Circular Marks on Print

Discussion in 'Enlarging' started by Peter Williams, Apr 4, 2007.

  1. Peter Williams

    Peter Williams Member

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    I have been back and forth through the forum looking for an answer to this problem and I'm coming up dry. I am getting circular- or semi circular - marks on my prints and I can't figure out why. The attached photo is an example of one, but I have other prints where there is a very visible complete circle burned into the center of the image. What could be causing this? Thanks.

    Peter
     

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  2. MattKing

    MattKing Subscriber

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    Three guesses:

    1) problem with the enlarger light source;

    2) problem with the condensers or mixing box;

    3) reflection off of the rim of the enlarger lens.

    Matt
     
  3. scootermm

    scootermm Subscriber

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    my guess would be the possibility that theres a circle shape on the trays you process the prints in. if you happen to develop the print face down in a tray with a raised circle in the bottom it could cause that perhaps.

    like I said... merely a guess.
     
  4. reellis67

    reellis67 Subscriber

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    Is there a hair on the top (facing the light source) of the enlarger lens? It looks very soft, like something not in the plane of focus.

    - Randy
     
  5. Sparky

    Sparky Member

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    Tell us what enlarger, format, etc... was and maybe we can take some educated guesses..! I'm wondering if you placed some sort of mildly radioactive object on top of the paper box.
     
  6. Vaughn

    Vaughn Subscriber

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    What type of enlarger are you using? (Condenser/diffusion/cold light)

    Since it is a darker circle, it probably is not something in the light path -- that would be lighter than the rest of the image.

    Something that different in tonality should be visible when using the neg carrier without a neg -- put a white piece of paper on the baseboard and see if you can see the circle. If you can, then start changing things (focus, position of condensers, blocking possible sources of reflections, etc).

    Its time to play dectective!

    Vaughn

    PS...nice image...

    PS2...Sparky has a point -- lightly fog a piece of paper w/ room light and process it to see if it is the paper.
     
  7. Peter Williams

    Peter Williams Member

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    Ok - The paper is fine. I am using a Beseler 45MX condenser enlarger, 6x8cm negative, 4x5 glass negative carrier, Ilford MGIV Pearl 8x10 paper, El Nikor 105mm lens. Developed in Nova tank, Dektol, Ilford Rapid Fix. Whatever it is, it's really weird.
     
  8. bdial

    bdial Subscriber

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    How old is the enlarger bulb? I wonder if it has shed some of it's tungston onto the glass unevenly...
     
  9. Ole

    Ole Moderator Staff Member

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    That looks like a "Niebelungen-ring", so named fron Wagner's habit of using his beer stein as a paper weight to keep the finished sheets in place when he was composing. :tongue:

    Any chance of something with a circular bottom having rested on your paper?
     
  10. ChuckP

    ChuckP Subscriber

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    Are you using a mask in your 4x5 carrier to the 6x8 negative size? Not sure how this would cause your problem but it would cut down on strong light that might cause relections.
     
  11. Poco

    Poco Member

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    I had this kind of problem with a chromega E, though it wasn't a circle but 4 dots of added density in the shape of a square that showed up in prints. Turns out there were four bright screwheads within the bellows assembly that were somehow reflecting down through the lens and onto the print -- very strange since they weren't in direct line of sight of the lens, but apparently light bounces around in very strange ways up there.

    If your enlarger uses a lens cone, I'd be suspicious of the point where the vertical sides make the abrupt turn into the mounting ring. That's the kind of edge that can catch the light and form a bright ring that somehow reflects down onto the paper. But basically it's just a matter of taking off the lens (or looking down through the negative stage) and hunting for any source of a bright circle and flocking it.
     
    Last edited by a moderator: Apr 5, 2007
  12. Peter Williams

    Peter Williams Member

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    Thanks for the advice. This lens is mounted in a lens cone. I'll check it out tonight.
     
  13. Sparky

    Sparky Member

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    Drinking beer in the darkroom perhaps?? I wonder if that was Wagner's inspiration for 'der Ring'...!!!

    Anyway listen - try this. So it (the ring) doesn't show up on a contact? And you're sure it's not the paper? Have you duplicated it on several prints - different papers? And it's definitely not on the film? Try to see what happens when you shift the neg in the carrier - does the ring move with it? Also try changing the orientation of the lens, carrier - and light source if possible. Each of these things you should try independently, and see if you can determine a relationship...
     
  14. Monophoto

    Monophoto Member

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    Are there any stray light sources in your darkroom? Light leaks from your enlarger. Reflective surfaces in the vicinity of the enlarger?
     
  15. matti

    matti Member

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    Looks like when I mounted my lensboard wrong, so I get a light leak at the edge of it.
    /matti
     
  16. Roger Hicks

    Roger Hicks Member

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    As we say in English, flock that for a game of soldiers...

    I assume the circle doesn't appear on a lightly fogged piece of paper that was NOT exposed using the enlarger.

    Cheers,

    R.
     
  17. Kapono

    Kapono Member

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    Newton ring? Was it just the one print?
     
  18. Kapono

    Kapono Member

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    Oh...Wagner

    Sorry, I did not quite catch on to Ole's post earlier. Der Ringe des Niebelungen...

    Maybe introducing moist air over the neg will cause just enough expansion on the emulsion side to warp the neg to make a newton ring. Try a non-glass carrier. Really dry air, or nitrogen, is good for dusting off if you use a compressed gas. Blowing by breath to dust off is pretty humid. Any other ideas?
     
  19. Peter Williams

    Peter Williams Member

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    I printed again with a different lens (that being the only variable change) and it came out fine, so the problem is likely either with the lens itself, or the mounting. Thank you all for your input.
     
  20. glbeas

    glbeas Member

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    If it's a problem relating to the focal length of the lens maybe the gap between the neg and the condensor was not set right for that lens. You can get similar effects when you set the gap overly wide as if for a 35mm neg and use a MF neg and lens.
     
  21. Murray@uptowngallery

    Murray@uptowngallery Member

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    Like Gary said...I was starting to wonder if there was some inadvertent focussing of the lamp due to an unfortunate combination of enlarger component positioning.

    I recently started looking for reading material on point source enlarger light sources, and apparently it is common to get 'burn spots' when the lamp isn't where it should be...unfortunately I don't know what the proper combination is that eliminates the phenomenon.

    Now that I think about this a bit more, is it possible the lamp was actually focussed on the negative instead of spread out to cover the neg. properly? This would be another way of saying wrong lamp position relative to the optics.

    These are 'armchair' suggestions, just ideas to examine.

    Murray
     
  22. Guillaume Zuili

    Guillaume Zuili Subscriber

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    I had the same problem few years ago. I had just changed the bulb on my Durst 138. As bulbs were phased out I had a different one and stronger. That circle came up. Tried to smooth it with by putting some opaq glass in between. It worked at first but as soon as you expose long enough that circle was coming back.
    This is why I switched all my enlargers with cold light. No more weird circle or illumination.
     
  23. Peter Williams

    Peter Williams Member

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    I narrowed the problem down to the lens mounting ring. This lens came with a silver colored mounting ring and it was reflecting inside the lens cone and creating the ring. So now I have a print of that negative without and ring. I was very pleased that I finally figured it out (with all of your help) and she looks me in the eye and says, "I liked it better with the ring."