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  1. #21

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    Quote Originally Posted by ic-racer View Post
    The burn is on the edges only. Center exposure time is the same on each.
    I understand. What I am saying is that I would not do the burn first, in order to make the center more consistent print to print. I was asking why someone would do the burn first.

    As for the lamp heat affecting exposure, if I remember your IR measurements graph, it only takes noticeable effect on density in exposures of some time...far longer than any exposures I have made except with lith printing or very large prints from fairly dense negs.

    Thank you for your testing, BTW. It is quite interesting info. What did you use to determine the reduction in lamp brightness at a certain exposure time?
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  2. #22
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    Quote Originally Posted by 2F/2F View Post
    I understand. What I am saying is that I would not do the burn first, in order to make the center more consistent print to print. I was asking why someone would do the burn first.
    Yes, I usually don't either, but (I didn't go in to detail in the example photograph) but it was a split grade exposure, so I had an extensive burn before the second main exposure. (I did not do the burn on the test print, thus the change in lamp output from test-print to final print).

    As for the lamp heat affecting exposure, if I remember your IR measurements graph, it only takes noticeable effect on density in exposures of some time...far longer than any exposures I have made except with lith printing or very large prints from fairly dense negs.
    Exactly, I agree, and I think a compensating timer or special control unit is not a nesscessity.

    Thank you for your testing, BTW. It is quite interesting info. What did you use to determine the reduction in lamp brightness at a certain exposure time?
    Simply put a light meter on the baseboard aimed up at the enlarger lens. Safelights off, of course.

    In 30 years I had never encountered anything like this, so I wanted to share the experience. I have never seen a graph like I posted in any discussion of coldlights, but it IS a characteristic response of these lamps.

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