Super Multi-Coated Takumar 50/1.4 Yellowing
-
A
- Thread starter RLangham
- Start date
Recent Classifieds
-
For Sale Huge filter collection for sale!
- Started by Early Riser
-
For Sale FS: Yamasaki Tele-Congo 240mm f/6.3 Lens
- Started by B.S.Kumar
-
For Sale E6 and Color Chemicals, Stainless Steel Tanks Reels and film storage sleeves.
- Started by orbitaldebris
-
For Sale SILVESTRI RING N 1
- Started by Philippe-Georges
-
For Sale LINHOF AERO TECHNIKA 45 LENS COVER
- Started by Philippe-Georges
Forum statistics
More likely people who know Kiev is close to Chernobyl, but don't understand prevailing winds, or that Industar isn't made anywhere near Kiev (Jupiter, yes, but not Industar).
Lanthanum is a rare earth element and as far as I can tell, glasses with lanthanum oxide replaced glasses with thorium oxide to decrease radioactivity. I would need to know the names of the glasses to look up their optical properties.
The dominant isotope of lanthanum is completely non-radioactive - naturally occurring lanthanum has a tiny fraction of a radioactive isotope, but this is insignificant; so do many other common elements, even carbon (C-14). Lanthanum is element 57 and thorium is element 90 - generally, it's the elements with high atomic numbers that have significant naturally occurring radiation.
There is a lot of myth and lore about photography, lenses, etc on the internet. My best guess is that someone combined "rare earth element" and vague "Soviets are dodgy and different from you and me" feelings to get that lanthanum glasses are radioactive, and then it was repeated until it became legend. They're not.
Here's a report from someone who actually measured the radiation from a thoriated Leica lens (I assume you've all seen this as it's easy to google). The amount of radiation is much higher than you would get from small amounts of industrial contamination in some other glass. https://petapixel.com/2018/06/07/a-radioactive-lens/
The dominant isotope of lanthanum is completely non-radioactive - naturally occurring lanthanum has a tiny fraction of a radioactive isotope, but this is insignificant; so do many other common elements, even carbon (C-14). Lanthanum is element 57 and thorium is element 90 - generally, it's the elements with high atomic numbers that have significant naturally occurring radiation.
There is a lot of myth and lore about photography, lenses, etc on the internet. My best guess is that someone combined "rare earth element" and vague "Soviets are dodgy and different from you and me" feelings to get that lanthanum glasses are radioactive, and then it was repeated until it became legend. They're not.
Here's a report from someone who actually measured the radiation from a thoriated Leica lens (I assume you've all seen this as it's easy to google). The amount of radiation is much higher than you would get from small amounts of industrial contamination in some other glass. https://petapixel.com/2018/06/07/a-radioactive-lens/
I would believe that if people online weren't usually very specific that the lanthanum is what supposedly makes them radioactive. I think in a way Chernobyl is almost more of a cultural icon in the West, in some senses... but in this case I don't think that's the main thing that's involved.
Most of these Kiev and Jupiter lenses under discussion were made long before the Chernobyl accident / disaster in 1986, anyway.
As Donald alludes, the prevailing winds blew west; if partial logic was being applied, people would be applying this scare-tactic to lenses made in 1986-1987 in West Germany. But the reality is that it wouldn't have contaminated glass manufacture in a measurable way. Agricultural products that one would eat were more of a problem.
"Industar" is a label that means a Tessar-type design, not a mark of a particular camera maker. Lenses named Industar (or eg I-61 L/D, which is a common lanthanum-oxide lens to find on a FED) were made by FED in Ukraine, KMZ in Kransogorsk near Moscow, and other places.
As Donald alludes, the prevailing winds blew west; if partial logic was being applied, people would be applying this scare-tactic to lenses made in 1986-1987 in West Germany. But the reality is that it wouldn't have contaminated glass manufacture in a measurable way. Agricultural products that one would eat were more of a problem.
"Industar" is a label that means a Tessar-type design, not a mark of a particular camera maker. Lenses named Industar (or eg I-61 L/D, which is a common lanthanum-oxide lens to find on a FED) were made by FED in Ukraine, KMZ in Kransogorsk near Moscow, and other places.
This is what happened to Bruce Banner, he was so happy with his new Spotmatic he turned into the incredible Hulk.
I always thought Bruce Banner had a lens with yellowing balsam, so the Hulk made no sense to me. I feel like an idiot now. The Takumars probably don't even have balsam, but a modern UV-cured cement.
My Super Takumar was surely made in before 1980 (I bought the camera, used, at a pawn shop in 1981). Were they using UV cured lens cements that early? I know I could buy balsam (sold for mounting microscope slides, but still used by amateur opticians for assembling telescope and eyepiece achromats) as late as the 1990s.
