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Fastest Tool to clear yellowed Thorium lenses
Old 02-15-2011   #1
fates
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Fastest Tool to clear yellowed Thorium lenses

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 JANSJΦ 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.


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Old 02-16-2011   #2
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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?
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Old 02-16-2011   #3
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I thought this was the fastest way: http://web.aanet.com.au/bayling/repair.html
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Old 02-16-2011   #4
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Quote:
Originally Posted by phil.wright View Post
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?

The Yellowing of the glass is from radiation damage from the radioactive Thorium. It was not made into the glass, and is not a yellow coating. The lens performs much more naturally with it gone.

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.
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Old 02-16-2011   #5
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The Rigid Summicron does not use Thorium. The early Collapsible Summicrons, serial number under "About" 1050000 use it, and i have three of them.

The yellowing in a Rigid Summicron is from the Canadian Balsam turning yellow with time. I have never tried bleaching it out, please report the results with it.
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Old 02-16-2011   #6
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OK Brian I stand somewhat corrected about it not being a coating, yet the yellowing DOES give unique properties - if you want a lens to perform naturally, why buy an interesting lens like this and then take away the very thing that makes it interesting?
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Old 02-16-2011   #7
Brian Sweeney
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Have you ever used a Collapsible Summicron AFTER it has been bleached clear?

If you shoot just black and white, it is like having a yellow filter attached. So- you can always put a yellow filter on a lens and get the same result.

You have to bleach out the Thoriated Glass to get the filter off. It is well worth it, and you can always use a yellow filter for B&W.

I should add- I have one at Focalpoint now for polishing and getting a new front coating. It was opaque when I traded for it. A second was picked up in a trade for a Summitar and cash, because the owner wanted to shoot color. Picked up the third on a Leica IIIf, probably been on it since 1952.

For interesting: it is the low dispersion qualities of thoriated glass that make the lens interesting, at least to me. Not the radiation damage.

Last edited by Brian Sweeney : 02-16-2011 at 02:45.
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Old 02-16-2011   #8
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Quote:
Originally Posted by phil.wright View Post
OK Brian I stand somewhat corrected about it not being a coating, yet the yellowing DOES give unique properties - if you want a lens to perform naturally, why buy an interesting lens like this and then take away the very thing that makes it interesting?
Dear Phil,

Alternatively, why not take it back to the state it was in when it was new?

Taking your argument far further than you would, why repolish a scratched lens? If you think the scratches make it interesting, leave 'em; if not, why not restore it? And bear in mind that the restoration is fuly reversible. Just leave it for another few decades...

Cheers,

R.
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Old 02-16-2011   #9
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Quote:
Originally Posted by Brian Sweeney View Post
The Rigid Summicron does not use Thorium. The early Collapsible Summicrons, serial number under "About" 1050000 use it, and i have three of them.

The yellowing in a Rigid Summicron is from the Canadian Balsam turning yellow with time. I have never tried bleaching it out, please report the results with it.
Dear Brian,

No, surely it was Wetzlar balsam in those days...

(I don't do smileys, but those who like them can imagine one.)

Cheers,

R.
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Old 02-16-2011   #10
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But Brian my point is, that bleach it and an historical oddity is no more. If you don't want the yellow filter effect all the time, buy any other lens that does not have the Thorium thingy. The OP seems to be running a production line of "fixing" the unique properties out of these lenses - why doesn't he just buy lenses that don't have the "problem" (or unique attribute) in the first place.


And no, I have never used one. I have never used a collapsible Summicron at all.
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Old 02-16-2011   #11
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Quote:
Originally Posted by Roger Hicks View Post
Dear Phil,

Alternatively, why not take it back to the state it was in when it was new?

Taking your argument far further than you would, why repolish a scratched lens? If you think the scratches make it interesting, leave 'em; if not, why not restore it? And bear in mind that the restoration is fuly reversible. Just leave it for another few decades...

Cheers,

R.
Hi Roger,

Well, why buy a scratched lens if you don't want a scratched lens (unless you can't afford an unscratched one in which case you are going to have to pay more for it to be repaired blah blah).

Besides which, there are many scratched/unscratched lenses but, as I said, these are historical oddities that belong to a time and place.

I must admit that I didn't know the Thorium would re-zap the lenses over time but - why do it if you don't want THAT lens for its individual properties?
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Old 02-16-2011   #12
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I am buying one of these lamps for myself!

Much better than leaving in the Sun to cure. I have a Collapsible Summicron that was sunbleached, before I received it. The grease was like Tar, the focus was impossible. I relubed it. I switched to a UV lamp after that. Worked decently.

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.
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Old 02-16-2011   #13
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too funny.

I know a faster way to cure the Radiation Damage. My Boss told me to just shine a LASER down the glass, that would cure it. That was several years ago. Not many people have UV LASERS though. I took his word for it, did not try it.
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Old 02-16-2011   #14
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Quote:
Originally Posted by Brian Sweeney View Post
Not many people have UV LASERS though.
And even less people will have a soft UV LASER. The common excimer LASERS probably will not do, given that they have a hard spectrum and high power UV-C lamps are not effective either.
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Old 02-16-2011   #15
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Quote:
Originally Posted by phil.wright View Post
OK Brian I stand somewhat corrected about it not being a coating, yet the yellowing DOES give unique properties - if you want a lens to perform naturally, why buy an interesting lens like this and then take away the very thing that makes it interesting?

I see this as being no different than sending a vintage lens out for a CLA. Would you buy a vintage lens with haze and fungus and consider cleaning it detrimental to its unique character?
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Old 02-16-2011   #16
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Quote:
Originally Posted by phil.wright View Post
Well, why buy a scratched lens if you don't want a scratched lens (unless you can't afford an unscratched one in which case you are going to have to pay more for it to be repaired blah blah).
Well if there was a way to unscratch lenses that only involved shining UV light down them and that's it, you can bet that I'd buy a lot of scratched lenses.

Yellowing is basically just an easily remedied form of damage. Historically accurate decomposition largely doesn't do anything for me photography-wise. Leather goes bad over time, too, but when buying a folder I still prefer one with a good bellows over one with an authentically decomposed one.
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Last edited by rxmd : 03-06-2011 at 21:52.
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Old 02-16-2011   #17
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Thanks for the post and information, fates. I am going to order one of these and besides I can use the "work Lamp" aspect too. My eyes need all the help they can get!
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Old 02-16-2011   #18
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Quote:
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I thought this was the fastest way: http://web.aanet.com.au/bayling/repair.html
You sure have a strange sense of humor...
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Old 02-16-2011   #19
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The yellow makes it worthless for color pics imparting a yellow brown cast. That is why people want it gone.

Does sunlight permanently fix the yellow or at least for a year?

I once got a yellowed summicron. Was in absolute factory new mint perfect condition otherwise. What a shame as I returned it.
It was to be a lens for my iii f,
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Old 02-16-2011   #20
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Does sunlight permanently fix the yellow or at least for a year?
As the radioactive decay does not stop, the lens will over the course of time go yellow again.
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Old 02-16-2011   #21
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Quote:
Originally Posted by sevo View Post
As the radioactive decay does not stop, the lens will over the course of time go yellow again.
It will eventually stop when all the thorium atoms have decayed. You may wait a long time as the time for half to decay is about 14 billion years, then the next quarter is 14 billion years, then the next eighth is another 14 billion years, etc...
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Old 02-16-2011   #22
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Damn there's no IKEA where I live, still very good info.
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Old 02-16-2011   #23
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Damn there's no IKEA where I live, still very good info.
Dear Hans,

There might be, sometime in the next in 14 billion years...

Cheers,

R.
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Old 02-16-2011   #24
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Quote:
Originally Posted by phil.wright View Post
Hi Roger,

Well, why buy a scratched lens if you don't want a scratched lens (unless you can't afford an unscratched one in which case you are going to have to pay more for it to be repaired blah blah).

Besides which, there are many scratched/unscratched lenses but, as I said, these are historical oddities that belong to a time and place.

I must admit that I didn't know the Thorium would re-zap the lenses over time but - why do it if you don't want THAT lens for its individual properties?
Dear Phil,

There are no unyellowed thoriated lenses, unless they've been bleached -- so bleaching one makes it MORE unusual in 2011. Why can't you buy a lens for the individual properties it had when it was new, instead of the individual properties (which many find undesirable) resulting from what amounts to an unforeseen design fault?

Cheers,

R.
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Old 02-16-2011   #25
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Quote:
Originally Posted by sevo View Post
And even less people will have a soft UV LASER. The common excimer LASERS probably will not do, given that they have a hard spectrum and high power UV-C lamps are not effective either.
... been here, done that. Just to cure a slightly hazy Summitar lens that now shows heavy signs of element separation after the UV light destroyed the cement...
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Old 02-16-2011   #26
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Quote:
Originally Posted by Ronald M View Post
The yellow makes it worthless for color pics imparting a yellow brown cast. That is why people want it gone.
I don't completely agree with this. I have a Canon 55mm 1.2 AL that is quite yellowed and I loved it for Kodachrome, especially with red subjects. Of course, now that's gone, so I'll have to try it out on some other stock. I may end up trying to clear it after all.
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Old 02-16-2011   #27
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The Canon 58/1.2 used Thorium Glass. I did not know the 55/1.2 also used it. Most yellowing that people see in older lenses is from the Balsam yellowing.

Yellowing in the thorium lenses is much more extreme, looks like a Y1 filter. It is miserable with color film. Of course with Digital, you can try changing the white balance to Tungsten to fix it.

We had some lamps used for UV cured Epoxy. I'll have to find out what wavelength they are.
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Old 02-16-2011   #28
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Quote:
Originally Posted by Brian Sweeney View Post
The Canon 58/1.2 used Thorium Glass. I did not know the 55/1.2 also used it. Most yellowing that people see in older lenses is from the Balsam yellowing.
Yep, it does. 7.5 μSV/h, whatever the hell that means.
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Old 02-16-2011   #29
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Another thing about the yellowed lenses.

I've had a couple Takumar 50/1.4's and comparing a clear lens to
a yellowed one, the clear one was a full stop faster. At 1.4, given the same dim indoor lighting conditions my DSLR wanted to shoot at 1/30 with the clear lens and 1/15 with the yellowed one.
In other words, the yellowing reduces the amount of light reaching the film by a stop or possibly even more depending on how bad the yellowing has become.

So, by all means you'll be doing yourselves a favor clearing those great old lenses.
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Old 02-16-2011   #30
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Quote:
Originally Posted by Brian Sweeney View Post
The Canon 58/1.2 used Thorium Glass. I did not know the 55/1.2 also used it. Most yellowing that people see in older lenses is from the Balsam yellowing.

Yellowing in the thorium lenses is much more extreme, looks like a Y1 filter. It is miserable with color film. Of course with Digital, you can try changing the white balance to Tungsten to fix it.

We had some lamps used for UV cured Epoxy. I'll have to find out what wavelength they are.
Or indeed downright brownish, if you leave it long enough. I assume you have a pre-1950 Aero Ektar swilling around somewhere?

(Preferably not under the bed. Conversation between a friend and a third party: Third party, "How radioactive are they?" Friend, "Not very, but you wouldn't want to store them under the bed." Friend, reporting story to me: "He went a bit pale. He'd been storing five under his bed.")

Cheers,

R.
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Old 02-16-2011   #31
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Quote:
Originally Posted by Brian Sweeney View Post
The Rigid Summicron does not use Thorium. The early Collapsible Summicrons, serial number under "About" 1050000 use it, and i have three of them.

The yellowing in a Rigid Summicron is from the Canadian Balsam turning yellow with time. I have never tried bleaching it out, please report the results with it.
I have a made in Germany Wetzlar with a 24331XX serial. It's yellowing was very much like the Thorium (I've read Lieca denied using thorium, but then later admitted that they did) yellowing... actually, let's call it "monkey sh*t browning & dark clouding" so people don't confuse this process with removing desirable properties. A yellow or center filter is vastly superior to the decayed glass. Like others have said the discoloration will return. Might take a decade+ tho...

It cleaned up faster than a Takumar, but it is also 1/3 the surface area. 2 days of exposure and it is crystal clear again, there's no discoloration at all. I've only seen horrible results of Balsam sliding out, and this really looks... well looked like Thorium yellowing. Now I'm wishing I had documented the process this time.

