at 11:27 AM.
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