I am pretty sure that UV cured cement has been around much longer than that. Like many advances such as AR coating, some advanced glass types, computing, and flash sync, optical cement was spurred on by R&D advances during WW II. See for example https://www.optical-cement.com/cements/manual/manual.html I don't have any immediate knowledge of what's in a Super-Takumar, balsam may have been used in some industrial applications for I don't know how long, but by the 70s UV cement would have been widely available.
My point was that a balsam failure wouldn't turn anyone into a Hulk, but I also suspect that the Hulk series of films and comics aren't entirely realistic.
According to Andrew Clements' paper "Selection of Optical Adhesives" from 2006, different heat cured optical adhesives that would withstand heat and cold better than Canada Balsam were developed after WWII, and the first fast UV cured lens adhesive was introduced by Summers Laboratories in 1966.
Canada Balsam is still around. I recently saw a ca 100 year old camera with a Rietzschel Linear lens with severe separation. It's an eight element - two groups lens, quite unusual. My immediate thought was that recementing the elements with Canada Balsam could be a fun project, but then I thought that centering the four elements in each group would be too difficult without an optical instrument to help.
- Joined
- Jul 31, 2012
- Messages
- 3,354
- Format
- 35mm RF
So just for everyone's information, I put a few uv led lights over the lens on Wednesday. It is now Saturday and the lens is nearly free of any discoloration. Even after one day there was quite a difference. I'll leave it for a few more days for the heck of it.
Well, I have pointed my camera with the lens at the fluorescent UV tube for circa 36 hours so far, and no observable change seems to have occurred yet, so I must have a much lower intensity light. I'm gonna try an exposure of about a week or so next. Tell me, there's no risk from too long an exposure to UV as long as there's no heat, right?
On an SLR, it shouldn't be an issue as long as the mirror isn't locked up. I'd avoid prolonged high intensity UV exposure on a cloth curtain. You could also see some fading of the leatherette body covering due to UV exposure, but likely not in a matter of a few days or even a few weeks under a UV fluorescent. Direct sun typically takes years to be noticeable there.
It's on a Praktica Super TL3 with a synthetic leatherette, but I have no idea if that's better or worse as far as breaking down under UV goes. Then again it was 15 dollars and I only bought it because it had a Helios 44 on it, so I guess I'll try it and see.
Anyways, it seems to be a relatively dim UV source too. I think it'll be fine.
Use it for just B&W film. No yellow filter needed.
It's not *that* much of a yellow tint
Yep that's true. Maybe the OP can test that. My yellowed 55 Tak sure makes some nice pictures. Love to see a clean one to compare to.
Know where you could find one that was stuffed in a time machine forty years ago and just now popped out, with zero time passage for the lens? That's the only way you'll find one that has never yellowed. Apparently a fully cleared thorium glass element isn't all that difficult to restore, but there's no simple way to be sure the glass still meets the original spec after forty to fifty years of radiation damage has altered the structure of the glass. If the theory about electron displacement is correct, it should be "like new" once the yellow is fully cleared -- but if the yellowing is actually something else, the properties of the glass may change in ways that aren't undone by clearing the color.
FWIW, after I cleared my Super Takumar 50/1.4 (not even 100% cleared), it's still an awesome lens. One of these and a roll of CMS 20 or Copex Rapid can produce images that just about pass for medium format.
From what I have seen, the newest 55mm ƒ/1.8 SMC Takumars, the ones with a rubber focus ring, have not yellowed. They may have different glass. My wife's 1971-vintage 55 1.8 did yellow, but I cleared some of it with an inexpensive LED lamp from Ikea. I did not want to put it on a windowsill because of the heat. That 1971 lens has amazing resolution. I do not want to use the term "kit lens" because I associate that with the cheesy plastic-fantastic zoom lenses sold with low-end D cameras at big box stores.
Last edited:
At least some of those were the same optical formula, but with different glass... either less or no thorium, I have heard. I could be wrong.
This is the route I took with a 55/1.8 and two 50/1.4 Takumars. The Ikea lamp cost around $15 and I placed it just about 1/4” above the lens with foil on the opposite side. The first 50/1.4 was really yellowed and took about two weeks to clear. The other two took about a week each.
For E6 the lenses were improved dramatically and, in the case of the really bad one, I gained almost half a stop. All three lenses are great performers.
I have a question about the Pentax Super Multi Coated Takumar 55mm f/1.8. I think this one is radioactive. One day I used the lens to view some negatives up close, like as a magnifying loupe, for a few seconds, until I realized it's radioactive. Can it cause damage to the eyes for a short exposure like this ? I was very close to it, but for a brief amount of time.
| Photrio.com contains affiliate links to products. We may receive a commission for purchases made through these links. To read our full affiliate disclosure statement please click Here. |
PHOTRIO PARTNERS EQUALLY FUNDING OUR COMMUNITY:  |