50mm El Nikkor problem

[David Lingham]

I have a problem with a 50mm 4 element El Nikkor lens. I recently noticed what I can only describe as a “circle of frosting” that has a clear area within it. When I hold the lens up to a light and examine it at maximum aperture through a loupe, the “frosting” appears to be on an internal element. I normally work at two stops down (F8) which uses the clearer area of the lens, but I’m now wondering how long this has been there, and does anyone know what might have caused it. The lens still performs well, and is about 35yrs old.

 

[AlexG]

Does the frosting look a bit like calcium build up on a coffee pot? If so, I've had the same type of problem on ALL my older Pentax lenses. I suspect that the culprit is mold/fungus that has worked itself into the inner elements over time. On a camera lens, mold usually doesnt show up unless it's quite bad, but I've never had this problem on an enlarger lens so I wouldnt know myself.

Could you try a test print with the aperture wide open?

 

[Steve Roberts]

I have a slight haze inside a 50mm f2.8 EL Nikkor that is only visible if you look very carefully against a light source. I dismantled the lens to try to clean it but found the problem to be between two cemented elements and so left well alone. I continue to use the lens and whilst I don't have an identical lens to compare it to, I'm not aware of any problems in the finished prints when compared to prints made with other enlarging lenses I have. The haze on my lens is uniform rather than having a hole. I don't know how old the lens is as I bought it secondhand. I think that perhaps such problems are more irritating because of what we fear they might do than because of the reality of what they actually do!
Best wishes,
Steve

 

[David Lingham]

Thanks both. Alex yes it does look like frosting, so could well be fungus as you suggest. Steve, interesting that the same has happened to your lens. How old is yours?

 

[Steve Roberts]

Thanks both. Alex yes it does look like frosting, so could well be fungus as you suggest. Steve, interesting that the same has happened to your lens. How old is yours?

I don't know how old mine is, David, as I bought it secondhand, but if it's any guide it's the type before they started having illuminated f-stops (which I often wish I had).

Steve