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  1. #11
    David H. Bebbington's Avatar
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    Quote Originally Posted by Stevopedia View Post
    ...
    Please forgive the ignorance of my question, but what does the number of elements in a lens do for the quality of the photograph? The only affect I can think of a larger number of elements having is an increase in lens flare...

    ...
    A larger number of elements in a lens FUNDAMENTALLY gives a lens designer more possibilities of correcting lens aberrations (which degrade image quality). However, since flare is a measure of how much light gets scattered as it passes through a piece of glass, instead of staying focused as you want it to, more elements also FUNDAMENTALLY mean more flare. Before lens coating came in in the 1940s, this meant that a 4-element Tessar-type lens would always have more contrast than a 6-element Gauss-type (AKA plasmat) lens. Press photographers using Leica, for example, would have both a 4-element Elmar and a 7-element Xenon and use the Xenon only when they needed the extra speed, since the flare was otherwise excessive. The same principle applies to the single-coated lenses of the 40s and 50s - a Schneider Xenar has more contrast than a Xenon (but not as flat a field).

    With super-multi-coating, which came in in the 60s, this difference is much less pronounced, and in fact the difference in contrast between 4- and 6-element prime lenses and even zoom lenses is far smaller, for practical purposes negligible, except that prime lenses almost always have better flatness and zooms, particularly older ones, may have a spot in the zoom range where flare suddenly explodes.

  2. #12
    phenix's Avatar
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    Quote Originally Posted by srs5694 View Post
    I've also got a Vega 11U enlarger lens. I know of one other FSU/Russian lens that's said to have some lanthanum (the Industar 61L/D, which shipped with later FEDs), but I wasn't aware the Vega 11U (if that's the model you mean) also used lanthanum. I'm curious: Why do you like that lens for portraits?
    Yes, it is the Vega 11U. The mount is orfull, but the optics are beauteful. Why for portraits? Because it seams a bit soft at the edges, while crisp but also "gentle" in the middle. I use it in f/5.6, but maybe I should try it in f/8 too...

    Industars also have a lanthanium element. I don't know that of Feds, but the M42 for Zenits is a Tessar type with the back concave element with lantanium. What does this radioactive element do? It makes a 4el lens perform like a 6el one.

    But the radioactivity is very low, dangerous maybe if you sleep with the lens on your chest more than 50 years. BTW, Leica also made some radioactive lenses earlier, but they used radium in their glass. US aerial lenses also have radium in their huge back element (being huge maybe is it more dangerous? - I don't know). The radioactive substance plaied the same role today's low distorsion materials do, but somehow (if not much) better.

    That's why I love "hot" lenses!
    Last edited by phenix; 05-07-2008 at 04:30 PM. Click to view previous post history.
    B&W is silver.

  3. #13

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    Quote Originally Posted by B. Baer View Post
    A larger number of elements in a lens FUNDAMENTALLY gives a lens designer more possibilities of correcting lens aberrations (which degrade image quality). However, since flare is a measure of how much light gets scattered as it passes through a piece of glass, instead of staying focused as you want it to, more elements also FUNDAMENTALLY mean more flare. Before lens coating came in in the 1940s, this meant that a 4-element Tessar-type lens would always have more contrast than a 6-element Gauss-type (AKA plasmat) lens. Press photographers using Leica, for example, would have both a 4-element Elmar and a 7-element Xenon and use the Xenon only when they needed the extra speed, since the flare was otherwise excessive. The same principle applies to the single-coated lenses of the 40s and 50s - a Schneider Xenar has more contrast than a Xenon (but not as flat a field).

    With super-multi-coating, which came in in the 60s, this difference is much less pronounced, and in fact the difference in contrast between 4- and 6-element prime lenses and even zoom lenses is far smaller, for practical purposes negligible, except that prime lenses almost always have better flatness and zooms, particularly older ones, may have a spot in the zoom range where flare suddenly explodes.
    Thank you very much for that explanation, B. Baer, I found that to be very informative.

    Also, phenix, FWIW, there was at lease one Takumar that had a radioactive element--the 50/1.4 Super Takumar. Some examples of that lens have thorium glass. There could be other radioactive Takumars, though.
    Last edited by Stevopedia; 05-07-2008 at 07:47 PM. Click to view previous post history.

  4. #14
    phenix's Avatar
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    I remember Stevopedia, you are right about the Takumar 50/1.4! This was the lens Asahi anounced to have equaled the resolution of a Leica 50/1.4, and tests did prove it (Asahi in f/8, and Leica in f/4 or 5.6). It was an M42 mount, as Pentax didn't introduce the K-mount yet. I think that the later K-mount Takumar, and the next generation of SMC-M 50/1.4 were still the same "hot" lens, plus the super multi-coating, but I'm not at 100% sure. Meanwhile, the SMC-A 50/1.4 was, for sure, not a "hot" lens anymore.
    Last edited by phenix; 05-07-2008 at 10:30 PM. Click to view previous post history.
    B&W is silver.

  5. #15

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    I have shot Pentax all my life. The 50/2 is an excellent lens, far underpriced for its capabilities. At f8 there is no difference from the 50/1.4. I have three 50/2, and all compare favourably to the 50/1.4. If I need to shoot at f4 or larger, I use the 50/1.4. The 1.4 is better at the wide aperatures.

    As for the number of elements, I have a Schneider Kruesnach Radionar (three element) 80/2.9 on a folder that is absolutely stunning when used in its oprimal f-stop range of f8-f16. I also have a 105/3.5 Rodenstock Trinar on a folder that is not sharp in the corners (6X9) except at f22. Ya just have to try 'em...
    Rick Jason.
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  6. #16
    phenix's Avatar
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    Quote Originally Posted by ricksplace View Post
    As for the number of elements, I have a Schneider Kruesnach Radionar (three element) 80/2.9 on a folder that is absolutely stunning when used in its oprimal f-stop range of f8-f16. I also have a 105/3.5 Rodenstock Trinar on a folder that is not sharp in the corners (6X9) except at f22. Ya just have to try 'em...
    The biger the film format you shoot, the lower are the requirements a lens has to meet.
    B&W is silver.

  7. #17

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    Quote Originally Posted by ricksplace View Post
    I have shot Pentax all my life. The 50/2 is an excellent lens, far underpriced for its capabilities. At f8 there is no difference from the 50/1.4. I have three 50/2, and all compare favourably to the 50/1.4. If I need to shoot at f4 or larger, I use the 50/1.4. The 1.4 is better at the wide aperatures.

    As for the number of elements, I have a Schneider Kruesnach Radionar (three element) 80/2.9 on a folder that is absolutely stunning when used in its oprimal f-stop range of f8-f16. I also have a 105/3.5 Rodenstock Trinar on a folder that is not sharp in the corners (6X9) except at f22. Ya just have to try 'em...
    All of the Pentax normals are quite good, the 55/1.8's are a classic design. The 50mm f1.7 is ridiculously sharp (the sharpest of the non-macro 50's), while the 1.4 and 2.0 do better with people and the 1.2 is one of the best 70's-era f1.2 normals. Needless to say the 50 macros are excellent and the 40/2.8 is a tiny wee gem.

    The downside to the 50mm f2 is wide-open performance and distortion, but it is very underrated for its performance and a much better lens than many think.

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