Cause of light corners?

Discussion in 'Enlarging' started by kitty, May 20, 2005.

  1. kitty

    kitty Member

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    Hello,
    I'm hoping somebody can offer some possible causes of the light corners I get in all my prints. When I print, regardless of which negative I'm using, all four corners are much lighter than the center of my print. If it's not an area that's going to be covered by a matt, I spend extra time burning in those areas, but this seems like a lot of extra work.
    Any ideas of what could be causing this? I'm new to b&w photography, so please don't hesitate to state the obvious. I'm printing on ilford multigrade IV, from 35 mm negatives. I"m thinking it's not in the negatives?? Any ideas or suggestions are greatly appreciated.
     
  2. Clueless

    Clueless Member

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    Not really unusual, but there are many considerations that influence the issue. So, it would be helpful to identify your enlarger, its light system, lense(s), the cleanliness of same, etc.
     
  3. chuck94022

    chuck94022 Subscriber

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    It seems most likely that you are getting light fall-off (uneven light) in the corners. You might try projecting light through your negative carrier onto the easel without a negative in place. Focus so that the edges of the negative carrier are reasonably sharp. Check to see if you are getting even light out to the corners.

    If not, you can check your enlarger to see if you have some sort of disruption of the light path, but it could be that your particular enlarger doesn't cover the full 35mm image.

    Clueless is correct though, provide more details and perhaps someone can help you with your specific case.
     
  4. kitty

    kitty Member

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    It's not my own enlarger, it's in the school's darkroom, but I always use the same enlarger. All I can say for sure is that it's a bessler enlarger, I think the 67c model. I have no idea on the lens or light system. As for cleanliness, I always have to blow/brush dust and lint from my negatives, so I'd say not so clean. The only other comment I can make is that a few weeks ago, the bulb burnt out while I was printing. The instructor replaced the bulb a few days later. I can't say for certain if I was getting these light corners before that or not, but it maybe seems like I wasn't.

    However, having gotten many of the small white specks from dust/lint, I can say this is different. These are large areas in each corner that start from being very light, almost white, with a smooth gradual gradation darker to the some tone as the rest of my print. The majority of the print is fine, it just fades to very light in the four corners. These are not sharp square light corners, but rather more rounded corners. Much like vignetting, except going to light instead of dark.
     
  5. Paul Sorensen

    Paul Sorensen Member

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    I will second what Chuck says but add that you need to adjust the top bellows. If you do that, you will see that you can make the image circle larger or smaller. Just make sure that it gets big enough so that the corners are as bright as the center. I am assuming that you are using 35mm film. If you are using 120 film, you possibly also need to ask the instructor for a 75mm or 80mm lens as opposed to 50mm.

    Good luck,

    Paul.
     
  6. Jon Shiu

    Jon Shiu Subscriber

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    I would say work with your instructor to solve the problem. Have him/her check the position of the condensers (there is a diagram on the back of the sliding front plate on the 67c. Sometimes the below lens filter holder blocks part of the light, but not usually on all 4 corners at the same time. If it is a 23C, then adjust the condensers to the correct position for 35mm.

    Jon
     
  7. Christopher Colley

    Christopher Colley Member

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    If you are using under-lens contrast filters you may want to try and move the filter out of the way, sometimes these can cause the problem you are describing, also, sometimes these under-the-lens contrast filter holders are very loose...... on one enlarger i used all i had to do to avoid the light fall off was to push the filter holder up towards the lens, making the edges of the filter go out of the projected image area. you may want to check for this!