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F16sunshyn
Tinkerer
Username: F16sunshyn
Post Number: 3
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 06, 2007 - 09:13 am: | 
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I bit the bullet last week and overspent for a Yashinon 55 1.2 M42 mount. It is like new and maybe unused. The only issue is it seems to have a bit of a yellow cast when I look thrue the viewfinder. I have only shot B&W so far so it is hard to see effect.The coatings kind of look yellow to me with these lenses. I read about someone putting an old takumar lens in a window sill for a week to solve similar issues. It sound like hokus-pokus to me. But photography and cameras are all about magic right? Does anyone have any feedback,experience, or general science about this one? |
Berks
Tinkerer
Username: Berks
Post Number: 3
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, June 06, 2007 - 12:29 pm: |
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I have tried that trick with a yellowed Yashinon DS-M 50/1.7 and it worked very well. You can put a sheet of tin foil between the lens cap and front element to increase the effect. Then just remove the rear cap and put the lens somewhere where it gets direct sunlight. You may need to re-position the lens as the sun moves.
For your lens maybe it is better to put the tin foil at the back and expose the lens to the sun from the front. The tin foil increases the effect by exposing the glass for the second time by reflected rays. You also make sure you do not set something on fire.
My lens cleared up in 2-3 days. I do not know how long it takes for a 55/1.2. Depends also on how yellow it is. |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 294
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 07, 2007 - 03:29 am: |
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Do you see the yellow cast when you look through the lens (not on the camera) at a brightly sunlit sheet of white paper? If so, it is not the coatings, it's discoloration of the glass. I have not done it myself (I've never had one of these lenses) but I have discussed the windowsill fix first hand with (I believe) one of the first guys to do experiment with it a few years back. As I recall the exchange, it worked very well and took about a week in the window in a semitropical location (farther north might take longer, but this is at least a good time of year for it). He wrapped the barrel in aluminum foil, mainly just to reduce the amount of heating of the lens from the sun so he wouldn't have to go right in and clean the focus helical grease out of the diaphragm. |
Bcostin
Tinkerer
Username: Bcostin
Post Number: 2
Registered: 09-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 08, 2007 - 05:43 pm: |
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The windowsill method definitely helps. I've used it on badly yellowed Takumar 55/1.4 and a Canon 58/1.2. I left the on the sill, upside down, with top capped in aluminum foil.
It took about 2 weeks of Maryland sunshine to see a difference, but this was in fall when the sunlight was fairly feeble. And I had to use a less bright windowsill that was inaccessible to our cats (they ruthlessly remove any foreign objects on "their" windowsills.) |
Petercat
Tinkerer
Username: Petercat
Post Number: 9
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 09, 2007 - 02:25 pm: |
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I wonder if a florescent or an ultraviolet lamp would work as well? No fire hazard, no moving the lens, easy to cat-proof (unless yours have opposable thumbs). Would someone try this and let us know? |
Alchemy
Tinkerer
Username: Alchemy
Post Number: 1
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, June 11, 2007 - 02:48 pm: |
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A UV sun lamp will work. I cleared the yellow tint from a couple of aero ektars and a tth enlarger lens with a small florescent tanning lamp. It took about two weeks though. |
Docman
Tinkerer
Username: Docman
Post Number: 12
Registered: 03-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, June 12, 2007 - 12:06 pm: |
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yeap. UV lamps works like a charm. Beware of skin burns & intense heat.
It will discolour any fabrics also.
Careful. |
F16sunshyn
Tinkerer
Username: F16sunshyn
Post Number: 10
Registered: 05-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 17, 2007 - 06:20 pm: |
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So yes this does work quite well yellow cast is gone. I happened to have the lens in a window sill during a dinner party. One of the fellows noticed it and asked me if I was killing fungus. I explained what I was doing. He proceeds to describe using this same method to destroy fungus that he discovered in early stages many years previous. Makes sense to me. I am sure that uv light would do the same job. The mellow but steady amount of heat from our NW sun probably would aid as well and make window a better option. Late stage or foci anywhere but very edges would not be helped of course. The only fungus I have ever personally encountered has been on very edges of front element interior. It was before my years as a tinkerer and I paid for a CLA to remedy. This certainly would save that trouble. |
