Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,752   Posts: 1,515,906   Online: 1099
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 22
  1. #1
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,103

    True or False... (kind of a trick question, just for fun)

    Two prints with identical total base exposure time (same enlarger, negative, paper, lens etc.). The print with an extensive 'burn-in' around the edges can have a LIGHTER center.
    Last edited by ic-racer; 08-19-2008 at 06:19 PM. Click to view previous post history.

  2. #2

    Join Date
    Apr 2007
    Location
    Nanaimo, British Columbia
    Shooter
    35mm
    Posts
    907
    Images
    4
    True or false? Yes.

    If you did the base exposures and followed that with the burning in, then the center of the burned-in print would be identical to the non-burned in, but appear lighter because of the darker edges. So the answer would be false.

    If the edges of the burned-in print were burned in while making the base exposure on that print then the center would be lighter because you'd have been dodging it while burning in the edges on the base exposure, so the answer would be true.

  3. #3
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,103
    Total exposure time to the center of each print is identical.

  4. #4
    Steve Smith's Avatar
    Join Date
    May 2006
    Location
    Ryde, Isle of Wight
    Shooter
    Medium Format
    Posts
    8,530
    Images
    122
    It's definitely true or false.

  5. #5
    Robert Kerwin's Avatar
    Join Date
    Oct 2005
    Location
    Albuquerque, NM, USA
    Shooter
    Medium Format
    Posts
    206
    Images
    10
    Quote Originally Posted by ic-racer View Post
    Two prints with identical total base exposure (same enlarger, negative, paper, lens etc.). The print with an extensive 'burn-in' around the edges can have a LIGHTER center.
    Lighter than what? The center of the other print? Take a knife and cut out the two centers, then compare them side by side on a sheet of white mat board. Better yet, have someone else do it for you and not tell you which patch came from which print.
    "Photograph more, worry less"

  6. #6
    eric's Avatar
    Join Date
    Sep 2002
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    1,586
    Images
    55
    E, Both A and C are correct.
    or
    F. Neither B or D is correct.
    G. All the above is correct.
    ...this is how I got through college and look at me now!

  7. #7
    scootermm's Avatar
    Join Date
    Jun 2004
    Location
    Austin, TX
    Shooter
    ULarge Format
    Posts
    1,867
    Images
    235
    Quote Originally Posted by eric View Post
    E, Both A and C are correct.
    or
    F. Neither B or D is correct.
    G. All the above is correct.
    ...this is how I got through college and look at me now!

    how about...
    H. The question is dumb.

    Nigel Tufnel: It's like, how much more black could this be? and the answer is none.
    None more black.

  8. #8
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    All questions are dumb. The people who ask them are at least smart enough to ask. Sometimes it boils down to asking the right people to answer dumb questions.

    You could take two pieces of white drawing paper that look to be the same brightness and paint a black border on one of them. See how the width of the border changes the apparent brightness of the central portion. A change in the brightness of any part of the field of view can cause a change in the adapation level of the eye. This adaptation has two mechanisms: the obvious one is the iris, which has a rapid response but a limited range. The other is chemical, more like printing out paper. You see that if there is a small light leak in your darkroom. At first you can see nothing when the light goes out. After a while, you begin to wonder if you should have loaded that developing tank without a changing bag.

    The eye has a logarithmic response to change of illumination, so that the just noticeable change is nearly constant over a wide range. For that reason, brightness comparisons should be done side by side, not one after the other.

    It's a complex subject over which I spent many hours during my years of study of human factors at NACA-NASA.
    Gadget Gainer

  9. #9
    2F/2F's Avatar
    Join Date
    Apr 2008
    Location
    Los Angeles, CA
    Shooter
    Multi Format
    Posts
    8,008
    Images
    4
    With identical processing, and exactly the same exposure, False. However, both of these things are difficult to get exact. Are you actually comparing the center of one to the center of the other? Or does it just look brighter on the burned one because you are comparing it to the edges?
    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)

  10. #10

    Join Date
    May 2005
    Location
    Woonsocket, RI USA
    Shooter
    35mm
    Posts
    2,725
    They could be different because of reciprocity effects, if the lens aperture or ND filtration lengthened the exposure time significantly. There could also be effects based on filtration for contrast on VC paper, but IMHO that would be violating the spirit of the question.

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin