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09-03-2015, 03:02 PM   #1
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Tak 85 1.9 help needed

So, I have a Tak 85 1.9 with an aperture that does not close. When put in A there is a bit of resistance on the pin, but no movement. It looks as if it has never been used, so maybe I can just disassemble and clean aperture mech (how?) Also, while i have it apart, how best to clean the glass? There seems to be a tiny bit of fungus. I should probably send it to Eric.... but as a diy-er I can't help diy-ing. Thanks guys.

09-03-2015, 04:00 PM   #2
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Mine is a pretty old Super-Takumar, with the old-style lettering and six-digit serial. It came apart like a typical Takumar prime. Mine was nearly exactly like a 55/1.8. Here is what it looks like with the trim ring off.



Mine has slotted screws. I would expect the older ones use all slotted screws, maybe the S-M-C ones use JIS. You can look up any of the Takumar several strip-down articles to see what you might have to do. You should be able to avoid unscrewing the focus helix. I would consider taking off the focus ring, trim and aperture rings because they gather a lot of crud over 45-50 years. So depending on where your fungus is, you might end up removing all the other parts except for that.
09-03-2015, 05:52 PM - 1 Like   #3
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The aperture blades are most likely gummed up with old helical grease. Flushing the blades with naphtha, swabbing away the
thinned grease and repeatedly activating the aperture should get the blades working and snappy again.
09-03-2015, 09:07 PM   #4
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Thanks, I assume I have to disassemble the lens and remove the blades to flush with naptha?

09-04-2015, 06:18 AM   #5
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Easy lens to pull apart. Have you got the right gear?
09-04-2015, 07:36 AM   #6
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What would I need? I also build/repair vintage tube microphones so I have some tools like small screwdrivers, tiny needlenose pliers, nothing lens-specific.
09-04-2015, 09:44 AM - 1 Like   #7
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QuoteOriginally posted by ChatMechant Quote
What would I need? I also build/repair vintage tube microphones so I have some tools like small screwdrivers, tiny needlenose pliers, nothing lens-specific.
An old toothbrush
A friction tool to get the "name" ring off
Screwdrivers for slotted screws like in my photo
Very small slotted screwdriver for "grub" screws like in the ring with depth of field markings
Maybe a lens spanner or improvised lens spanner
Solvents and fungus killing stuff.

This guide is for a very similar lens: https://www.pentaxforums.com/forums/114-maintenance-repair-articles/217082-ta...egreasing.html When you get to step 3 in that guide, you can see a few slots for a lens spanner around the front element. Use the outermost slots to unscrew the whole front group. That gives you access to the top of the aperture blades.

At this point you have to decide how much more disassembly you need to do to free the blades. It shouldn't be that difficult to remove each blade and lean them all. I know I was able to figure it out myself in 2006 when I did mine, but can't remember exactly how it goes. Focus the lens so the front barrel protrudes (not so far that it falls out) and look for grub screws on the outside of that barrel. Reassembling them needs a little patience but there are only six. The worst-case scenario is not oil, which cleans up, but rust sticking the blades together. They are so thin that rust can make holes or deform them. Mine had just a couple of rust spots which scraped off and haven't recurred.

Step 9 in that guide is not necessary if your focusing ring works OK.
09-04-2015, 09:47 AM - 1 Like   #8
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By yours truly:

JB Media | S-M-C Takumar 1.9 85mm Refurbish

The S-M-C version was a bit unusual in that it was not updated for stop down metering like most other models. That means that the mechanicals are the same as the earlier Takumar version.


Last edited by jbondo; 09-04-2015 at 09:57 AM.
09-04-2015, 02:33 PM   #9
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The above two posts have well outlined your approach - give it a go, not much to fear and when practiced you will probably start buying lenses needing the clean.
09-04-2015, 03:34 PM   #10
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QuoteOriginally posted by jbondo Quote
By yours truly:

JB Media | S-M-C Takumar 1.9 85mm Refurbish

The S-M-C version was a bit unusual in that it was not updated for stop down metering like most other models. That means that the mechanicals are the same as the earlier Takumar version.
Thank-you so much for putting out that exhaustive step-by step. I read through the whole thing. It looks fun/nerve-wracking. Actually it scared me a little into thinking maybe I should not mess with the helicoid section and just soak the whole aperture mechanism in naptha.
09-04-2015, 03:54 PM   #11
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QuoteOriginally posted by ChatMechant Quote
ust soak the whole aperture mechanism in naptha
I've tried that on a few in the past without very satisfactory results. It can help, but it's really hard to get all the contaminants out without dissasembly. If you do soak it, be sure and change out the soak with fresh clean solution a couple of times - otherwise you'll end up with a film of contaminants left over all the soak surfaces.
09-05-2015, 07:19 AM   #12
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Thanks for that tip, I should probably just do it right the first time, not the second.
09-08-2015, 03:01 AM   #13
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Don't stress about disassembly - take it slow and document the process with photos. All good and lots of fun. You get to learn lots about your instrument in the process.

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