Page 17 of 17 FirstFirst ... 7151617
Results 161 to 167 of 167

Thread: Film test results

  1. #161

    Join Date
    Dec 2009
    Location
    Pacifica, CA
    Posts
    1,492

    Re: Film test results

    Note... The Zone II is probably 0.40. While the model does try to define Zone I. So 1.45 isn't the aim.

  2. #162

    Join Date
    Jul 2008
    Location
    Los Angeles
    Posts
    212

    Re: Film test results

    Quote Originally Posted by Bill Burk View Post
    And we haven't introduced yet... enlarger flare.

    And we haven't introduced yet the idea that you want to overrun the paper LER a little.
    Most of my paper curves incorporate flare. Instead of contacting the step tablet, I usually enlarge the test. I don't want to have to add more quadrants.

    From a tone reproduction basis, Jones found, “for the soft papers, the density scales of the negative (DR) should in most cases exceed the sensitometric exposure scale of the paper (LER), whereas, for the hard papers, the density scales of the negatives should in most cases be less than the sensitometric exposure scale of the paper (LER).” I've factored in this concept into my developmental model.

  3. #163

    Join Date
    Jul 2008
    Location
    Los Angeles
    Posts
    212

    Re: Film test results

    Bill, we both forgot to mention that speeds derived from using the fixed density point of 0.10 over Fb+f are only accurate for "normal" using the ISO standard's contrast parameters.

  4. #164

    Join Date
    Dec 2009
    Location
    Pacifica, CA
    Posts
    1,492

    Re: Film test results

    True, we didn't get into that.

    I take comfort knowing the Delta-X criterion explains that speed doesn't change significantly with changes in development time, when you look at how little the 0.3 Gradient point moves with changes in development time.

    And so I understand the speed I find with the ISO contrast parameters, might be OK as the benchmark for that film/developer combination - regardless how long I plan to develop it. Though I still mark my graphs with 0.10 speed points, I appreciate that speed point doesn't have to be 0.10

  5. #165

    Join Date
    Jul 2008
    Location
    Los Angeles
    Posts
    212

    Re: Film test results

    Quote Originally Posted by Bill Burk View Post
    True, we didn't get into that.

    I take comfort knowing the Delta-X criterion explains that speed doesn't change significantly with changes in development time, when you look at how little the 0.3 Gradient point moves with changes in development time.

    And so I understand the speed I find with the ISO contrast parameters, might be OK as the benchmark for that film/developer combination - regardless how long I plan to develop it. Though I still mark my graphs with 0.10 speed points, I appreciate that speed point doesn't have to be 0.10
    I brought up Delta-X as a question of the practicality of doing a speed test for most people. It's unrealistic to expect valid speed results without a sensitometer and proper methodology. The best that can be expected is comparative results between films or developers. I believe time is better spent first understanding what film speed is and isn't, picking an EI that works with your personal shooting and metering style, and focusing the testing instead on contrast determination. The ISO speed is a valid speed that can be used to base a personal EI. A test that doesn't produce a reliable and verifiable result isn't worth doing.

  6. #166

    Join Date
    Dec 2009
    Location
    Pacifica, CA
    Posts
    1,492

    Re: Film test results

    I am with you 100% that the best tests an individual can do successfully with a minimum of effort... is to determine contrast for development times.

    Mario can tell us if the film speed tests were helpful... for the purpose of learning.

    One thing I learned here was the value of checking shutters (which I always used at nominal speeds before this exercise).

  7. #167
    Rafal Lukawiecki's Avatar
    Join Date
    Feb 2006
    Location
    Co. Wicklow, Ireland
    Posts
    138

    Re: Film test results

    Quote Originally Posted by Stephen Benskin View Post
    I believe time is better spent first understanding what film speed is and isn't, picking an EI that works with your personal shooting and metering style, and focusing the testing instead on contrast determination.
    Amen. I came to the same conclusion having dabbled in practical sensitometry over the last three years. The reasoning, for me, is driven by my experience that adjusting small-area, local ("micro") contrast is much harder under the enlarger, than making larger sweeping changes, made easy with VC filtration, while film latitude in exposure tolerance is phenomenal, nowadays, for the films I used, Delta, HP5+ and Tri-X.

    All in all, my main use of the film testing/ZS/sensitometry is for the contrast control of the things I cannot (yet?) easily control under the enlarger, even with VC. In practice, it means that I'd no longer indicate N, N+1 etc on the basis of the overall scene range, which I know I can control by other means (VC) but almost always by the localised needs in complex areas of the scene, which I expect would give me grief while dodging, burning, or masking.

    EI is almost a secondary concern to me, as long as it is safe enough to have shadow detail on the film.
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

Similar Threads

  1. Aardenburg archival test results....?
    By Kirk Gittings in forum Digital Hardware
    Replies: 10
    Last Post: 26-Sep-2010, 10:27
  2. Film Test Results
    By Tony Flora in forum Darkroom: Film, Processing & Printing
    Replies: 22
    Last Post: 6-Oct-2008, 11:24
  3. Some lightfastness test results
    By paulr in forum Darkroom: Film, Processing & Printing
    Replies: 5
    Last Post: 29-Aug-2006, 09:48
  4. Rollei infrared film test results
    By Jonathan Brewer in forum Lenses & Lens Accessories
    Replies: 2
    Last Post: 27-Jul-2006, 22:35

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •