Stouffer Step Exposure

Discussion in 'Large Format Cameras and Accessories' started by Shaggysk8, Jan 10, 2011.

  1. Shaggysk8

    Shaggysk8 Member

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    Ok I have looked and keep getting confused, I will be getting my first 4x5 soon and I have read you can use a Stouffer Step and take a picture then develop and work out density.

    So my question is, I have a 21 Step can I use this and how do I take a picture of it, how do i expose on it. The may sound like a silly question but I have read so much I have just confused myself.

    A nice step by step with bullet points would be handy :D

    Paul
     
  2. holmburgers

    holmburgers Member

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    I'm not sure exactly what you need to know, as you haven't stated your intention. "Work out density", what specifically are you trying to find out?

    You'll have to backlight it and then meter whatever step you want to be middle gray. This might be a chore with a small step wedge, and hopefully you have a spot meter. Surely someone with a better answer will chirp soon.
     
  3. David William White

    David William White Member

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    It's a printing aid. You set the step wedge beside your negative when making your contact print. You need a contact exposure long enough to render all the steps faithfully in the wedge. That gives you the best contact time. In that sense, the step wedge is an ideal negative.

    If, when you arrive at a contact print that faithfully reproduces the steps but does not give you a nice looking contact print of your negative, then it indicates you are over or under exposed, or over or under developed.

    By varying your contact time, you can work out how to modify your exposure and/or development.


    There are other uses, like verifying the tonal range of an unmarked batch of paper, verifying your chemistry isn't exhausted, working out tonal transfer functions for alt process, but that is the nutshell.
     
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  4. ic-racer

    ic-racer Member

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    It might take months to wade through the varoius threads here on what do do (we need a film testing FAQ).

    The two questions are:
    1) How much exposure does the film need for excellent prints?
    2) How long to develop the film to print on your favorite printing materials?


    To answer #1 above, I like the simple zone I test where you just shoot a uniform target at zone I and check that the negative density is 0.1 (1/3 stop) above film base.

    To determine how long the develop the film, you need to have already estabilshed that by printing and trial and error. Once you know your favorite gamma or contrst index, you can expose the wedge by taping it on unknown film and exposing it to get density data from which the H&D curve can be produced. Then by trial and error you can process the film to match the gamma or contrast index you previously found to be good with other films.

    This is just one way to do it (the way I'd suggest in a FAQ), but there are many, many ways to answer the two questions above, perhaps some even better than what I have suggested. (Or buy Ralph's book, its all in there :wink: )
     
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  5. RalphLambrecht

    RalphLambrecht Subscriber

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    Paul

    Let's start with your list.

    1. What is your goal? (film test, paper test, both)
    2. Do you have a spotmeter?
    3. Do you have a densitometer?
    4. Why did you pick a 21-step for a 4x5 and not a 31-step?
    5. Are you familiar with film, paper testing?
    6. Do you understand log densities and how they relate to exposure?

    Answering these questions will make it a lot easier to give you appropriate answers.
     
  6. michaelbsc

    michaelbsc Member

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    I agree, but I would say FAQs plural.

    Other wise it would become like the developer wars. (Huh?! NO! I did *NOT* say Rodinal.)
     
  7. Shaggysk8

    Shaggysk8 Member

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    1. What is your goal? (film test, paper test, both)
    To start with film test, I want to get the densitys correct

    2. Do you have a spotmeter?
    Yes I do, two in fact but I can only use one at a time

    3. Do you have a densitometer?
    In the post (melico photo log TD2)

    4. Why did you pick a 21-step for a 4x5 and not a 31-step?
    I use to make plates for a litho press after designing and I seemed to acquire it

    5. Are you familiar with film, paper testing?
    Yeah sort of, done a bit and have your amazing book (2nd) I think I am just a little confused

    6. Do you understand log densities and how they relate to exposure?
    Sort of but not really I get the whole thing but then I don't.

    I really want to be able to predict what I am taking the best I can so I can control the whole process better.

    I am a designer that designs for flexo presses (not the most accurate presses in the would) and I can predict the out come for that, and in many areas it is very much the same, but I just feel I need some do that do this advice and then I can go from there. So many people have there way of doing things and when you read it all you end up with a dense neg and black print...hahaha

    All my roll film has come out ok, but this move into large format I want to create and paint an image rather than take one.

