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12-01-2008, 04:37 AM   #16
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Me too

Thanks for the pictures. It's making a real difference.

03-06-2009, 07:05 AM   #17
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God Darn Winter
mine was almost 5 weeks in a window so that light will hit it in the morning at least, but it was not enough.... or double glass windows block all the UV needed?

his brother was clean in 2 weeks in the NC summer, which is a good 10-15 degrees souther than here
03-06-2009, 07:15 AM   #18
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QuoteOriginally posted by titrisol Quote
or double glass windows block all the UV needed?
that would most definetly hinder the process.
03-06-2009, 10:09 AM   #19

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Note that window glass blocks most of UV light. Leaving the lens behind the glass will take significantly more time.

It took 2 summer days (No. CA) to clear my Super Takumar 50mm 1.4, left outside. I imagined it would take about 2 weeks if the lens had been behind a window.

03-06-2009, 05:40 PM   #20
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Takumars are superb glass, and beautifully made barrels and helicoids. Though be warned..some of them are radioactive! the faster ones are usually the culprit I.E Super Takumar 50mm f/1.4, Super Takumar 35mm f/2 - those two are the worst. I think they used radioactive Thorium salts to raise the refractive index of the glass to make such fast lenses, And what it does is it causes the lenses coatings to go yellow, and in some cases cloud over completely. You can spot lenses that have suffered from this just by looking through them. As an experiment I took a lens to the ultraviolet imaging centre in Adelaide University and they bleached the lenses with UV light... a concentrated blast of ultraviolet light for about 4 seconds, and now that lens is crystal clear...I haven't had time to test that lens yet, I hope that didn't do anything to the coatings, the lens was quite warm after that treatment!

An interesting note, I have never seen a radioactive lens with fungus in it. also for the men on this site, don't keep a radioactive lens in your pocket for too long.

Sample image: Pentax 50mm f/1.4 Super Takumar (made C1964)

Last edited by Digitalis; 04-07-2009 at 06:05 PM.

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