Re: 90mm Tele-Elmarit lubrication trouble

["C.M. Fortunko" <fortunko@boulder.nist.gov>]

I have several older lenses, but not the Tele-Elmarit. They do not show
signs of internal coating. I have found some grease on the outer surfaces on
some of the lenses when I bought them. However, this was easily cleaned off.

I find this conversation most amazing. I wonder if others can shed some
light on this important subject.

Chris

At 08:28 PM 7/22/96 -0700, you wrote:
>I had an interesting conversation with Don Chatterton this morning. I 
>inquired about a used, late model, 90mm Tele-Elmarit for my M6. With a 
>concerned tone in his voice he said he might have some but that he wasn't 
>sure what condition they were in. As he rooted around in his collection, 
>he explained that the lubrication used in the lenses was sperm whale oil. 
>The sperm whale oil evaporates when it's warm and forms an occluding film 
>on the interior lens surfaces over time. Since the rear element is glued 
>in place on the Tele-Elmarit the interior surface cannot not be accessed 
>for cleaning (at least not without destroying the lens).
>
>He said that he is able to sell only one (1) in four (4) or five (5) of 
>the lenses he gets. The rest he discards due to this damage.
>
>He had a lens that did not show the evaporation damage. I asked if the 
>lens would be useable five years down the road, and he was not 
>encouraging.
>
>According to him, the oil vaporization problem is not limited to the 
>Tele-Elmarit, but other older lenses have elements that can be cleaned.
>
>In conclusion he recommended a new or recent (used) lens since Leica has 
>switched to synthetic lubricants that do not vaporize nearly as easily. 
>He also felt that the optical quality of the new 90mm lenses was clearly 
>superior to the Tele-Elmarit and the size difference was not great.
>
>I am now considering a new 90/2.8 for this reason.
>
>I'm returning to the list after a two month absence, so if these issues 
>have been covered recently I apologize for the redundance.
>
>-Charlie
>
>-------------------------------------------            
>            Charles E. Dunlap
>            Earth Sciences Dept.
>            University of Calif.
>            Santa Cruz, CA 95064
>
>          cdunlap@earthsci.ucsc.edu
>408-459-5228 (office)    408-459-3074 (FAX)
>-------------------------------------------
>
>
>