Quote:
Originally Posted by pobe View Post
I thought this was the fastest way: http://web.aanet.com.au/bayling/repair.html
Dear god, somebody please contact this bloke and tell him to revamp his website to not encourage people to:
  1. destroy the best still photo lenses that behave like cine taking lenses ever made. They have such great long barrel throws and are super smooth. As good as Zeiss Cine mechanisms.
  2. NEVER do this and poison themselves.
What a tool.
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Old 02-16-2011   #32
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A Summicron with a serial number that late is well past the use of Thorium Glass. I have taken apart 8 or so of this series Summicron.

However: it is possible that the lens has radiation damage, depends what it was used for in the past. I've locked cameras into a vacuum chamber with radioactive elements before.
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Old 02-16-2011   #33
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Not to divert the OP's original intent, but for my MC Rokkor 28mm f2.5 SI lens with a yellow/brown internal element, I found that simply screwing on an 82A filter seems to restore good color performance... and it's really fast, goes on in less than 15 seconds...
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Old 02-16-2011   #34
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What kind of bulb is in the IKEA lamp?
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Old 02-16-2011   #35
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It looks very much like a Seoul P4 LED.
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Old 02-16-2011   #36
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It looks very much like a Seoul P4 LED.
Thanks.....
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Old 02-16-2011   #37
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The bulb is pretty much encased in the lamp, and I can't see a quick way to pull it out and read any markings.

Quote:
Originally Posted by Brian Sweeney View Post
A Summicron with a serial number that late is well past the use of Thorium Glass. I have taken apart 8 or so of this series Summicron.

However: it is possible that the lens has radiation damage, depends what it was used for in the past. I've locked cameras into a vacuum chamber with radioactive elements before.
Yeah, I was surprised to see a rigid 1970 lens that appeared to have Thorium "Monkey Sh*t Browning", but I figured I was new to Leica glass ownership... and what I don't know can fill an 80 gallon drum. I'll post back in another ten years and let everyone know how the discoloration is proceeding.

I was so apt to clear it up, I didn't think too much of it's possible odd nature, and in retrospect should have documented the process.


Quote:
Originally Posted by JFH View Post
Not to divert the OP's original intent, but for my MC Rokkor 28mm f2.5 SI lens with a yellow/brown internal element, I found that simply screwing on an 82A filter seems to restore good color performance... and it's really fast, goes on in less than 15 seconds...
Sure, if you like loosing light, can't stand to put the camera down for 6-12 hours (or attach another lens in the interim), or part with the 5.99 USD for a lamp...

Wow, I thought most shooters liked their glass clear, non-tinted, and as fast as it was designed to be?
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Old 02-22-2011   #38
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Originally Posted by hans voralberg
Damn there's no IKEA where I live, still very good info.

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Dear Hans,

There might be, sometime in the next in 14 billion years...
Cheers,
R.

Roger,
I just wanted to say this was one of the funniest posts ever... at least to me. Really cracked me up!
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yes, this is correct
Old 02-23-2011   #39
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yes, this is correct

This was my reason for deciding against an old Pen 38/40/42 lens as they will give a brown cast to the images unless cleaned of the light.

I have a low power UV laser, but it's not powerful enough to clean a lens, but is useful for being able to tell if a vintage lens is blocking UV light or not.


Quote:
Originally Posted by Ronald M View Post
The yellow makes it worthless for color pics imparting a yellow brown cast. That is why people want it gone.

Does sunlight permanently fix the yellow or at least for a year?

I once got a yellowed summicron. Was in absolute factory new mint perfect condition otherwise. What a shame as I returned it.
It was to be a lens for my iii f,
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Old 03-03-2011   #40
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Hello,

I bought this very lamp yesterday and have let my Takumar 50 1.4 bask in its light for over 20 hours.
I really should have taken accurate pictures of the lens before the process, because I'm not sure that it was actually bleached when I look at it now.

Just in case, would a serial number of 1725xxx still fit with the period when they used thorium?
Or is shining LED light in it useless?

Thanks.
(And I just noticed my Pen F 40mm is a little bit yellow too. Did every lens in this serie use thorium?)
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