Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,571   Posts: 1,545,551   Online: 1079
      
Page 1 of 7 1234567 LastLast
Results 1 to 10 of 62
  1. #1
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,223

    The Great Sensitometer Shootout....

    I have a number of sensitometers to compare.
    Each is a different construction.

    EG&G: Xenon flash
    Wejex: incandescent lamp
    ESECO Speedmaster: green LED
    ESECO Speedmaster: blue LED

    I'm going to run some step wedges at different development times and see if they all produce curves that can give reasonable information about development time.

    The LED sensitometers are frequently available on ebay and I hope to provide some information on the utility of those devices in making control strips for the B&W home darkroom.

    Then null hypothesis here is that the color of light and time of exposure will have very little effect on the films response to changes in development times.




    Last edited by ic-racer; 10-13-2012 at 04:17 PM. Click to view previous post history.

  2. #2

    Join Date
    Jul 2011
    Shooter
    35mm
    Posts
    27
    My old toys . Most people just eyeball it. I love how a good meter saves so much time.
    And you can't lie to yourself.

  3. #3
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,223
    Two strips of Tri-X 35mm film were exposed using the 4 devices.
    The first strip was processed for 5 minutes.
    The second strip was processed for 7 minutes.

    The the resulting negatives were read with a calibrated Tobias densitometer and plotted in Microsoft Excel. The slope of the straight line portion of the curves was obtained with a linear regression analysis.
    Last edited by ic-racer; 10-13-2012 at 11:23 PM. Click to view previous post history.

  4. #4
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,223


    Exposure on X-axis, Negative Density on Y axis.
    Note: Colors of lines change (thank your Bill Gates).
    Last edited by ic-racer; 10-13-2012 at 11:31 PM. Click to view previous post history.

  5. #5
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,223

    Resulting slopes.

  6. #6
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,223

    Last edited by ic-racer; 10-13-2012 at 11:39 PM. Click to view previous post history.

  7. #7
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,223
    Conclusion:
    The color of sensitometer light does not affect Tri-X response to changes in development time.

  8. #8
    michaelbsc's Avatar
    Join Date
    Dec 2007
    Location
    South Carolina
    Shooter
    Multi Format
    Posts
    2,106
    Images
    5

    The Great Sensitometer Shootout....

    Quote Originally Posted by ic-racer View Post
    Conclusion:
    The color of sensitometer light does not affect Tri-X response to changes in development time.
    Well done, sir!
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  9. #9

    Join Date
    Mar 2009
    Location
    Vancouver, WA USA
    Shooter
    35mm
    Posts
    303
    This is great. Thanks for taking the time to to do a controlled test.

    Knowing that the type of sensitometer doesn't make a real difference, I might abandon my plans to build my own, and see what I can scratch up used.

    Could you post the entire curves (toes and shoulders)?

    --Greg

  10. #10
    Rafal Lukawiecki's Avatar
    Join Date
    Feb 2006
    Location
    Co. Wicklow, Ireland
    Shooter
    Multi Format
    Posts
    737
    Thanks, IC. This is very useful, considering my recent barrage of sensitometer-related questions on other threads. I suppose other films should be similar in ignoring the sensitometer light source design, but this is only a hypothesis for now.

    Now, I would like either of those, please.
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

Page 1 of 7 1234567 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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