Filters to repair yellowing glass,

[iha]

Hi,
I have some lens that is comming more yellowing (Takumar, Tomioka, Minolta, and the last record Pancolar). I am trying to use UV lamp to reduce this problem. I heard somewhere that I can use MC or HMC 1B (maybe made by Hoya) to balance a color pictures, is it true? I just have got UV filtes, so if it is sure I will buy some ones.
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[Orio]

UV filters will not solve the problem. They might, actually, enhance it.
What would help is a purple filter - since they are not easy to find, a blueish filter similar to those used to photograph under tungsten light using daylight film can be used. You will have of course make experiment to find the best filter density.
But, in general, I am not much in favour of stacking filters to solve colour problems - I say stacking because the yellowing of coating can be considered the equivalent of a filter.
If you can not solve the problem by sun-tanning, my advice is to use, for sensible uses (like film), different and non-yellowed lenses, and to limit use of yellowed lenses to digital photography, where you can apply white balancing to raw files.

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[patrickh]

Orio Same difference, but you can also adjust WB in camera for RAW files on most DSLRs. Cant wait to see if UV light will save my Helios - I really would prefer to have a clear lens.


patrickh

[iha]

I know the PS can do a lot, just a question when I need a filter to protect a lens, I would like to buy that can be balance colour, not only UV.
By the way I am waiting for a result of UV lighting in next 3-4 days.
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[F16SUNSHINE]

Just my 2 cents. I have removed yellow successfully with both the sun and with a UV bulb light source. The Bulb method was done at my repair mans shop and only took one week. It was a 50watt (110v 60hz) tube style bulb. The thing creates ozone and is quite nasty for humans and other creatures to be around. The sun method took nearly 2 months to completely clear lens. The length of time it takes can vary depending on how radioactive the lens is and how yellow it has become. My lens was an old Yashinon and in really bad shape. The best way to expose the lens to the sun is to use some sort of reflective material. Wrap the lens in foil to protect from excess heat. If you direct the lens so light shines straight thru also put reflective material at the rear element. This will bounce the uv rays back thru the lens. Remove any uv or haze filters. These are designed to reduce uv and will slow the process. A month or two in a windowsill is not good for the front element. A clear protection filter is a must. If you don't have one a tight stretch of cellophane will do the job if heat does not become to high. It definitely works just be patient.

Wow I got kind of windy for just 2 cents

Andy

[iha]

Thanks, it sounds promising! I am still trying with UV lamp for some days more.
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