回答: 尿黄尿黄的哦。。哈哈 由 perisherblue 于 2012-07-18 23:39

How to Cure Yellowing in Takumar 50mm f1.4 lenses. www.6park.com
Remove the lens cap and wrap the uncapped lens, except the rear element,
in aluminum foil and then set it on a windowsill that faces towards the sun. www.6park.com
Prop it up with something (like a rolled-up towel) so that it tilts in order
to get the most sunlight into it. Then go away and leave it. www.6park.com
A mild case takes about a week to ten days on a windowsill in California. www.6park.com
A severe one takes about a month. www.6park.com
The foil serves two functions. It reflects light off the lens body and thus reduces heat buildup that otherwise would occur due to the black finish on the lens and this could affect the lubrication inside the lens. www.6park.com
And by not capping the lens before wrapping it, light makes its way from the back of the lens and reflects back off the foil at the front of the lens, thus attacking the yellowing again. www.6park.com
This "sunlight cure" method has been successfully employed by a number of members of the Spotmatic group and many 50mm f1.4 lenses which were thought to be useless for colour photography have now been returned to active service with "water clear" glass. www.6park.com
Some others have reported good results in about three weeks using an
ultraviolet light source. www.6park.com
The yellowing problem affects the Model II 50mm f1.4 Super-Takumars and all
other 50mm f1.4 lens through to the K-mount series. www.6park.com
The older Model I 50/1.4 Super-Takumars, the 8-element ones (which can be
distinguished by the protruding element at the rear NOT having a protective ｍｅｔａl rim), do not turn yellow because they do not have the radioactive element, using an additional regular optical glass element to get higher refraction instead.