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09-01-2021, 06:52 PM   #1
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Super Takumar 24mm/f3.5 Sticky Diaphragms

What is the solution to slow diaphragm blades opening back to full aperture and a stiff aperture ring? I have tried to "work" the aperture ring and pressing the auto pin many times and that does not seem to loosen things up. The auto aperture pin seems stiffer to press than other fully operational lenses.

09-01-2021, 07:08 PM - 1 Like   #2
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QuoteOriginally posted by Kingman Quote
What is the solution to slow diaphragm blades opening back to full aperture and a stiff aperture ring? I have tried to "work" the aperture ring and pressing the auto pin many times and that does not seem to loosen things up. The auto aperture pin seems stiffer to press than other fully operational lenses.
Usually sticky blades are the result of gunky old oil on the blades themselves and are not to do with a stiff aperture ring or pin. (Usually with this problem the ring or pin moves fine but the blades are slow to react.) So it sounds like in your lens something is bent, or it was taken apart and not put back together quite properly.
09-02-2021, 05:01 AM - 1 Like   #3
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Super Takumar 24mm/f3.5 Sticky Diaphragms

Heat soak causes the lubricants to move in between the diaphragm leaves. The blades will be sluggish or totally stuck. CLA is your need.
Itís rarely anything bent or loose.
The pin will be stiffer as itís fighting the resistance of the grease between blades

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09-02-2021, 06:05 AM - 1 Like   #4
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Like what others have said. I had a similar problem on the K 30/2.8 and K35/2 I picked up. After removing the rear mount it was clear that some of the lubricant had migrated and was causing drag on the aperture mechanism. Cleaned it off using a bunch of q-tips and some naptha now they work like new, among the best $6 on supplies I've spent in a long time. I haven't had to do that with any of my old screw mount lenses so I'm not sure of the procedure on them but I would imagine it wouldn't be any more difficult. Hopefully it is just in the mechanism and not the blades as I personally wouldn't want to clean those.

09-02-2021, 11:05 AM   #5
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mmmm...hard to say. I've had lots of old lenses with sticky apertures, dozens. But I don't think any of them had a problem with the aperture ring or pin themselves being sluggish, so if those really are stiff seems like a bigger problem, or something unique to that model maybe when the gunk migrates.
09-05-2021, 02:58 PM   #6
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Super Takumar 24mm/f3.5 sticky diaphragm: Help!

Ok, I am trying to get myself into trouble in accessing the diaphragm blades/mechanism of a ST24/3.5 to remedy their slowness in reopening. I've removed some of the back parts of the lens and am not sure what's next. See attached image. I did removed the three screws and that did not seem to do much. Can someone tell me what's next to remove? Thanks in advance.
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09-05-2021, 03:09 PM   #7
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If I remember correctly, the diap cup comes out of the front not the rear.


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09-05-2021, 03:40 PM   #8
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QuoteOriginally posted by MikeMcE Quote
If I remember correctly, the diap cup comes out of the front not the rear.


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hmm...I've seemed to have now gotten information now that says it's accessible from both sides!
09-13-2021, 05:41 PM   #9
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OK, I just pick up a second 24mm/f3.5 except this one is a Super-Multi-Coated Takumar and it also has a diaphragm that doesn't return open as fast as it should. It's more usable than the older Super Takumar 24/3.5 that a got a month ago. Anyone suggest who does CLA on Takumar lenses these days?
09-13-2021, 06:02 PM - 1 Like   #10
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Look up Don Goldberg (DAG repair)
Heís an old compatriot and should do


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09-14-2021, 06:11 PM   #11
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FYI: I contacted Don at DAG and he's currently very busy repairing Leica only for now.
09-14-2021, 08:08 PM   #12
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I think Eric Hendrickson still works on Takumars - pentaxs.com
I've also heard good things about Advance up in Oregon.
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