Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 70,708   Posts: 1,548,552   Online: 1170
      
Page 9 of 11 FirstFirst ... 34567891011 LastLast
Results 81 to 90 of 103
  1. #81
    AndreasT's Avatar
    Join Date
    Sep 2006
    Location
    Berlin
    Shooter
    Multi Format
    Posts
    355
    OK Bill, of course I have no calibrated sensitometer. I test under my enlarger. You know like it is explained by BTZS. I hope some thing are becoming clear now. BTZS uses the ISO triangle and I always wondered why I was getting more speed than by using the ZS method. Also having problems with flare. Which Stephen explained nicely.
    I think I am slowely starting to see the light. Dimly but it is there.
    Concerning the Delta-X criterion. Wouldn't it be better to use the full length of the curve (Zone VIII) and mathematically calculate the values we would have at using the ISO triangle.

  2. #82
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,346
    Images
    46
    Quote Originally Posted by AndreasT View Post
    Just checking the last graph, the flare also comprsses the contrast of the shadows resulting in worse seperation. By decreasing exposure and expanding development we would improve this.
    You would be better to try to reduce flare. There is reduced separation in the shadows. Fortunately, the reduced separation in shadows is not important to most viewers.

    I recently did some graphs where the tests included flare and they didn't fall below 0.1 density.

    So you can't reduce exposure and expand development to compensate for flare.

    But you can reduce exposure "knowing" that flare will bring up the shadows slightly. Going the other way is OK too. Any increased exposure will look like fogged negatives.

    You can decrease the exposure until you feel you are on the toe of the curve. Then you are at the point where you are not making things better.

  3. #83
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,346
    Images
    46
    Quote Originally Posted by AndreasT View Post
    OK Bill, of course I have no calibrated sensitometer. I test under my enlarger. You know like it is explained by BTZS. I hope some thing are becoming clear now. BTZS uses the ISO triangle and I always wondered why I was getting more speed than by using the ZS method. Also having problems with flare. Which Stephen explained nicely.
    I think I am slowely starting to see the light. Dimly but it is there.
    Concerning the Delta-X criterion. Wouldn't it be better to use the full length of the curve (Zone VIII) and mathematically calculate the values we would have at using the ISO triangle.
    What kind of light source do you have on the enlarger?

    I do use the ISO triangle to find my speed. Then I stick with that speed.

  4. #84
    AndreasT's Avatar
    Join Date
    Sep 2006
    Location
    Berlin
    Shooter
    Multi Format
    Posts
    355
    Tungsten, but I use a filter, I think it is a 80c. Would have to check that up. To compensate the colour somewhat.

  5. #85
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,346
    Images
    46
    Quote Originally Posted by AndreasT View Post
    Tungsten, but I use a filter, I think it is a 80c. Would have to check that up. To compensate the colour somewhat.
    That should be fine.

    So you would use the speed you find at the ISO triangle as a benchmark. And if you start to do different developers/compensating developers etc. Then look how the curves compare to find a new EI. Otherwise take that one speed you found in the first place and use it all the time. Delta-X provides the theory that supports the idea that the effective speed doesn't change a lot with changes in development.

  6. #86
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,346
    Images
    46
    I find, or at least I believe I've found, that I get a little less than ISO speed from my film. So a little under box speed might be what I am REALLY getting.

  7. #87
    AndreasT's Avatar
    Join Date
    Sep 2006
    Location
    Berlin
    Shooter
    Multi Format
    Posts
    355
    Yes basically looking up my data I get a little under box speed.

  8. #88
    AndreasT's Avatar
    Join Date
    Sep 2006
    Location
    Berlin
    Shooter
    Multi Format
    Posts
    355
    But it gets a bit complicated when we go over to development we have to compenstae for flare. Now this has been discussed here and there. I also PM with some other members. At the moment I am compensating for flare my using a contrast log value of 1,20 instead of the "normal" 1,05. Now Stephen also wrote about this as always I did not follow.
    I dare to ask what you Bill, or Stephen thing of this approach.

  9. #89
    Bill Burk's Avatar
    Join Date
    Feb 2010
    Shooter
    4x5 Format
    Posts
    3,346
    Images
    46
    I use a chart Stephen provided that gives Contrast Index to develop to... for the paper grade and subject luminance range.

    I start out with 7 stops == N.

    The chart has Flare compensation built-in.

    And I use the EI based on my speed tests that are basically to the ASA/ISO triangle but I feel are not quite box speed.

    I meter using Zone System notation (spot shadow, place on Zone II, or spot skin place on Zone VI etc.)

  10. #90
    AndreasT's Avatar
    Join Date
    Sep 2006
    Location
    Berlin
    Shooter
    Multi Format
    Posts
    355
    I will check up on those charts again tomorrow. I myself use an incident light meter.

Page 9 of 11 FirstFirst ... 34567891011 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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