FL and coverage for 11x14 Series V Protar?

Discussion in 'Large Format' started by clyde_rogers, Sep 20, 2002.

  1. Hi, all.

    I have a nice, very old brass barrel Bauch and Lomb Zeiss
    Protar, series V, 11x14, that I got for future ULF work. Can
    anyone tell me the focal length and actual coverage of this lens?

    Thanks much!
     
  2. There are many different coverage figures one sees for the Protar V designs - between B&L and Zeiss catalouges, you typically see a full plate size difference. The typical coverage angle quoted is 11 degrees but this is for small stops (i.e., f/45) and at wider stops I think a figure of 95-100 degrees is more realistic.

    As far as I know, the Protar Vs were available in 141mm, 183mm and about 210mm. The 141 is really meant for a 5x7 but will cover 8x10 quite nicely at small stops (i.e., f/45). The 183 is suggested for 8x10 but again is supposed to cover 11x14 at small stops. You need about 450mm minimum to cover an 11x14 frame. The 210mm will manage that very nicely even at wider stops and with a bit of stopping down will even give you reasonably modest movements. The 183mm is going to find it difficult to reach the corners even stoped down and I suspect even if it makes it, the corners will not look particularly good.

    You can find the true focal length by autocollimating but the quickest way to do it might be to focus on a scale or coin till you get a 1:1 magnification on the ground glass i.e., same size image on the ground glass. Measure the bellows extension and divide by 2 and that should give you a pretty close approximation to the tru focal length.

    Cheers, DJ
     
  3. My 1907 B&L catalog states that the focal length for the 11x14 series v protar is 10.5". It states the angle of view is 110 degrees.

    Pete
     
  4. Clyde,

    I've used the 183mm Protar V. The one I had did not cover 11x14, it's image
    circle fell short at small stops. OTOH, Kerik also has the same lens and says
    his covers 7x17 no problem so there must be some variable samples out
    there. If this is the fl you're looking for 'try before you buy' would be good
    advice.

    The 210 Protar V seems to be the magic focal length that does cover 11x14
    (or more) sufficiently. It's also the one you'll least likely see on the used
    market.

    Happy hunting!

    Cheers,
    Roger...
     
  5. I tried the close focus test, and it gives the same 10.5" (267mm)
    the catalog does. I set the lens to f64 (there's no mark for f45) at
    infinity, and although I can't check it accurately on my tiny little
    5x7, it is clear that the image circle easily exceeds 20 inches
    before mechanical vignetting.

    Thanks much for the useful information and advice.
     
  6. I have a 390mm B&L Series V Protar that has a 36 inch + image circle, I showed it to Ron Wisner and I understand that the B&L's cover 90 degrees and the Ziess about 110 degrees. I was also told that the longer focal lengths are hard to find, but you might try as it would make a great ULF lens.
     
  7. As far as I know there are five brands for the Protar V lenses:
    -Carl Zeiss
    -B&L
    -Ross
    -E.Krauss
    -An Italy company (and I forgot the name).

    I have this brands in different focus length. I have tested them and results that E. Krauss has the largest coverage, then Ross..Zeiss and last B&L.
    If you are interest please vist my homepage at:
    http://www.greenviewclub.com/Chat/CameraManual/Protar/Protar.htm

    Edward Chung
     

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