Oil on aperture blades... bad?

[bellyface]

Just got 2 lenses, LTM, J8 & J12, came with oli on the blades... should I be worried? Just purchased them here on the forum. Guess, no big deal with it not moving when I take a shot, but should I worry about it eventually getting to the optics?

[fidget]

Some mixed opinions on this. Seems to happen when the wrong type of grease is used to relube the focusing thread.
Read some more here: http://www.rangefinderforum.com/foru...t=oil+aperture

[indridi]

hmm, I too would be interested in knowing how big an issue this is. Just got my fed 2 (I _do_ like my fed 5, but the fed 2 just feels soooo good) and the Industar 26M has oil on the blades.
It actually has dust allover and is in an overall crappy condition, and I didn't by the camera for the lens anyway, so I was going to experiment with it by taking it apart and relubing it before I try such an operation on my very nice I61L/D, but I would still want to know if the oil will in any way affect image quality.

regards
Indriði

-edit-
fidged beat me to it - thanks

[Kim Coxon]

In itself, oil on the blades of a preset lens such as an RF lens is no problem mechanically though it is usually a killer on auto lenses ie SLR ones. I wouldn't worry about a small amount of oil though I would remove it if servicing the lens. If it is needed to hold the blades so that the apeture doesn't move, then I would sort the problem in the control ring for the aperture. (usually caused because the grease in there has solidified.) I would worry if there was a reasonable amount. I have heard of reports that it has caused internal reflections though I haven't experienced it myself. However, the oils has migrated there usually coming from the yak spit grease breaking down. If oil is creeping around the lens in any appreciable quantity, there is a risk of it getting on the glass which would affect the optical performance.

Generally speaking, it is quite easy to clean and relube the FSU lenses so I would always tend to do it.

Kim

[bellyface]

Can anyone recommend a take-apart lens diagrams on the LTM jupiters?

[varjag]

Oil can also be the source of haze (through evaporation and spreading), and provide food for fungus.

[Kim Coxon]

Try my website here. http://www.pentax-manuals.com/repairs.htm

Kim

Originally Posted by bellyface

Can anyone recommend a take-apart lens diagrams on the LTM jupiters?

[tedwhite]

I think Kim's post pretty wel explains it. I have a 1956 Canon 50/1.8 in LTM for my Bessa R. Got it from Frank S. It has some visible oil on the blades but the glass is clean and clear and it works just fine. As Kim said, it would be a killer on an AF lens or I suspect also on Super Takumar M42 lenses with the pin for use on Spotmatics.

But for RF preset lenses I don't see it as a problem unless migration occurs.

Ted

[steamer]

I've had a couple of things happen with the oil on the blades. On a contessa the oil seemed to have vaporized on the glass and made colors in photos all strange, and images were smeary, 2 on a Zeiss Opton coated 85 f2 lens, the oil on the blades would cause hellacious flare in backlit situations and in bright sunlight.