Lanthanum & rare earth

Discussion in '35mm Cameras and Accessories' started by Dave Wooten, Apr 24, 2005.

  1. Dave Wooten

    Dave Wooten Subscriber

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    Has anyone done a comparison of russian Industar lenses---Industar 61 and Industar 61 L/D.....Does the L/D infact contain rare earth and the radio active element Lanthanum, and if so does this improve contrast etc....

    The L/D lenses I believe were issued with the Fed 4 and Fed 5 series, and are also leica screw mount etc.

    Maybe some one has an example of each?

    Thanks
    Dave in Vegas
     
  2. Ole

    Ole Moderator Staff Member Moderator

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    A quick note about Lanthanum: It isn't radioactive!

    But lenses with Lanthanum glass usually are, because trace amounts of Thorium are next to impossible to separate from the Lanthanum. And Thorium is radioactive.

    Lanthanum belongs to a group of elements called "rare earth elements" for historic rason only. They are not particularly rare, nor particularly earthy, but the name seems to have stuck. Most of them are named for Ytterby, a village just outside Stockholm, Sweden (Ytterbium, Yttrium, Terbium, Erbium, Holmium, as well as Scandium)!
     
  3. Dave Wooten

    Dave Wooten Subscriber

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    Thanks Ole!

    You are always such a treasure of information.....is there any truth to the possibility that a lense containing lanthanum is any more desireable than one without? Are they more contrasty as claimed?
     
  4. jimgalli

    jimgalli Subscriber

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    Lots of romance and urban myth. Else why would a 210 Lanthar be 2 1/2 times as much as it's sibling Heliar. I think it would be easy to prove any slight gains in contrast are long since eclipsed by modern coatings.
     
  5. Ole

    Ole Moderator Staff Member Moderator

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    Both yes and no. They are not noticably contrastier, and certainly not compared to modern multicoated lenses. However the Lanthanum glass made some corrections far easier, so that the first APO Lanthanum lenses had far better colour correction than anything made before. So the focus is in a way more precise...

    I do know that I have a 150/4.5 APO-Lanthar with a deep scratch on the rear element that is still my best 4x5" lens. I won't claim it's sharper, contrastier, or in any measyrable way "better" than other lenses, yet I find the pictures shot with it more pleasing. I have compared it to several other lenses, and there really is something special about it!
     
  6. jimgalli

    jimgalli Subscriber

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    Hmmm. Sounds like my Heliar. Oops, we hijacked Dave's thread.
     
  7. Dave Wooten

    Dave Wooten Subscriber

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    that's fine I'll just hang around and maby learn something
     
  8. eumenius

    eumenius Member

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    Hi Dave,

    both lenses are equally good, as well as its sibling Industar-61 L/Z MC (M42 multicoated version). They definitely are from the very best lenses ever made by USSR - a highly-improved Tessars with close focusing abilities. From my own experience with these I can say that the lanthanum version yields a better color saturation and contrast, also it's claimed to have a better overall resolution. I-61 makes also a good enlarger lens, and gives no flare in all lighting conditions due to its design (built-in hood and small frontal element). I can recommend the lanthanum MC edition - it's improved, really. But a plain I-61 is a great performer, too.

    Cheers,
    Zhenya

     
  9. Dave Wooten

    Dave Wooten Subscriber

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    Thanks all very informative....I have acquired a Fed 5 B with the lens in discussion....I will put a roll through it.

    Dave in Vegas
     
  10. rjr

    rjr Member

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    Dave,

    this is exactly the approach I usually recommend: get a decent lens with some ugly and large rear cap in shape of a FED5. 8)

    BTW, the L/Z version is still in production (http://www.lzos.ru/en/ind_61_l3.htm), the L/D should be available in it´s last version with NOS FEDs.

    Zhenya, LZOS lists the J9 as "not available" - did they pull it from production? :-(
     
  11. MattCarey

    MattCarey Member

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    Rare earths are generally found as oxides. As I have heard, "Rare" refers to the fact that it is very hard to separate the metal from the oxygen.

    Rare earths are very heavy atoms. Silicon and oxygen (the main components in glass) are rather light. I suspect that the rare earths increase the refractive index of the glass because of this. I should probably google this before saying something stupid...

    Matt
     
  12. eumenius

    eumenius Member

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    Hi Roman,
    glad to see you here again! :smile: On your place I shouldn't believe what LZOS site says - that's exactly the place where the right hand doesn't know what the left one does :smile: J9 should be still in production, though they made maybe a million of them already? Anyway, I don't think that they brew glass for their photo lenses now. Maybe in case of J9 and, say, J61 they just assemble whatever they have inherited from USSR past...

