Help with oil on blades....

[Pascal]

Can someone please explain why some sellers put down "no oil on blades" when describing the condition of an old lens.
What if there is oil on the aperture blades.... what's the worst that can happen...
If the lens is a fully manual focus lens, does it really matter.
What if the lens is a manual focus - auto aperture lens. Will it impact operation of the lens on it's native system or will it have any impact to operation of the aperture blades when used with an adapter on a digital SLR ?


What about fungus on a lens... and it's inside... what's the worst case scenario... lets say a lens has a little bit of the web pattern typical of fungus on one end of the lens.... how does it affect the performance of the lens... can it do any damage to a digital or film SLR ?

Any opinions/suggestions appreciated.

 

[Pascal]

Thank you. That helps.

 

[Spyderman]

On SLR lenses oil can cause the blades to be slow, or to stick.

On RF lenses this is not a problem, but as has been said before: it can evaporate causing haze, it can get to the glass. However if there is only light amount of oil, and it's some modern type of oil, I wouldn't be affraid. Most FSU lenses I've seen have oil on blades.

I still have a J-3, which had the blades badly scratch each other at small f-stops. I put a tiny drop of oil on them intentionally. No scratching anymore, and the aperture ring moves smoother.