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Thread: densitometers

  1. #1

    Join Date
    Sep 2004
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    La Quinta, CA
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    394

    densitometers

    I've finally taken the plung to try Pyro developing for B/W film. After a lot of reading and research, I 've found out that my B/W densitometer isn't right for Pyro stained negatives. I've been looking into color densitometers and have found a lot of mention to the X-Rite 810 - and there seems to be a lot of them out there for sale. However, today I stumbled across an old View Camera Magazine (March/April 2003) article written by Bob Herbst where he says that to get true readings of Pyro Stained negatives, you need a densitometer that also has a UV channel. He goes on to say that about the only one out there that has this capability is the X-Rite 361T.

    What are all you Pyro veterans out there using, and is the 361T really the only that can do this? Before I buy a second densitometer, I want to know for sure whether it will work adequately when it comes to Pyro Stained negatives. Have any of you who may have this model done comparisons similar to Bob between the Blue Channel and the UV Channel readings. If so, were your results similar to those in Bob's article? What if I get a standard color densitometer and just add 20% to the density readings from the Blue Channel? That is about the differences in the readings in the article.

  2. #2

    densitometers

    You need the UV capability if you are planning to do alternative processes like pt/pd. When Herbst wrote that article the 361T became very popular and now they go for $300 to $400 if you can find the 369T (which is what I have) you can probably get it a lot cheaper since it was supposed to be for azo (not the paper) and circuit boards....it works just like the 361T.

    If you dont plan to do any alt processes then any color densitometer with a blue channel will work to simulate paper emulsions.

  3. #3

    densitometers

    Hi Dan,

    I have done considerable testing on pyro negatives. All readings with a calibrated 810. Using Bob's method, where he investigated the staining character of the pyro negative with blue channel readings, I can relay the following information. Determine time for max black on AZO grade 2. Using a pyro negative ("stained tablet": expose tablet on negative developed in pyro) and a standard tablet, the following density readings result in 0.04 over paper base (hint of gray):

    blue channel for pyro negatives:

    ABC = 1.34

    pyrocatHD = 1.4

    WD2D = 1.53

    visual for tablet: 1.9

    Notice the densities are not an exposure scale but a density to achieve a hint of gray. Were the blue channel readings of the pyro negatives close to the visual reading on the tablet (1.9 or thereabout) then I would say the blue channel reading did approximate the effective density needed for AZO printing. They do not! In order to use the blue channel readings on the pyro negative one must know the density range needed from a pyro negative as measured in blue channel. I have had some disagreement on the concept of using a "stained tablet" for determining the density range. I'll maintain the toes and shoulders have nothing to do with a single density reading that produces a given result on paper at a standard print time. All of the above can be done with visual only. The numbers on the pyro negative would be appx 0.25 less. So its a scale difference. If a corresponding UV reading were around 1.9 then I would say it is a perfect pick. I have no experience there. As Jorge and others will tell you the UV readings work perfect for alt printers

    best of luck

  4. #4

    Join Date
    Sep 2004
    Location
    La Quinta, CA
    Posts
    394

    densitometers

    Jorge and Phil,

    Thanks for the "expert" advice - it's just the sort of thing that I need. Since you both have different approaches regarding the Densitometers, I'll have to do some more research to decide which way I may want to go. My ultimate decision may hinge on the availability (or inavailability) of the 361T and 369T densitometers. The 810's seem to be readily available on E-bay right now.

    Phil - your approach seems very intesting and somewhat complicated to me right now. I would hope that if I go the route of the 810, I could contact you later with any questions on your testing experiences.

    Thanks to both of you.

  5. #5

    densitometers

    Dan,

    I would like to get a UV reading densitometer also. Just not sure how much I want to spend. I have learned a lot from using a densitometer. But for my AZO work the "visual" tests and development by inspection has been as rewarding or more!

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