Duct-tape the lens? :)

[Zang]

Hi all,

I am working on an FD 135mm with bad oil on aperture leaves issue. It turned out the inner helicoid is incorporated with the optical assembly and there are two cut-out openings on both side of the assembly as shown in the picture. Those are an easy path for oil to get to the aperture. As those openings serve no functional purpose as I can see, I am thinking about sealing them with a duct tape or gluing them with some thin foil. Do you think that will work or should I just leave them alone and put a minimal amount of grease to the helicoid?

Cheers,
Zang

[Nasos Kosmas]

or should I just leave them alone and put a minimal amount of grease to the helicoid?
Zang

Just that 

[Zang]

Just that 

Ok, I did that

[Zang]

The amount of oil on the aperture leaves suggests someone poured oil into the lens! I don't think grease turns into oil over time. How do you think?

[Gone]

Grease is basically oil mixed with soap, so yes it can break down over time, especially if the lens is exposed to high temperatures.

[Hugh_3170]

The original lubricant used in the Nikon 55mm f/2.8 AiS Micro Lens is a case in point - the grease initially used did in fact break down and its oily decomposition led to the aperture leaves of thousands of copies of this lens being affected.  So yes, certain types of grease do turn into oil over time.  Sorry.

The amount of oil on the aperture leaves suggests someone poured oil into the lens! I don't think grease turns into oil over time. How do you think?

[Zang]

Oh jeez... thanks guys.

[Erik Lund]

Aperture blades are not lubricated.
However parts in the vicinity of the aperture blades that are lubricated can spill lubricant, this is the case of for instance the Micro Nikkor55mm f/2.8 Ais at least some of the production batches