What's wrong with this lens?

Discussion in 'Large Format Cameras and Accessories' started by matt miller, Jul 29, 2005.

  1. matt miller

    matt miller Subscriber

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    I just received, today, a 3x4 speed graphic that I bought on ebay. The lens that came with the camera is a Carl Zeiss Jena Tessar 1:4.5 f=15cm. It resides in a dial set compur. When trying to focus the camera, I couldn't get a focused image to show on the ground glass unless I racked it all the way in; to roughly 1.5 inches from the ground glass. What's going on here? The serial # on the front element is 1194375, the back element says 94375. I assume they're a match, but maybe not. Why won't it focus right? I'm clueless. Maybe I should buy Jim's Xenar?

    Thanks for your help,
    Matt
     
  2. User Removed

    User Removed Guest

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    If it is a wide angle lens, it will be closer to the film plane. Does the lens have decent coverage?
     
  3. matt miller

    matt miller Subscriber

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    It's a 15cm (or 150mm, or 6") lens, so to focus at infinity the lens should be roughly that distance from the ground glass. It won't show a focused image unless it's about 1.5" from the ground glass. I just don't know why.
     
  4. Jorge

    Jorge Inactive

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    Havew you tried it without the back element? You might have a convertible lens....
     
  5. medform-norm

    medform-norm Member

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    Did someone play around with this lens, took it apart and put it back together in the wrong way? Do all the elements look as if they could be reversed? Could you show some pics of the lens itself if you thought that would help?
     
  6. jjstafford

    jjstafford Inactive

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    Can we see a picture of the camera? The images might still be on ebay. Point us to the item #, please.
     
  7. matt miller

    matt miller Subscriber

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    Here's the ebay listing: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7530203368&rd=1&sspagename=STRK:MEWN:IT&rd=1

    I just tried removing the rear element & it didn't change much. I turned the lens around & held it up to the ground glass & that didn't change much either. Could improper spacing cause it to be that far off? I noticed that the rear element is missing 2 numbers compared to the front. Weird.
     
  8. matt miller

    matt miller Subscriber

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    I just wrote the seller & asked him how he knows "the lens is sharp".
     
  9. jimgalli

    jimgalli Subscriber

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    You should buy Jim's Xenar :D

    The front group on that lens can be disassembled for cleaning. All of the elements should face "out". Bowed towards the front of the camera. Maybe someone took it apart for cleaning and reassembled it wrong.
     
  10. jjstafford

    jjstafford Inactive

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    The reflections on the lens don't look right, but it is hard to see well.
     
  11. Dan Fromm

    Dan Fromm Member

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    Matt, the rear cell's s/n often has the leading digits truncated. 1194375 on the front cell, 94375 is OK

    I don't agree with Jim Galli that its possible to assemble the front cell of a tessar incorrectly and not know it real fast. The first element is planoconvex [front (| or a meniscus (( ], the second is biconcave [ front )( ]. Check that. The front cell should bulge out in front, curve in at the rear. This is pretty far-fetched, but are you sure that there are two elements in the front cell?

    Good luck, keep us posted,
     
  12. matt miller

    matt miller Subscriber

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    If the front group comes apart I can not figure it out. How many elements does a tessar have & in what grouping are they? The lens shows four reflections, two large & two small, whatever that means. I really need to learn something about lenses.

    I've attached a photo of the back of the front group. To me, it appears there is only 1 element in the front & one in the back. The back is quite a bit thicker however. The front element bulges toward the front & appears to be flat on it's back side. The rear element bulges toward the rear & is flat on it's back side.

    After looking closer at my camera, it appears that it is set up (infinity stops & RF) for a 5" lens, not the 6" lens that came with it. Figures.
     
  13. jjstafford

    jjstafford Inactive

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    Matt (and others help, please). Would a 135mm lens work on that bed? If it would, hit me with a PM. I'll send you a not-so-hot but working 135mm lens in shutter with retaining ring, gratis. I have a bunch of things to ship tomorrow, so sooner is better.
     
  14. Seele

    Seele Member

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    Matt,

    The Tessar consists of four elements in three groups, two air-spaced at the front and a cemented doublet at the back. The f/4.5 version of that period are usually constructed in the way that the rear doublet was spun into its cell, therefore it is a sealed unit, so no problem with having missing bits there.

    At the front, the two single elements were spun into their own cells, and they screw into each other, then into the front of the shutter; the inner one is a negative while the front a positive.

    Judging from the last attached photo of the close-up of the inside of the front cell, it seems like the inner negative is missing; the inside thread of the cell should be what holds the the negative cell in place. Without the negative, the focal length will become much much shorter (and the correction right out of the window), thus explaining why the image can only focus when the lens is racked that close to the focussing screen.
     
  15. medform-norm

    medform-norm Member

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    We second Seeles feeling that there's an element missing from your lens. Guess it's time for a word with whoever sold you that thing.

    The rangefinder cam should not matter, nor the fact that the camera was intended for a different focal length.

    (And maybe Jim can give a discount on the Xenar to help out a fellow APUG-ger.)
     
  16. Ole

    Ole Moderator Staff Member

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    Also: The rear group of a Tessar has almost zero power, it is mostly for correction. No Tessar is convertible.
     
  17. MikeS

    MikeS Member

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    Yes, a 135mm lens would work fine on that camera! As it's a Speed Graphic, if the focal plane shutter is in good working shape, then having a working shutter on the front isn't as important!

    -Mike
     
  18. matt miller

    matt miller Subscriber

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    jj,

    Thanks for the offer. I'll take you up on it. (see pm) I'd like to use a lens that will match up with the bed scale, infinity stops, & RF. Maybe a 135 is it. If not, I'll be sure you get it back in the same condition. Thanks.

    I've contacted the seller about the lens, but have received no reply yet.

    Thanks for the help everyone.
     
  19. Dan Fromm

    Dan Fromm Member

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    As you've been told already, a tessar consists of two single elements in the front cell (in front of the diaphragm) and a cemented doublet in the rear cell (behind the diaphragm). You should see four strong reflections and no weak ones from the front cell, two strong and one weak from the rear. The weak reflection from the cemented doublet's glass-cement-glass interface can be hard to see.

    It seems that you've been had. Or perhaps the seller has a problem. At the least a price adjustment is in order.

    BTW, why did you get a 3x4 Speed Graphic? And why not a Pacemaker?
     
  20. matt miller

    matt miller Subscriber

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    I don't really know the difference Dan, so I can't say. This is my intro to Graphics. I wanted something quicker than my 8x10, that I can handhold & focus with RF or bed scale. What's the difference between a speed & a pacemaker?
     
  21. Dan Fromm

    Dan Fromm Member

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    Matt, go to www.graflex.org and poke around. Read the FAQs. Work your way through the site map. Also buy a copy of Graphic Graflex Photography, 10th edition or later.

    There were something like four models of Speed Graphic made, in sizes ranging from 2x3 to 5x7. The Pacemaker Speed Graphic (2x3, 3x4, 4x5) is the most recent model. Has a simpler shutter, only six speeds, made of better material that's more reliable than older ones. Also has a variety of upgrades that make it the nicest to use.

    3x4 is an orphan format, with relatively few emulsions available. Unless, that is, you buy larger film and cut it down.

    2x3 is another orphan, 2x3 Graphics are best used with roll holders.

    Good luck, don't forget to look before you leap,