uncoated lens surface cleaning
"Cheesehead" wrote in message ... I picked up an old uncoated Tele Xenar 360/5.5 today. The front cell, inside surface needs cleaning. What chemicals should I use to clean it? It looks like some condensation was let sit for years. It might require some serious buffing! The last picture here shows the problem. http://www.apug.org/forums/forum379/...tfit-more.html Whatever you do don't buff or scrub it! Most of this sort of haze will come off with ordinary lens cleaner. I suggest "streak-free" glass cleaner. Other good cleaners are dry isopropyl alcohol (isopropanol) and, if you are able to remove the elements, acetone. Acetone is a standard cleaner for lens assembly at the factory but will dissolve some paint so be carful. For oily deposits you can also try naphtha. Quite pure naphtha is available as Ronsonol lighter fluid. Haze inside lenses is very common. I don't know for certain what the source is but probaby either something from the lubricant in the shutter or something evoporated from the anti-reflection paint in the cells. If you find you have a mold of some sort a mild solution of bleach will help remove it but should be rinsed off thoroughly. Long standing mold or mildew can etch the glass. If the surface has been etched there is no fix but re-polishing the lens, provided the etching is not too deep. This is expensive and may be more than the lens is worth. I don't know how the Tele-Xenar is mounted but most lenses have either a retaining ring on the front or a threaded cap on the back. Retaining rings sometimes do not have slots or dots in them and must be removed by using a friction wrench. The are not hard to make but finding the right kind of sticky rubber may be difficult. Just to be clear, there is NO difference between cleaning a coated and an uncoated lens, both the same. Use a lint-free tissue. Kimwipes are fine. Use each wipe ONE TIME and discard it. Wet the wiper, not the lens, then drag the wiper across the surface and discard it. Use as many as you need to do the job. The reason is because a tissue or cloth, even a brush, can pick up particles of abrasive grit and when re-used scratch the surface. That is also why "buffing" or scrubbing is bad; only one bit if grit is enough to ruin a lens. Some here will tell you they have used the same bit of microfiber cloth for years and it never damaged a lens. I would ask to look at the lenses. -- Richard Knoppow Los Angeles, CA, USA |
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