Fastest Tool to clear yellowed Thorium lenses

[fates]

Hmm that serial should be in the range, and it should work. Unless the lamp now ships with a non-UV bulb in it?

How yellow... er, monkey sh*t brown is your lens currently? Some lenses will cure faster than others. Are you seeing no progress at all? Are you getting the head of the lamp right up against the glass?

 

[Gabriel M.A.]

the IDIOT that smashed the thorium lens- let's hope he did not ingest any of the particles as it will destroy your stomach lining.

It's natural selection vs. the "who cares!" crowd. 😉

 

[unixrevolution]

the IDIOT that smashed the thorium lens- let's hope he did not ingest any of the particles as it will destroy your stomach lining.

Given what he did to that poor defenseless Takumar, I'm hoping he did ingest just a little. Karmic balance.

 

[fates]

Did anyone ever contact that guy and ask him to update his site? Dangerous to encourage kids to do this... by which I mean, ruining perfectly good Takumars.

 

[ampguy]

besides the Rokkor and Takumars as mentioned above, the fast Pen 42/1.2 (but not the 38/1.8), Nikkor 50 HC (maybe just some?) seem to have yellowing issues over time.

 

[former member]

The Nikkor-HC 50/2 - probably the Canadian Balsam yellowed, not from use of Thorium. Thorium is a Heavy Element- did not realize it was element 90 until Nikki did her homework tonight.

I love Heavy Metal.

 

[ampguy]

Thanks Brian

Thanks Brian

You are probably right, I got some info. from the posting here:

http://forum.getdpi.com/forum/showthread.php?t=18549&page=5

(way down on post # 245)

where the tester kept the white balance constant. Of course, his sample # is small, but I have heard of some Pens and of course the Takumars having Thorium elements, as well as very early Crons, etc.

The Nikkor-HC 50/2 - probably the Canadian Balsam yellowed, not from use of Thorium. Thorium is a Heavy Element- did not realize it was element 90 until Nikki did her homework tonight.

I love Heavy Metal.

 

[former member]

My Thorium Summicron is on it's way back from Focalpoint. I had the front surface polished and recoated. I will see how it compares with the later version.

I am still not comfortable putting a Hot-Glass lens on a Digital Camera. Maybe I'll take the lens off of an old Digital, put the Thorium lens over the sensor, and see if damage occurs.

 

[ampguy]

I'm with you Brian

I'm with you Brian

After testing a lot of lenses and old stuff around with a geiger counter, I'm not into radioactive lenses at all these days. First instincts are to hold them up to the eyes or leave out, and very close, some of these are still pretty hot, and will be for awhile.

My Thorium Summicron is on it's way back from Focalpoint. I had the front surface polished and recoated. I will see how it compares with the later version.

I am still not comfortable putting a Hot-Glass lens on a Digital Camera. Maybe I'll take the lens off of an old Digital, put the Thorium lens over the sensor, and see if damage occurs.

 

[rxmd]

My Thorium Summicron is on it's way back from Focalpoint.

The real question is - does the thorium make it a Summicron 90?

 

[michel v]

Hmm that serial should be in the range, and it should work. Unless the lamp now ships with a non-UV bulb in it?

How yellow... er, monkey sh*t brown is your lens currently? Some lenses will cure faster than others. Are you seeing no progress at all? Are you getting the head of the lamp right up against the glass?

Just checked on several localized Ikea websites. The only difference is the item number for this lamp, but it seems to only be there for regions (ie. same item for US & Can, and the same for all Europe). The only possibility of difference left would be European regulations forcing Ikea to use a different LED.

As for my lens, its yellow is similar to that exhibited by yours after 5 hours of bleaching.
And I did not put the lamp right against the frontal element of the lens, but 10 centimetres (4 inches) away, as I tried to bleach two lenses at the same time. Does this make a big difference?

 

[fates]

I would get the tip of the light right against the front element (don't rub it around, be careful) , leave for a day then switch to the rear element. Having such distance may be your problem... that and do one lens at a time.

 

[Uncle Fester]

Sorry, but for the life of me I can't understand why people would want to destroy the yellow coating on these lenses.

Yes, they are slightly radioactive, but they aren't about to produce three headed fish or make you glow in the dark. They are also totally unique in belonging to a time and place, and this is of value to many people. Also, the yellow itself adds a certain unique dimensionality to the image.

If you don't want the yellow, buy some other lens, but why destroy the rare existing ones?

Phil, most owners of the yellowed lenses do not think that the discoloration is a good thing. When these lenses were new, the glass was quite clear. When I bought my Takumars, used on ebay, I was unaware that certain lenses had a tendency to turn yellow and was very disappointed with the yellowed lenses. As a result, I have almost never used these lenses. Most people who are bleaching the yellow out of the lens are doing so to restore their lens back to its original state.


I now have, thanks to the OP, an inexpensive and efficient way of salvaging lenses that were previously not usable for me.

 

[Uncle Fester]

Hi all, just wanted to share the absolute fastest way I have found to clear up the yellowing of lenses due to rare earth content. I've cleaned up several Takumars and now a 50/2 Wetzlar rigid 'Cron with this lamp. After witnessing the speed in which it just cleaned up this Leica beauty from 1970, I was compelled to share this technique. For whatever reasons, it is able to clear up the yellowing of lens FAST. Like in all of 24 hours. Not a week of sitting in the windowsill trying to harness the sun.


So here's the secret tool.


