why do some old lenses show oil on the aperture blades? does that mean they where serviced by a non-leica repairsman? does it affect the picture quality?

-- stefan randlkofer (geesbert@yahoo.com), December 09, 2001

Answers

If this oil is truly copious semi-liquid lubricant, then it can lead to problems. I certain situations, such as heat, the oil can vaporize and condense on internal glass elements, which would cause optical degradation.

Many of my older lenses have the appearance of oil, but in reality it is simply the wear of repeated aperture blade movements, which makes the rubbed metal look shiny. If your lens actual has oil in it, I would have it cleaned and checked by a good service outfit.

-- Al Smith (smith58@msn.com), December 09, 2001.

Stefan:

I have never had this problem with Leica lenses. I did have it with one Nikon lens [50 mm f/2.8 macro]. I sent it back to Nikon two times for cleaning. When it developed the same problem a 3rd time, I started using it in the stop-down mode. A bigger problem with an SLR. Evidently, they couldn't fix it.

Art

-- Art (AKarr90975@aol.com), December 09, 2001.

Most often it's from the lube in the focusing mount spreadinging to the iris blades.

A sign that the lens needs a CLA.

Cheers!

-- Tony Oresteen (aoresteen@mindspring.com), December 10, 2001.

Hello Stephan

I recently bought a 35mm/f2 with some sign of use.

I too thought there was oil on the blades. But in fact it was a shiny scar left by the blades themselves.

To convince yourself, manipulate the blades in the light of a bright midday sun. On the lens, the most visible wear is at 5.6.

May be the lens was stored in a vibrating environment such as the floor mat of a car with no or little protection.

Regards.

-- Xavier d'Alfort (hot_billexf@hotmail.com), December 10, 2001.