    PS. One of my friends who worked at LZOS someday told me that most of the color filters made under the brand of LZOS were in fact made by Pentax - optical glass factory in Izum was unable to output consistent quality, so the glass was imported :smile: The only local filters, he say, were the yellow ones, and not always!
     
  13. Kiron Kid

    Kiron Kid Member

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    Quite a few of the older Canon rangefinder's use this glass too. No wonder, I've never had children....

    Kiron Kid
     
  14. MichaelBriggs

    MichaelBriggs Member

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    Many so-called Lanthanum glasses are actually Lanthanum/Thorium glasses. Many of the manufacturers preferred to emphasize the Lanthanum content and downplay the Thorium content. Period literature makes it clear that Thorium was intentionally included for the desirable optical properties of this glass: a high index of refraction with a low dispersion. This helps reduce chromatic and spherical abberations.

    The radioactive lenses that I have measured are much to radioactive to be explained by the extremely slight radioactivity of Lanthanum, or by contamination with Thorium. The amount of Thorium is too large to be contamination.

    Most major lens manufacturers used Thorium glass: Kodak, Voightlander, Schneider, Pentax, Nikon, etc. The Apo-Lanthars definitely contain Thorium. I don't know whether Russian lens manufacturers used thorium glass. One possible sign is that the glass ages to a tea color. This can be cleared via exposure to UV light.

    Thorium glass is no longer used -- optically similar glasses without thorium are available.

    For more on thorium glass, see my Aero-Ektar webpage: http://home.earthlink.net/~michaelbriggs/aeroektar/aeroektar.html
     
  15. Donald Qualls

    Donald Qualls Member

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    I have one of the radioactive thorium-glass Super Takumar lenses. Aside from yellowing (cause by decay products of the thorium, and I'm told that a few weeks under UV light will correct it -- trying to find an economical way to set that up without exposing the lens to the heat of direct sun), it's an excellent lens indeed - but based on my experience in the last few months, not enough better than my Tessars and Skopars to be worth the risks of grinding the thorium glass or the expense of properly disposing of the radioative and toxic residue.

    As noted above, there are now glasses that effectively duplicate the optical properties of these radioactive glasses without the potential health issues. However, I'm not getting rid of my Super Takumar -- I don't store it in the headboard of my bed, or use it as a loupe, and I don't consider it any more hazardous, when stored with my camera gear and used on the camera as a lens is intended to be used, than ordinary photo chemicals used in their common applications.

    Would I buy another one if it were crystal clear, clean aperture, and otherwise good condition? In a heartbeat, if I could afford one (and I might, before too much longer).
     
  16. Jim Chinn

    Jim Chinn Member

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    I remeber an article in the old Camera and Darkroom that discussed using a spcecial light to remove "impacted photons" from older lenses. I don't remember if it was specifically discussing lenses containing trace amounts of radioactive elements. I do believe that it was a UV light source. When I get time I will rumage through my stacks and find it.
     
  17. Dan Fromm

    Dan Fromm Member

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    Um, Jim, I have a small pile of lenses with elements containing Thorium. All had glass yellowed by radiation damage when I got them. The worst of the lot shot distinctly yellow EPP transparencies. Not good. A month or so of basking under a 20w fluorescent BLB tube cleared all of them, including the worst.
     
  18. Ole

    Ole Moderator Staff Member Moderator

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    I rather like the "warm-tone" effect of my APO-Lanthar :smile:

    It's weak, and only ovious when compared to the same scene shot with a "normal" lens. Combined with the smooth rendition the lens is (justifiably) famous for, it's a wonderful effect. I only wish I could afford some more of them - say a 210 and a 300mm...
     
  19. Donald Qualls

    Donald Qualls Member

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    Unfortunately, my Super Takumar 1.4/50 is yellow enough to give about 1/2 stop filter factor, accentuate clouds, and make color prints look muddy -- I've had to stop using it for color. Gotta get a UV light set up and see if I can clear it...
     
  20. titrisol

    titrisol Member

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    Donald, since you are in NC now, sunlight is strong enough this time of the year to leave it near a window and celar it in a couple of days.
    Wrap it in aluminum foil to prevent overheating and use the most of UV
     
  21. Donald Qualls

    Donald Qualls Member

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    Well, today, the sunlight is pretty weak (it was raining vigorously this morning when I took my wife to work), but I get your drift; I might have to put it on a windowsill with some foil on it and see what I get. :smile:
     
  22. titrisol

    titrisol Member

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    Yup, lots of rain this AM, and thunderstorms later in the evening....
    but it was pretty ytdy and wit'll be prety over the weekend :wink: