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Thread: Determining film speed.

  1. #1

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    Determining film speed.

    Hello.

    I am about to receive my new developing chemicals. I opted for the Ilford DD-X. I soon realised this is a quite expensive developer. So I will be changing to Ilford HC. I need to do some film testing to figure out which ISO/ASA/EI to place my Ilford Delta 100 at and the correct development time. I recently also purchased a 8x10 camera. I have a 4x5 camera. What I am wondering is if it is possible to use the same speed rating and development time for 8x10 film as for 4x5? Determining speed and development for 8x10 with 8x10 sheets will be immensely expensive, seeing I need a lot of sheets if I am to follow what "The Negative" preaches.


    -Fredrick.

  2. #2

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    Re: Determining film speed.

    Quote Originally Posted by Fredrick View Post
    Hello.

    I am about to receive my new developing chemicals. I opted for the Ilford DD-X. I soon realised this is a quite expensive developer. So I will be changing to Ilford HC. I need to do some film testing to figure out which ISO/ASA/EI to place my Ilford Delta 100 at and the correct development time. I recently also purchased a 8x10 camera. I have a 4x5 camera. What I am wondering is if it is possible to use the same speed rating and development time for 8x10 film as for 4x5? Determining speed and development for 8x10 with 8x10 sheets will be immensely expensive, seeing I need a lot of sheets if I am to follow what "The Negative" preaches.


    -Fredrick.
    Of course, as long as you are using the same emulsion.
    One man's Mede is another man's Persian.

  3. #3

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    Re: Determining film speed.

    Quote Originally Posted by E. von Hoegh View Post
    Of course, as long as you are using the same emulsion.
    Yes, I will keep to one emulsion and one developer for the first year. Then I will be certain that I have controll over that process.

    -Fredrick.

  4. #4

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    Re: Determining film speed.

    Depending how you process your sheets of 4x5 vs 8x10 (you could always cut your 8x10 film into quarter sheets then you will be using the same batch!). The procedures you follow may change your needed development time.

    For specific example: I develop anywhere from 6 to 10 sheets of 4x5 film in a tray, shuffling continuously. I find the extent of development varies with the number of sheets. Film developed individually gets processed "faster" because it always has access to fresh developer while stacks of film only get a fresh dose of developer once a minute.

    If you develop 8x10 one sheet at a time, but you develop tests 6 sheets at a time shuffling, (or vice versa) then there will be a difference.

    If you develop test and live film similarly, E. von Hoegh gave spot-on advice. My clarification applies if the process differs significantly.

    Another specific example: I never use tank times for tray processing. They just do not compare.

  5. #5

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    Re: Determining film speed.

    Quote Originally Posted by Bill Burk View Post
    Depending how you process your sheets of 4x5 vs 8x10 (you could always cut your 8x10 film into quarter sheets then you will be using the same batch!). The procedures you follow may change your needed development time.

    For specific example: I develop anywhere from 6 to 10 sheets of 4x5 film in a tray, shuffling continuously. I find the extent of development varies with the number of sheets. Film developed individually gets processed "faster" because it always has access to fresh developer while stacks of film only get a fresh dose of developer once a minute.

    If you develop 8x10 one sheet at a time, but you develop tests 6 sheets at a time shuffling, (or vice versa) then there will be a difference.

    If you develop test and live film similarly, E. von Hoegh gave spot-on advice. My clarification applies if the process differs significantly.

    Another specific example: I never use tank times for tray processing. They just do not compare.
    I think I will keep to processing only 1 sheet at the time for 8x10, that way I can see if it needs less or more development time. I'm a bit of a perfectionist. I have the mod54 for 4x5, and will be using it for developing 4x5. If I find it to be a bad development method, I will just switch to trays.

    I am however going to use a tray and 4x5 film to determine the development time for 8x10. It's more economically sound. Development in a tray will also need less chemicals than development in a tank, right? I know there is some sort of minimum developer per sheet of film, but I don't know what it is.

  6. #6

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    Re: Determining film speed.

    You can determine the minimum amount of developer per sheet by extrapolation from the developer capacity listed on the datasheet for that developer. I.e., x rolls of 35mm film for x qty of developer at x concentration. I believe one sheet of 8x10 = 1 roll of 35mm, or 4 sheets of 4x5...