    Paul
     
  8. RalphLambrecht

    RalphLambrecht Subscriber

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    Paul

    This should work. To start with, set your spotmeter to the advertised film speed (ISO rating), tape your step wedge to a north-facing window, and measure step 11 (I assume you have a TP 4x5 step wedge). You can get as close as you like and your spotmeter allows you to. This will give you your exposure.

    This and the rest is in the book, starting on page 217 with 'Elaborate and Precise' by the way. Step-by-step instructions are on page 221.

    Once your ready and still have a question, let me know.
     
  9. Martin Aislabie

    Martin Aislabie Subscriber

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    Paul, if you want to do some film testing buy Ralphs excellent book - Way Beyond the Monochrome

    Its now in its 2nd edition

    It explains how to do your own film testing and provides the charts for you to plot out your results

    Alternatively, if you want someone else to do all the hard work for you - buy the book Beyond the Zone System by Phil Davis and a film test from Fred Newman at the View Camera Store

    Martin
     
  10. CPorter

    CPorter Member

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    Just another source here for learning how to test film using a step tablet. The 4x5 step tablet is loaded in the film holder on top of the film and exposed.
     

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  11. John Kasaian

    John Kasaian Member

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    I just use an old Kodak exposure guide. I think Delta makes them nowadays.
     
  12. RalphLambrecht

    RalphLambrecht Subscriber

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    Always good to compare methods, but there are reports about some film holders not able to take film and step tablet (too thick). Also, the OP has one of the following step wedges, and I don't know if they fit into the film holder.

    http://www.stouffer.net/TransPage.htm

    Anyway, I think it may be more realistic to actually photograph the tablet. This way you get the 'real' workflow with meter and camera flare and the difference between meter and the actual exposure, which is a mixture of image-forming and non-image-forming light.

    A further method is to do it all in the darkroom, using the enlarger. After fitting a large-format lens to the enlarger, this works well, but it has the same advantage or disadvantage as placing the tablet into the film holder.
     
  13. Lee L

    Lee L Member

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    I use a Stouffer 4x5 inch 31 step transmission wedge in the following way.

    First, I place the wedge in a negative carrier and backlight it with evenly diffused light, with all stray light around it blocked off to prevent excessive flare. Then I photograph the step wedge with the film and camera I'm testing, using only the central portion of the negative, regardless of format. Since the Stouffer wedges are 10 stops, I meter the backlight without the wedge in place, and then set the exposure at 5 stops greater exposure than the backlight. This places the middle step(s) of the Stouffer wedge at medium gray, or what a Zone System user would call Zone V. It also gives a scale that reaches +/- 5 stops from middle gray, enough to cover 99% of shooting situations. I bracket if I feel I need more than the 10 stop range to test for unknown film speed or other factors.

    I develop the film and then place it in the enlarger I use for printing. I project the negative of the step wedge onto the baseboard and focus, then read the steps with a Darkroom Automation Enlarging Meter. This gives me relative readings in stops (to 0.01 stop resolution) for each wedge, which is easily converted in a spreadsheet to optical density by multiplying by 0.30. The reason I use only the central 1/3 or so of the negative is to minimize light falloff in the enlarger. With the spreadsheet it's very easy to calculate fb+f and find where the Zone I density falls. The spreadsheet can draw a graph and calculate your choice of contrast indicators.

    As Ralph indicates, this is a real end-to-end test of the process. It's also a very quick and easy way to add a one frame process control strip to any single sheet or single frame of roll film.

    Lee
     
  14. CPorter

    CPorter Member

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    I have a Stouffer 4x5 21 step tablet and the film and the tablet fits my Fidelity Deluxe holders just fine--those are the only holders I have so I can't speak for any other holders.

    I understand fully there is a difference of opinion in how the wedge should be exposed. I can only say that I have enjoyed very fine negatives with this testing procedure and I can't honestly say the arguments I have seen (we have seen in other threads) are compelling enough to redo my tests. My negatives I'm producing just do not indicate a need for change.

    Thanks for your input though, always appreciated.