Corner burn not looking right - what am I doing wrong?

Discussion in 'Enlarging' started by tkamiya, Jul 17, 2011.

  1. tkamiya

    tkamiya Member

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    I'm fairly convinced I am doing this wrong and my problem is at a fundamental level. Please help if you can tell what I am doing wrong. In short, I cannot get the corner burning to look the way I want.

    Posted here is an upper 4x6" square of my 8x10 print. Paper is Ilford MGIV FB and film used was Delta 3200. (which isn't important for this discussion but explains why it's so grainy)

    Base exposure was done at grade 2.5 filter and for 12 seconds.
    Burning of the corner was done with grade 00 filter and for 24 seconds with me moving a card back and forth in the range indicated for the entire time. For your reference black rectangle on the back is actually black and the white card behind is white. (for density reference) Neck part is obviously over exposed.

    There are two problems.

    Please note how far I moved the burn-in card and compare it with how abruptly and in short distance the density changes. This isn't what I wanted. I wanted the change to be gradual across the span indicated.

    Please also note, the upper corner didn't reach max black. I wanted it to.... but if I lengthened exposure time to 36 seconds, it still didn't reach black. It just got a little darker and the abrupt transition mentioned above became more obvious.

    If I used the same filter as the base exposure for the burn-in, it was more closer to what I wanted in terms of density change and the maximum black, but it made the vertical line you see in the left edge more obvious. I didn't want that either.

    So I ask... what am I doing wrong?

    What I'm really after is for the corner to be nearly completely black, and gradation to start at the upper line and smoothly transition to the base exposure at the bottom line.
     

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  2. ic-racer

    ic-racer Member

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    I'd just burn with the base filter 2.5. In my own opinion situations where a different filter is needed for a burn are very very infrequent. Burn with the 00 filter just makes the areas that would be white, now dark gray. It won't make blacks blacker.
     
  3. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Have you tried edge burning? Maybe it's not the effect you're after, but it often looks more natural than just burning the corners. On an 8x10" print, you might burn a strip about 1.5" along each edge in sequence, so the corners overlap and blend into the burn along the edges.
     
  4. tkamiya

    tkamiya Member

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    If I don't figure out why the transition area is so abrupt and short, edge burning will run into the same problem.... in fact, when I tried it, it did!
     
  5. bdial

    bdial Subscriber

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    To get the corner black, you'll need more time and I'm in agreement with ic-racer on the filtration. You may need to hold the vertical dark area back some to keep it from getting too much density if it's too prominate in your same filter burn. To do that dodge part of it during the base exposure so that the burn gets it to where you want to be.
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    In that case, it's just where you're placing and how you're moving the card. Hold it closer to the edge and experiment with the speed.
     
  7. tkamiya

    tkamiya Member

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    I moved the card at a constant speed, back and forth. Perhaps taking 2 seconds for the complete pass. I thought that will cause the density to build up across this entire path evenly and smoothly. How would you advise I change this method?
     
  8. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Start the motion about 25% in from the burn area and just move the card over the remaining 75%, maybe with a little faster motion. Experiment.

    If you want the darkest part darker, you can also increase the general burn time.
     
  9. Worker 11811

    Worker 11811 Member

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    Is the beam spread on your enlarger properly set?

    If the lamp isn't focused properly you could have hot spots or dim corners in the field of illumination. At one exposure or contrast setting this could go unnoticed but could be exacerbated when you make timing or contrast changes.

    Further, if the lamp is out of alignment, this could be the reason you have to burn the corners in the first place.

    On my Beseler, there is an adjustment for beam spread which is changed for negatives of different formats. For instance, a 120 format negative uses one setting while a 35 mm negative uses another, longer, setting. I sometimes forget to change settings or, on occasion, find it set wrong by accident.

    Even if this is not the problem in your case it is worthwhile to check to see if your light field is flat and adjust or repair your lamp housing if necessary.
     
  10. ooze

    ooze Member

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    Moving the card at *constant* speed across the burn-in range is not how I prefer to do it. I move it faster around the inner line, and slow down considerably as I move outward.
     
  11. polyglot

    polyglot Member

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    The transition is abrupt because you're moving the card uniformly. The uniformity means that you get a greater relative change in density in the light areas than the dark:
    - outside the burn, you have 12s
    - in the middle of the burn, you have 24s
    - at the edge, you have 36s

    So the middle of the burn is twice as dense as the unburnt, while the outside corner is only 1/3 denser than the middle of the burn. The closer to the unburnt area you get, the steeper the apparent density gradient becomes.

    The next thing that's making it MUCH worse is that you're burning with #00 a print made at #2.5. At #2.5, your unburnt highlight has practically zero density, but the #00 will burn the highlights in REALLY quickly. So in terms of the density achieved on the paper, you're talking more like 6s of base exposure and 24s of burning. So the inner bit of gradient is 6s -> 18s (factor of three) while the outer bit of gradient is 18s -> 30s (factor of < 2). I almost never burn at a lower grade, I generally only burn at the same or higher grades.
     
  12. Bob Carnie

    Bob Carnie Subscriber

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    00 filter is the wrong one I agree
    Also the corners are not sharp like the area closer to the head, are you using a glass carrier?
    for Corner burns I never use a card. I use my hands , they can be manipulated around the heads much easier and basically I am not trying to make a gradient rather burn the whole area you are illustrating and then just add a punch to the corners.
    If you are trying to get black maybe a higher contrast filter for part of the time.
    When burning in I have my hands about 1/3 down from lens to easel .
    Pretend you are cupping your hand and moving your fingers you can get different shapes.

     
  13. tkamiya

    tkamiya Member

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    Bob,

    No, I am not using glass carrier. The image is out-of-focus at corners as I shot this wide open (80mm 645 at f/2.8) and focus is on person. I'll have to try close to the lens and using my hands - that will probably help making the edges softer. Thank you for your advise.
     
  14. tkamiya

    tkamiya Member

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    When would one use #00 for burning in then? I was under the impression that when burning areas where details shouldn't be there, using 0 or 00 was sort of the standard.
     
  15. Bob Carnie

    Bob Carnie Subscriber

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    You need to look closer at the edges, even if your DOF is soft behind the subject , you Should see sharp grain.

    Look at Anton Corbjin work, its all about the sharp out of focus areas.
    Stopping down the lens will not help, make the jump to glass carriers and you will be happy.
     
  16. Bob Carnie

    Bob Carnie Subscriber

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    I use the 00 for highlight regions only, nowhere else.
    On your sample look at the grey tone , that is because of the 00 which is not helping you.