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  1. #11
    df cardwell's Avatar
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    (were) the cells in the triple convertible Symmars were reworked to provide better focal lengths

    Are you asking whether the plasmat Symmar cells better than dagor Symmar cells ?

    Sure. Rudolph's Plasmat arrived about 30 years after the Dagor, and he was able to improve the performance by using an airspace.

    The drawbacks of that airspace were flare and ghosting in some situations. Post war coating fixed that. There was another virtue of the Plasmat design, that they were easier to manufacture.

    Here is a listing of the Symmar range c. 1962 (from cameraeccentric.com)
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  2. #12

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    No, what I meant was that I don't know whether the triple convertible Symmars were just the old Doppel Anastigmat Symmars with two extra aperture scales engraved on the shutter plate or whether the focal lengths of the individual cells had been changed to provide more useful focal lengths. The only information I have prior to the introduction of the Plasmat Symmars is the 1934 & 1939 catalogs on Seth's site and neither of them gives any clue as to the focal lengths of the individual cells. Likewise the cells themselves on the DA Symmars I own are not marked with the individual focal lengths, while the cells on the triple convertible Symmars are marked with the focal length. None of the (combined) lenses are the same focal length so I can't compare one against the other.

  3. #13
    df cardwell's Avatar
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    In no particular order, Paul, here is some data.

    First, the link to Schneider serial numbers------ http://www.schneideroptics.com/info/age_of_lenses/

    I have a 1952 f/6.8 Symmar. If it is an f/6.8, it is a Dagor type. It is in a Synchro Compur P shutter, and has a triple aperture scale. It is coated. It is an F:135 / F:260 / F:210. Each cell is inscriber with its F and f.

    The pre-war 6.8s seem to be symmetrical Dagors. A single cell from a Dagor is 1.75x the F of the complete lens, with an aperture of f/13. That should make it easy to compare.

    Remember the Dagors and Protars used symmetry to fully correct the lens, and the usefulness as a single cell was a bonus, each cell being (effectively) a Rapid Rectilinear.







    If it is an f/5.6, it is a Plasmat type.
    "One of the painful things about our time is that those who feel certainty are stupid,
    and those with any imagination and understanding are filled with doubt and indecision"

    -Bertrand Russell

  4. #14
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    Merry Christmas folks! Well, I am inspired and have the day off. I am going to take the front element off my Symmar-S and give it a try to see what I get.

  5. #15
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    Results: Using FP-4 film I removed the front element and focused on a mesh fence about 15 feet in front of the camera. The exposure called for f22 with the full lens, so I doubled the exposure time and kept it at f22. The results were not bad, but were not as crisp and contrasty as the full lens. The rear element on the 180mm lens focused well at about 11", and I didn't really care for the focal length with my 5x7 camera, so I am not sure I will be using this combo. The resulting exposure looked good so it appears to need 2X the exposure.

  6. #16
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    Quote Originally Posted by Ironage View Post
    Results: ...The results were not bad, but were not as crisp and contrasty as the full lens. The rear element on the 180mm lens focused well at about 11", and ... The resulting exposure looked good so it appears to need 2X the exposure.
    So, can we say then, that your experience is, "It will do in a pinch, but don't expect miracles."

    I found this because I've got a 150 Symmar-S and just picked up an old homebrew 8x10 that I'd like to have a bit longer lens for, but don't want to drop an arm and a leg into this until I decide I like it. Frankly I'm not even sure it will cover 8x10 yet, since I haven't had much time to play with it.



    MB
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  7. #17
    Ironage's Avatar
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    Quote Originally Posted by michaelbsc View Post
    So, can we say then, that your experience is, "It will do in a pinch, but don't expect miracles."


    MB
    Yup, that about sums it up. But I only made one text exposure, and I think I would try another before passing judgement. I guess that the 11 inch focal length didn't thrill me either. I was hoping for something a bit longer. The old Symmars are longer focal length when used as a convertible.

  8. #18

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    by any chance did you use an 11 filter? My experience is that the yellow filter removes a lot of the softness when converted.

  9. #19
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    Sure, it will work on a symmetrical lens. Test to see what it does to the pix and if this is something you can use to good effect. Personally, I think the look of half a symmetrical lens is quite beautiful (though definitely not of a technically high quality).
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

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