Repairing stuck aperture on a Asahi Super-Multi-Coated Takumar 135mm F3.5 lens.
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- čas přidán 22. 08. 2022
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Repairing stuck aperture on a Asahi Optical Co. (Pentax) Super-Multi-Coated Takumar 135mm F3.5 lens (m42).
Here we have a beautiful condition S-M-C Takumar 135mm F3.5 lens. It has one major flaw. The aperture does not stop down. Let's fix it.
FR EP86
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I've fixed a few sticky irises, but this one would have defeated me without this video. Thank you FR.
Thanks. I just won an 8 element Takumar 50/1.4 in excellent condition at a good price just because this same issue. It's not exactly the same lens but I got the idea and inspiration from you.
Thanks for sharing
Nice tutorial, thanks mate 👍
My old boss used to say, "If you never make a mistake, you're not working hard enough".
Stay safe.Peace
Do the parts go back together dry or they need a new form of some kind of lubrication? Thank you so much.
Yes, dry.
Is it necessary to remove the focusing parts to access the aperture assembly? I have a 135mm with the same issue and I was hoping to just approach the aperture assembly from the back end without stressing over the focusing helicoid.
Depends on the make and model.
@@FocalReduced oh sorry, I should have stated it more plainly. I have a 1971-ish Super-Multi-Coated Takumar 1:3.5/135 mm which I think is the same as your example.
In that case, yes you would need to remove the focus ring, but the helicoid can stay in place. As long as you don't turn the helicoid during the repair, you will have no issues with focusing.
I see, thank you! But that begs the question, how do you keep from turning the helicoid inadvertently? Seems a tricky thing to do especially when pulling things off and putting back on. Should I mark the barrel somehow?
I've generally found that taking the optical elements out from the front is the easiest way. (Canon SLR lenses are a good example.) On this lens I don't think there's a choice. The iris assembly is held by three screws that you might be able to get to from the back, but then the assembly has to be pushed out toward the front of the lens. From this and all the glued-in machine screws I found in my example, I doubt Asahi envisioned anyone ever disassembling this lens down to the iris blades.
What tools do you use and where can I buy them? Great video btw! Really helpful!
The tools can be bought online. We recommend not cheaping out on tools. We have had a few screwdrivers break and scatch the lens body. JIS screwdrivers are a must. There are many types of lens spanners. The one we use are not the greatest. The metal is somewhat weak and has bent a few times. We have repaired it many times with an anvil and hammer.
why not drop the whole assembly in a solvent to clean the oil or ultrasonic cleaner?
There is no way to confirm that all the oil has been removed without disassembly.