    A shortcut, or starting point, might be to spend some time on Phil Davis' Beyond the Zone System site, where - if I remember correctly - he uses ~25ml per 4x5 sheet and ~75ml (or is it 125ml?) per 8x10 sheet in BTZS tubes. If you're tray developing though, you will have a hard time processing a sheet of 8x10 film, even if you use an 8x10 tray instead of recommended 11x14 tray, with only 75 (or 125) mls of developer in it!

    Once you get through your testing phase, I doubt you'll stay satisfied for long, processing one sheet at a time. I think you'll find that, once you get your "anti-scratch" shuffle technique down (and you will) you can just as easily do 4-6 sheets of 8x10, or maybe even more. I usually use between 750-1000ml of developer in the tray using either XTOL or Pyrocat HD with HP5 and I've found that it can be hard to keep the film adequately inundated with the developer using much less than that.

  7. #7

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    Re: Determining film speed.

    Quote Originally Posted by Fredrick View Post
    I think I will keep to processing only 1 sheet at the time for 8x10, that way I can see if it needs less or more development time. I'm a bit of a perfectionist. I have the mod54 for 4x5, and will be using it for developing 4x5. If I find it to be a bad development method, I will just switch to trays.

    I am however going to use a tray and 4x5 film to determine the development time for 8x10. It's more economically sound. Development in a tray will also need less chemicals than development in a tank, right? I know there is some sort of minimum developer per sheet of film, but I don't know what it is.
    That's how I do it. Edward Weston did it that way, too. Consistency is more important than method here.
    One man's Mede is another man's Persian.

  8. #8

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    Re: Determining film speed.

    Quote Originally Posted by Fredrick View Post
    Yes, I will keep to one emulsion and one developer for the first year. Then I will be certain that I have controll over that process.

    -Fredrick.
    That's an excellent plan. When I first started using 8x10 I stuck with one lens, one film, and one developer.
    One man's Mede is another man's Persian.

  9. #9

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    Re: Determining film speed.

    Quote Originally Posted by Cletus View Post
    You can determine the minimum amount of developer per sheet by extrapolation from the developer capacity listed on the datasheet for that developer. I.e., x rolls of 35mm film for x qty of developer at x concentration. I believe one sheet of 8x10 = 1 roll of 35mm, or 4 sheets of 4x5...

    A shortcut, or starting point, might be to spend some time on Phil Davis' Beyond the Zone System site, where - if I remember correctly - he uses ~25ml per 4x5 sheet and ~75ml (or is it 125ml?) per 8x10 sheet in BTZS tubes. If you're tray developing though, you will have a hard time processing a sheet of 8x10 film, even if you use an 8x10 tray instead of recommended 11x14 tray, with only 75 (or 125) mls of developer in it!

    Once you get through your testing phase, I doubt you'll stay satisfied for long, processing one sheet at a time. I think you'll find that, once you get your "anti-scratch" shuffle technique down (and you will) you can just as easily do 4-6 sheets of 8x10, or maybe even more. I usually use between 750-1000ml of developer in the tray using either XTOL or Pyrocat HD with HP5 and I've found that it can be hard to keep the film adequately inundated with the developer using much less than that.
    Those BTZS tubes looks very interesting though. Only eight ounces of developer per tubes. That's really not much. Just watched Fred Newman's videos... I get a little scared by the fact that the stop bath is done in full light! I would have to that in the dark... Just for my own sake.
    I'll stick with trays for now, but those tubes sure look alluring.

    -Fredrick.

  10. #10

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    Re: Determining film speed.

    I use a figure of approximately two ounces of stock D-76 per sheet of 4x5 so that would be about eight ounces of stock D-76 per sheet of 8x10. If you choose 1:1 development times, then that would require 16 ounces of developer, which won't fit in a tube.

    My gut instinct tells me (not scientifically established) that using half the recommended amount would lead to inconsistent results that are hard to troubleshoot. For example I imagine not having enough active developer ingredients might affect high-key work where you do not attain predicted density in the highlights while average scenes would be unaffected because they didn't consume as much chemistry.

    My gut also tells me it would be a 15% kind of problem. I get this feeling because when I used a tray twice, my Contrast Index dropped 15%, and the datasheet suggested 15% additional time for re-use.

    ---

    You do not have to open BTZS tubes in bright light, it is a demonstration that you can do it. After long discussions, I have come to believe it may be OK if you use an acid stop and acid fix. A water stop and alkaline fix should be done in the dark because development can proceed in fixer.

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