The JANSJÖ work lamp from Ikea. Item number 101.287.34
It's an LED unit, but evidently puts out a highly focused beam of UV light that you can bend down right into the barrel of your lens. Seriously this thing works awesome. I've tried other UV bulbs to some good results but still those take days to undo the yellowing of decades of the radioactive breakdown. This lamp will cure it overnight. 2 nights, and you're back to like new.


Hope this is helpful to someone... other than Ikea's lamp sales.

Thanks for posting this, I have two yellowed Takumars, 50mm and 35mm that I can now clean up and use.

Mike

 

[Seele]

Phil, most owners of the yellowed lenses do not think that the discoloration is a good thing. When these lenses were new, the glass was quite clear. When I bought my Takumars, used on ebay, I was unaware that certain lenses had a tendency to turn yellow and was very disappointed with the yellowed lenses. As a result, I have almost never used these lenses. Most people who are bleaching the yellow out of the lens are doing so to restore their lens back to its original state.


I now have, thanks to the OP, an inexpensive and efficient way of salvaging lenses that were previously not usable for me.

Zathros,

To my mind, it seems that Phil believed the yellow tint in the glass was an original feature of a lens, as intended by the designer, so that an attempt to remove it would be making it non-original.

 

[Uncle Fester]

Zathros,

To my mind, it seems that Phil believed the yellow tint in the glass was an original feature of a lens, as intended by the designer, so that an attempt to remove it would be making it non-original.

True,

But after several other members explained why they would bleach the lens, he still insists that one should not bleach out the yellow, saying that they should get another lens instead.

I am interested in using a lens that functions as its designer intended, not in preserving, as Phil calls it, a "historical oddity". When these lenses were designed, the designers never intended for them to turn yellow after a few decades. This is an unintended side effect of the thoriated glass used in some designs. The designers were using the rare-earth glass because it allowed them to design fast, highly corrected lenses with the technology of the day.

I own two of the affected Takumars, a 50mm f1.4 Super Takumar and a 35mm f2.0 Super Takumar that I bought used on ebay a few years ago. At the time, I was unaware of the tendency of these particular Takumars to turn yellow with age. When I received the lenses, I was disappointed with them, but kept them because I felt that the sellers were not trying to rip me off. Since I was shooting a lot more color back then, I did not find these yellowed lenses very useful. I also did not like looking through the viewfinder with these lenses on the camera. I made do with slower lenses.

When I found out that this yellowing was reversible with exposure to UV radiation, I decided to try it at some point in time.

I consider the bleaching with UV light to be an act of restoration, not alteration. I believe that my lenses will finally perform as Pentax intended them too, once again, after I give them the UV treatment. I never got around to doing this before, since I was not comfortable with leaving the lens in the window for a few weeks while waiting for the sun to do its job. I feel that the OP's method is an elegant solution to the problem. Cheap too!

To quote Brian Sweeney, in post #12 of this thread;

"As far as restoring lenses and cameras to their original and intended working condition, that is the point of camera repair. Radiation Damage in glass is an undesirable side-effect of the materials chosen for their construction and restoring them to their intended state is always desirable."

I think Phil just doesn't get it. His comments seem rather silly to me.

 

[sevo]

The only possibility of difference left would be European regulations forcing Ikea to use a different LED.

So far, LEDs are only capable of putting out very, very near visible UV - and white light (fluorescent) LEDs emit pretty much nothing invisible at all. So there is nothing that could be regulated there. It is more likely that Ikea, cheapskates as they are, use low-grade LEDs of poor colour consistency, where some will be leaking blue from the LED proper while others have too much of a fluorescent cover and a corresponding excessive yellow tint. Something like that would be perfectly in line with the notoriously poor colour rendering from Ikea CFL lamps.

 

[michel v]

I never got around to doing this before, since I was not comfortable with leaving the lens in the window for a few weeks while waiting for the sun to do its job.

That's what I first did with my 50mm. The problem is, at that time the sun only shone for a day, then I forgot about it, then rain happened, then I remembered I had a lens on the window!
To my surprise, the lens still works. I think rain might have damaged the coating though, and that in some years fungus might appear… But oh well, still trying to bleach it now. 🙂

 

[jplbound]

Great idea

Great idea

Hi all, just wanted to share the absolute fastest way I have found to clear up the yellowing of lenses due to rare earth content. I've cleaned up several Takumars and now a 50/2 Wetzlar rigid 'Cron with this lamp. After witnessing the speed in which it just cleaned up this Leica beauty from 1970, I was compelled to share this technique. For whatever reasons, it is able to clear up the yellowing of lens FAST. Like in all of 24 hours. Not a week of sitting in the windowsill trying to harness the sun.


So here's the secret tool.


The JANSJÖ work lamp from Ikea. Item number 101.287.34
It's an LED unit, but evidently puts out a highly focused beam of UV light that you can bend down right into the barrel of your lens. Seriously this thing works awesome. I've tried other UV bulbs to some good results but still those take days to undo the yellowing of decades of the radioactive breakdown. This lamp will cure it overnight. 2 nights, and you're back to like new.


Hope this is helpful to someone... other than Ikea's lamp sales.

The nearest Ikea is 250 miles away!!! They do not offer this online. Strike two; I guess I will have to use a black light.😡

 

[KoNickon]

Someone above mentioned the Rokkor 28/2.5MC as having the discoloration (and I like the suggestion about using a color correction filter for it). I have that same lens and discoloration, but someone else (Brian?) indicated that discoloration is likely due to the lens cement. I have a Nikkor 35/1.4 that's discolored as well. I infer that this IKEA lens won't work on the balsam, correct? Too bad if that's so, since I figure having someone like Focal Point decement and recement a lens would be big bucks.