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  1. #11

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    Quote Originally Posted by Vaughn View Post
    I would heat the negative up in the enlarger of about a minute (by turning the lamp on) and let the negative "pop". I then would start my exposure. I would keep the enlarger on during the 15 minutes or so of burning.

    Others use a glass negative carrier.

    The 10 hr exposure:

    No test strips. My average exposure time was two hours. This particular neg had a large area of high density (sun on granite -- I could barely make out detail in the highlights with an intense light behind it) so I just exposed a bit more than a stop more -- 6 hours. The print looked very good, but I though I would add just a little more than a half-stop more exposure to see what it looked like...ten hours.

    You have very thick negatives if your average time is 2 hours........

  2. #12
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    Quote Originally Posted by dreamingartemis View Post
    Hi,
    , to my horror when the image showed up, while one side was properly exposure but the right side wasn't,
    I always establish my exposure plan with not so large paper, mostly 18x24 cm². Times are much shorter then. Of course I need a test strip for the large paper for finding the exposure time and slight corrections of contrast, but the relations between the image parts remain the same, if I use the same type of paper. If you'd use identical paper, that means, if you cut a large format int smaller ones, you don't need to correct the contrast.
    ---
    Uwe Pilz

  3. #13

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    Quote Originally Posted by NormG View Post
    Do these long exposure times have any effect on the negative in the carrier? The reason i ask is that i recall somebody once commenting on an out of focus print because the negative warped due to the heat from the lamp.
    In my opinion unless there is zero heat buildup at the negative stage over such a long period, a glass carrier is necessary. I would not rely on preheating the negative. At a minimum I suggest a top glass carrier (glass only on top of the negative) if you don't want to use a full glass carrier. Negative deformation from heat is mostly in the upward direction so a top glass can help quite a lot.

    An important benefit to using a glass carrier is it often enables you to use a larger aperture on the enlarging lens, which can significantly shorten the exposure time.

    Even with a glass carrier, I would do some tests without a negative just to see how much heat buildup there is during a very long exposure. In many setups, even with heat absorbing glass etc, tremendous amounts of heat can build up at the negative stage and you don't want to damage anything.

  4. #14
    Andrew K's Avatar
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    Quote Originally Posted by keithwms View Post
    Well why not first dupe the thick neg onto something much more sensitive e.g. film. The problem here is that you have an ~ISO 3 material. You can dupe it to film and rate that film at whatever you please.
    In my case I didn't do dupe positives because I was printing 100 year old wet plate negs ...and the tonal range on unfiltered multigrade paper was incredible....
    A camera is only a black box with a hole in it....

    my blog...some film, some digital http://andrewk1965.wordpress.com/

  5. #15
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    Quote Originally Posted by NormG View Post
    Do these long exposure times have any effect on the negative in the carrier? The reason i ask is that i recall somebody once commenting on an out of focus print because the negative warped due to the heat from the lamp.
    it can depending on your enlarger. If I'm using a condensor enlarger I tend to use at least a anti-newton glass above the neg (which seems to prevent popping). On a diffusion enlarger (either an enlarger with a color head - usually a De Vere 504 or Chromega, or an enlarger fitted with a Ilford Multigrade 500 head) I've always used glassless carriers and not had any neg popping problems with long exposures

    Then again if I were printing anything bigger than 6x7, or a single negative I would probably use a glass carrier
    A camera is only a black box with a hole in it....

    my blog...some film, some digital http://andrewk1965.wordpress.com/

  6. #16

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    Quote Originally Posted by piu58 View Post
    I always establish my exposure plan with not so large paper, mostly 18x24 cm². Times are much shorter then. Of course I need a test strip for the large paper for finding the exposure time and slight corrections of contrast, but the relations between the image parts remain the same, if I use the same type of paper. If you'd use identical paper, that means, if you cut a large format int smaller ones, you don't need to correct the contrast.
    Yeah, that's what I'm doing now because of this photo. First I would look at it on the lighttable, if it looks thick, prepare up square pieces from one large piece, then place each small piece of squares on the area or region of the photos that matters to the overall composition. Guess the exposure first base on past experience, develop and if it doesn't look right, try again. Do this till it looks right, only then do a final print.....

    But even with all that, it's still all art and not science since mistakes can still happen as I learned last night when I again wasted some 9.5x12 inch FB paper

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