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Thread: Assessing film speed and development time without a darkroom.

  1. #1

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    Assessing film speed and development time without a darkroom.

    Most of my photography is film based. I don’t have a darkroom or enlarger and ‘digitise ‘ my 35 mm, medium format and 5x4 negatives either by film scanning or photographing negatives with a macro lens on a digital camera, then processing these digital files via Lightroom and Photoshop.
    I am keen to arrive at an optimum film speed and development time for any particular combination of film and developing agent.
    I don’t have a densitometer.
    Is there any technique available to me to achieve my objective in the absence of darkroom facilities?

  2. #2
    Drew Wiley
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    Re: Assessing film speed and development time without a darkroom.

    Find someone else who can do the processing and take the readings for you, as well as explain how to take relevant test shots with a good gray scale or gray card target. If you shoot roll film, you could use a light-tight film tent or dark closet to load the film into a hand-inversion processing drum, alleviating the need for a complete darkroom. But without prior darkroom experience or taking a class, that might prove clumsy at first.

  3. #3

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    Re: Assessing film speed and development time without a darkroom.

    A really useful way to start is by following the film data sheet recommendations and that film manufacturer’s processing recommendations. The major film companies have plenty of free documents to download on how-to.

    As someone already said, there are daylight tanks for both roll and sheet film and you can do all of the dark work in a big changing bag. Not ideal but it can be done.

  4. #4

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    Re: Assessing film speed and development time without a darkroom.

    Quote Originally Posted by BrianShaw View Post
    A really useful way to start is by following the film data sheet recommendations and that film manufacturer’s processing recommendations. The major film companies have plenty of free documents to download on how-to.

    As someone already said, there are daylight tanks for both roll and sheet film and you can do all of the dark work in a big changing bag. Not ideal but it can be done.
    I process my own B&W negatives using Patterson or Stearman tanks. I have used manufacturers or Massive dev charts to arrive at development times but have no objective way of assessing Zone 1 and Zone 9 densities. This is usually achieved by running test strips on paper at incremental increases of exposure, but no enlarger, timer or darkroom means this is not an option for me.

  5. #5

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    Re: Assessing film speed and development time without a darkroom.

    Using a known-density reference (e.g. a stouffer wedge) you can use your scanner as a densitometer. Scan the reference along with the film in one go and 'measure' densities in Photoshop etc.

  6. #6

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    Re: Assessing film speed and development time without a darkroom.

    Or, you can just adjust on the fly, optimizing your negatives for your digital printing method using the time-honored advice:

    If your shadows don't have enough detail, rate the film slower.
    If your negatives are too contrasty to print well, develop for a shorter time, and vice-versa.

    What you are looking for is the minimum exposure that will give you the shadow detail you need and the minimum developing time that will give you the print you want at "average" or "normal" settings (whatever those might be for your method).

    Now, if you want your negatives to be printable in the darkroom, then you'd have to take this into account by making sure you expose and develop enough for conventional printing. Still, the same parameters apply, it's just that it's the photographic paper that will tell the tale instead of your digital scan or copy shot.

    For that, you'll need somehow to measure densities and contrast gradient, or get someone to print your negatives conventionally and see how they print at a medium contrast setting. If you don't anticipate ever needing to print conventionally, then optimizing for your workflow is just fine.

    Best,

    Doremus

  7. #7
    Drew Wiley
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    Re: Assessing film speed and development time without a darkroom.

    There's also the old do-it-yourself "visual densitometry method". Take some black card stock and punch two holes in it several inches apart. Put your film on a light box along with an adjacent calibrated Stouffer step wedge, each adjusted below its own respective hole at the point you want to compare them. Each step of the wedge is about .15 density apart. With your eyesight alone, you should be able to discern density differences within .05, plenty good for most black and white film purposes.

  8. #8

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    Re: Assessing film speed and development time without a darkroom.

    Thanks everyone for all the input.
    I like the Stouffer step wedge approach. So for clarification; if I expose a 35 mm or 120 roll film at a series of exposures of a plain evenly lit surface, making a note of the Zone values I think they represent at a given film speed, and then compare these with a Stouffer step wedge by the naked eye alongside my film, I should be able to discern how close to actuality I am with Zone 1, and then adjust film speed accordingly? And would the same approach work for determining the optimum developing time by matching Zone 9?
    Thanks

  9. #9
    Drew Wiley
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    Re: Assessing film speed and development time without a darkroom.

    It's a valid start. With most films and developers, you want the darkest evident shadow texture or differentiation (Zone II) to correspond to around .15 density on the step wedge. But there are somewhat different opinions on this depending on the actual application of the film afterwards, since you see to be planning on scanning. The point is, a little extra exposure to the shadows is better than too little. Then the amount of development controls the density of the highlights. You will need to experiment a bit with scanning and printing to iron out everything to your own taste. It helps to standardize on just one film and developer when starting out. But some of the ancient common sense advice about how much development is too much still applies : After development, if your negative is too dense to read or discern the text of a book through, it's probably unprintable in those areas with respect to top highlight texture (around Zone IX).

    It might be wise to aim for a VERSATILE density range in your negatives. I have noticed that those who in the past made excellent darkroom enlargements from their negatives, and then later began digital black and white printing, found those same negatives to be especially cooperative for scanning because the density range was sensible. Or it could work the other way around, and someone who begins with digital evaluation later acquires a yen for darkroom printing.
    Last edited by Drew Wiley; 7-Aug-2022 at 09:36.

  10. #10

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    Re: Assessing film speed and development time without a darkroom.

    Quote Originally Posted by JohnF View Post
    Most of my photography is film based. I don’t have a darkroom or enlarger and ‘digitise ‘ my 35 mm, medium format and 5x4 negatives either by film scanning or photographing negatives with a macro lens on a digital camera, then processing these digital files via Lightroom and Photoshop.
    I am keen to arrive at an optimum film speed and development time for any particular combination of film and developing agent.
    I don’t have a densitometer.
    Is there any technique available to me to achieve my objective in the absence of darkroom facilities?
    You have got a densitometer: the spot metering funktion in your camera.

    All you have to do is developing your negatives and metering them out.

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