Sticky blades on 135mm f/3.5 Super Takumar

[Tony-S]

M42 mount. I have the rear element removed and have applied quite a bit of lighter fluid but the blades will not open when I release the pin. The seem to close down just fine, only reopening is a problem. Could it involve the armature inside the lens?

 

[John Koehrer]

Yes but you may have to repeat the flush several times. The lube doesn't just get on the blades but also the inside of the housing.

The proper way to do it is remove the housing from the lens, remove the blades, and clean both in an ultrasonic cleaner. Second choice, Naptha and Q-tips.
The trick is getting it all back together correctly and adjusting the aperture. The housing will rotate and the smallest aperture is measured and set to the original size. **You did measure it didn't you?**

 

[Tony-S]

Thanks - I have them working again. The return is a bit sluggish, so I'll continue with the naptha to see if I can improve it.

 

[paul ron]

I had the same problem with that lens n found it to be the preview/autostop down mechanism not the blades (unless you actually see oil on your blades). Look from the top n see the arms that move the iris n shutter?.. that is gunked up n needs to be cleaned. I did mine n all is well again.

.

 

[Tony-S]

What did you clean them with and did they need lubed after you were done?

 

[paul ron]

I use white gas (Coleman liquid camping stove fuel), it evaporates fster than lighter fluid. And no lube, left it dry.