clean dust inside lense

[Brian Heath]

I have a Schneider G-Claron 150mm lens which seems to have some dust inside the front lens element. Is it possible to clean it or is there a service anyone knows of that can clean it?

Thanks for any help

Brian

[Leonard Evens]

Unless there is a lot of dust there, you should leave it alone. If you want to clean it, send it to professionals like

www.skgrimes.com

[Ralph Barker]

Leonard's suggestion is sound advice. Depending on where the dust is located, however, you might be able to solve the problem yourself with minimal risk to the lens. Both the front and rear elements can be removed from the shutter, and carefully cleaned. They simply unscrew in the usual counter-clockwise direction. Beware of any spacing shims that might be present, however. If, however, dust has found its way between air-spaced elements in the front or rear assemblies, a good lens technician is the best/only solution.

As Leonard suggests, however, run a test with the lens to see if the dust is actually causing a problem. A spec or two often goes unnoticed by the image.

[Brian Heath]

thanks for the advice, i'll follow up. Here's one more question. When I looked at the lens with a magnifying glass it looks like crystals or a crystal formation on the inside of the front element. like a snowflake pattern but the lens has never fell or been handled roughly. Has anyone heard of this type of thing inside of a lens before. The external side has no sign of defect at all. I just shot with this lens this past summer and the shots show no sign of problems. I just shot some tests yesterday and will see if it shows in the prints and transparencies.

[Ralph Barker]

Older lenses sometimes suffer from either fungus eating at the cement that keeps the elements of the lens groups together, or from delamination, where the cement starts to fail. I personally haven't seen examples of either, however, so I'll leave it to someone who has to say whether either matches your description. The older glass will also have microscopic imperfections, but those, I believe, are usually tiny bubbles, not snowflake-like structures.

[Brian Heath]

I got my test b/w negs. and transparencies back today and none of them show any of the patterns on the lens itself, amazing!!!

there were some other info on the forum on schneider lens and the fungus issues on older glass. this one I bought in 1988, my first toyo 45C and lens. I guess I got my monies worth and then some. I'll test some more but it looks like the lens is still good.

Thanks for everything, especially the skgrimes link.