Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,545   Posts: 1,572,844   Online: 1020
      
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 32

Thread: Kodak Techpan

  1. #21

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    Tom,
    Thank you for your work and for reporting the results. This is interesting. It would seem that the hydroquinone developer does not support shadow separation as well as the Pyrocat developer. What I am wondering, in light of the initial hydroquinone developer density reading (.03) is what the film base plus fog reading was for the film. It would appear that the hydroquinone developer also effects film speed. What are your thoughts on this?

  2. #22

    Join Date
    Mar 2004
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    3,879
    Images
    11
    Thank you Donald.
    You are correct.
    Both hydroquinone and catechol, when used as single component developers like the ones I tested, produce overall and proportional stain, but do not produce the shadow separation that they produce when combined with phenidone (with the resulting additive effects). An additional consequence is a reduction in effective film speed. Another consequence is a reduction in developer activity.

    The result with Kodak Tech Pan is an EI of about 25 and a D Log E curve like the one POTA produces.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  3. #23

    Join Date
    Mar 2004
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    3,879
    Images
    11
    Donald:
    The Visual Channel base plus fog was 0.19 and the Blue Channel base plus fog was .20 (as I recall - I will go back and double check the numbers).

    The film was fresh Kodak Tech Pan 120 Roll with a 2005 expiration date.

    My Stand Development procedure: In a filled tank with 20 seconds of initial gentle torus inversion agitation. No agitation at all for the remainder of the 20 minutes.

    Rinse (no stop bath) was for 1 minute in 18 megaohm deionized water. Fixer was TF-4 (alkaline - non hardening) for 4 minutes.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  4. #24

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    Quote Originally Posted by Tom Hoskinson
    Donald:
    The Visual Channel base plus fog was 0.19 and the Blue Channel base plus fog was .20 (as I recall - I will go back and double check the numbers).

    The film was fresh Kodak Tech Pan 120 Roll with a 2005 expiration date.

    My Stand Development procedure: In a filled tank with 20 seconds of initial gentle torus inversion agitation. No agitation at all for the remainder of the 20 minutes.

    Rinse (no stop bath) was for 1 minute in 18 megaohm deionized water. Fixer was TF-4 (alkaline - non hardening) for 4 minutes.
    Tom,

    I guess that I am not tracking with you here. When I look at the first two density levels that you reported in your initial visual and blue channel comparisons for hydroquinone and for catechol the densities are below what you said FB+fog are. What am I missing here?

  5. #25

    Join Date
    Mar 2004
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    3,879
    Images
    11
    Donald:
    The densities I posted are the delta densities over the base + fog.

    My densitometer (a Macbeth Color Densitometer) has a function that, given a base + fog sample, measures the density, stores it, then calculates and displays the deltas for additional samples until the function is reset. I did separate base + fog measurements for both the visual channel and the blue channel.

    Sorry for the confusion.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  6. #26
    Ka
    Ka is offline

    Join Date
    Feb 2004
    Location
    New York
    Shooter
    Medium Format
    Posts
    215
    Could you chem mixing-creating types refer me to some books so I might be able to:

    1) understand about what you are talking, and
    2) mix my own, as needed, fine-tuning the mix for the job before me.

    At present, I unscrew the bottle, and dilute with the prescribed ratio of water. Even my 4-year old daughter can mix her juice out with water. I should very much like to know more... just don't know where to start.

    Thanks.

  7. #27

    Join Date
    Dec 2002
    Shooter
    Large Format
    Posts
    6,242
    The Darkroom Cookbook by Steve Anchell and Troop is a good book that discusses chemistry, formulations, and considerations.

    Insofar as formulations that are commonly used...you can find the recipes for Smith's amidol and ABC Pyro on the Azo Forum www.michaelandpaula.com

    Another site that has formulations for developers posted is www.unblinkingeye.com

    Beyond that you can find a lot of different photo formulations online by doing a google search for photo chemistry formulas.

    If you want an understanding of film density and paper reflection density then the Ansel Adams series (The Negative and The Print are good entry level texts.

    Another excellent text is Beyond The Zone System by Phil Davis. A dry and highly technical work but very good.

    That probably will keep you busy for a little while. Good luck.

  8. #28
    Ka
    Ka is offline

    Join Date
    Feb 2004
    Location
    New York
    Shooter
    Medium Format
    Posts
    215
    thanks

  9. #29
    gainer's Avatar
    Join Date
    Sep 2002
    Posts
    3,726
    Images
    2
    You might also look at the Mar/Apr issue of Photo Techniques magazine for the article "The Role of Antifreeze in Photographic Science" for some interesting staining developers you can mix yourself.
    Gadget Gainer

  10. #30

    Join Date
    Mar 2004
    Location
    Southern California
    Shooter
    Multi Format
    Posts
    3,879
    Images
    11
    Hi Patrick.

    Catechol/Ethylene Glycol and Hydroquinone/Ethylene Glycol worked just fine. No sulfites, no bromide. Plenty of proportional stain & tanning with both.
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

Page 3 of 4 FirstFirst 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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