Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,231   Posts: 1,532,880   Online: 1035
      
Results 1 to 3 of 3
  1. #1

    Join Date
    Apr 2008
    Shooter
    4x5 Format
    Posts
    57
    Images
    1

    Densitometer: alternative calibration targets

    I acquired an X-Rite 811 densitometer and their website wants $110 for the transmission and reflection calibration targets. The reflection target looks nothing more than white/black/grey dots on a small card. The transmission is a 4 step wedge (I assume transparency/slide).

    I want to use Stouffer's 21 step targets (Reflection and Transmission), but which 3 or 4 would I use for calibration. I like the idea of the Stouffer products since they have other uses and they are $6.55 each.
    Robland - Seattle area

    Insert "catch phrase" here...

  2. #2
    L Gebhardt's Avatar
    Join Date
    Jun 2003
    Location
    NH - Live Free or Die
    Shooter
    Large Format
    Posts
    1,675
    Blog Entries
    1
    Images
    18
    The reflection target is actually a metal plate coated with enamel. So I can see how it's expensive. Any item with approximately the correct values should work. On my 810 I can input what the calibration targets' values are.

    Each color channel varies by a few points but, for reflection they are about:

    White .08
    Grey .95
    black 1.8


    The transmission target is:
    Linearity 4 3.7
    Cal HI 3.0
    Linearity 2 1.47
    Linearity 1 .23

    Those values might help you in finding a suitable substitute.

  3. #3
    Mike Wilde's Avatar
    Join Date
    Aug 2006
    Location
    Misissauaga Canada
    Shooter
    Multi Format
    Posts
    2,939
    Images
    29
    Stouffer 21 step is half a stop scale, Dlog=0.15 per step, so you can use the first clearsectio as base fog, and zero on that, and then verify that , say 4 setps in you are reading close to .60. Stoffer sell calibrated step wedges, but is it really that important how precise you are?

    I don' have a reflective densitometer ( I was freely given an old TD-504) When I am calibrating for alt processe, etc., I contact print the step wedge onto a sample piece of sensitised material, then process and dry it. Using a portion of the un-exposed but sensitized material, I zero the transmission unit, and read through the paper base to get how linera the step wedge is. This gives me a good idea of what contrast index that negatives should be made to to print well onto any particular alt process.
    my real name, imagine that.



 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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