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Thread: How To Use Stouffer Step Tablet?

  1. #11

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    Re: How To Use Stouffer Step Tablet?

    Thank you very much for taking the time to explain this. This is incredibly helpful and I appreciate your knowledge.


    Quote Originally Posted by ic-racer View Post
    What is ISO(R)? 
This is a means of comparing different manufacturers’ contrast grades in absolute terms. It is the logarithm of the exposure range required to give a full tonal range, expressed to two significant figures, with the decimal point removed. Typical figures might be Grade 5 = ISO(R) 40 to 45; Grade 4 = ISO(R) 60 to 70; Grade 3 = ISO(R) 80 to 90; Grade 2 = ISO(R) 100 to 110; Grade 1 = ISO(R) 120 to 130; Grade 0 = ISO(R) 140 to 150; Grade 00 = ISO(R) 160 to 180.

    The density wedge will progressively give more and more exposure to determine the maximum density for you. Now, if you read the strips with a reflection densitometer, you don't use the "most dark" and "most light" strips to do the ISO(R) calculation or the ISO speed calculations. Just like with film, the density (speed point) is just a little away from maximum black or white.

    I can't find the ISO paper off hand but the paper speeds are based on work represented in this graph from Loyd, 1942 that shows the useful range (which the ISO(R) contrast is based) is not at the exact black and white points. It is complicated to find those points, thus the recommendation to just skip the "near black" and "Near white" strips on the processed paper.


    Attachment 203951

  2. #12

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    Re: How To Use Stouffer Step Tablet?

    Quote Originally Posted by LFLarry View Post
    Thanks, Doremus, that makes sense.

    I was under the impression if I found an exposure time that produced DMAX on the step wedge that this time was my standard printing time or as Fred Picker used to say the Proper Proof time. Am I misunderstanding this concept? If so, please help me learn so I can improve.
    This depends on the correct and consistent exposure and development of the negative. I am not that perfect, so my print exposure times vary and in any case I am more critically interested in the highlights rather than the shadows. Particularly for Platinum/palladium prints, a step tablet laid beside the field of the first print will help me decide about better exposure and contrast.

  3. #13

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    Re: How To Use Stouffer Step Tablet?

    Yes, that makes sense. I use a Jobo processor and I am very consistent how I meter and my development process, so it seems to work really good for me, at least gets me very close to the base exposure for the print and then a little dodging and burning to fine tune.


    Quote Originally Posted by cowanw View Post
    This depends on the correct and consistent exposure and development of the negative. I am not that perfect, so my print exposure times vary and in any case I am more critically interested in the highlights rather than the shadows. Particularly for Platinum/palladium prints, a step tablet laid beside the field of the first print will help me decide about better exposure and contrast.

  4. #14
    Gary Beasley's Avatar
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    Re: How To Use Stouffer Step Tablet?

    I have a 4x5 enlarger and I like to lay the scale on a glass carrier and project a print on whatever paper Im trying out. Looking at the scale print after I blow dry it I find my highlights and shadow tone I want and read corresponding step under the enlarger with my analyser. I can use that to set the exposure up on prints I make from that paper for the time I used to do the test print.

  5. #15
    ic-racer's Avatar
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    Re: How To Use Stouffer Step Tablet?

    Anyone with a stepwedge should have this PDF document from Kodak "Sensitometry Workbook" I usually recommend people read that PDF rather than any 'zone system' papers. I think zone systems cause more confusion.
    It mostly covers film, there is only a 1/2 page about paper sensitometry on page 15.
    https://www.kodak.com/uploadedfiles/...y_workbook.pdf

  6. #16
    ic-racer's Avatar
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    Re: How To Use Stouffer Step Tablet?

    If you project the step wedge that is a good test to compare enlarging lenses for flare. I have a number of lenses that I have cleaned and the still look a little foggy, this is a good test to see, in terms of Log D, how much or little flare that 'little fog' causes.
    Also, if one is worried about painting the wall behind the enlarger black, gray or white, projecting the step wedge while various colored poster boards are set behind the enlarger can tell if there is any change in contrast (flare) between the different poster boards.

  7. #17

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    Re: How To Use Stouffer Step Tablet?

    Quote Originally Posted by LFLarry View Post
    Thanks, Doremus, that makes sense.

    I was under the impression if I found an exposure time that produced DMAX on the step wedge that this time was my standard printing time or as Fred Picker used to say the Proper Proof time. Am I misunderstanding this concept? If so, please help me learn so I can improve.
    The notion of a Proper Proof didn't originate with Fred Picker, although he did promote it; I learned it from the Minor White books.

    Anyway, the idea of making the proper proof is to find the minimum exposure that gives you "maximum black" from the clear rebate of the film (i.e., film base + fog). This exposure will be slightly different for every film and even varies with different development/developer. It will also be different for every paper you use (and contrast setting).

    So, you see, the proper proof has to do with the density of the clear area of the negatives you are proofing, not anything to do with a step wedge (although you can "proper proof" a step tablet too, if it has a clear stripe ).


    Bear with me and I'll go into a bit of detail:

    The proper proof is independent of proper exposure and development of the negative. In fact, it helps you find these.

    To find the proper proofing time, contact print your negative on a piece of photo paper slightly larger than the film, making sure some area of the paper not covered by the negative receives the same exposures as the negative.

    I use an enlarger to do my proofing. I set up the head at an intermediate height, focus the negative carrier on the baseboard and stop down a couple of stops. The idea is to find the light intensity that enables you to make a good test strip that has the "proper proof" exposure somewhere in the 10-30 second range (shorter is less accurate). You may have to adjust light intensity by changing f-stop or head position to get the right exposure range (i.e., you might have to make a couple of test strips).

    Now, make a test strip in, say, 20% intervals (or whatever intervals you are comfortable with). If you're using VC paper, choose a contrast setting that will be your target (preferred/standard) setting, say grade 2 or 2.5. Develop your test strip in your standard print developer for the standard time.

    Fix, rinse and dry your test strip (if you don't dry it, you'll get different results). Now examine your test strip under what you consider to be ideal display lighting. This is important. If you use too bright a light, you'll get proofing times that are too long; too dim and your times will be too short. The problem is with the perception of "maximum paper black" (Fred Picker's term...). You can see more shades of black in bright light than you can in dim light; what you are really after is a good solid black that will serve as your blackest black in a print, not Dmax. Let's call that maximum black just for simplicity's sake.

    Back to your test strip. The part of the paper not covered by the negative will reach this maximum black well before the area covered by the clear rebate of the film. This uncovered area will be the area you compare the black of the film rebate with. Find the first strip where the two blacks (just almost but not quite) match. Add a second or so to this and you have your "proper proofing time" for that film/developer/paper/contrast/paper developer combination.

    Now you can go about proofing your negatives. If you've chosen your maximum black well, the information from a properly proofed negative will tell you a lot about your exposure and development. Shadows too dark? You're underexposing. Highlights blown out? You're overdeveloping, and vice-versa (for that paper contrast setting).

    I proof negatives in batches, and determine my proofing times before each proofing session. If I have more than one film, I'll find the proper-proofing time for each film each time. I use the proper proof as a control on my exposure and development.

    Watch out, however! It's easy to get off on the wrong track by not choosing the right "maximum black." I learned a whole lot about paper black when I started out calibrating things visually a là Minor White. The initial confusion gave way to a much deeper understanding of how the shoulder on papers acts and helped me refine my ideas of what black in a print should really be. It's all a bit Zen after awhile, but well worth delving into IM-HO. In any case, you may have to try a different proper-proofing time once or twice to find the one that really shows what's in the negative and still gives you a good solid black in the print. If there is a lot of shadow detail in the negative that's not showing up at your proper-proofing time, then you're proofing too long. If your blacks are grey, then you're not proofing long enough. Refine till you get your proof to do it's job; i.e., give you info about your exposure and development (remember, a proof is not a fine print, just an intermediate tool, so you just need to be close).

    Hope this helps,

    Doremus

  8. #18

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    Re: How To Use Stouffer Step Tablet?

    This post by Doremus offers valuable and important advice for any, especially new, darkroom worker. Like him, I went off-course trying to get a "maximum black" -- rather than a good working black -- without understanding the caveats he provides, just as I had decades earlier printed too heavily in my attempt to get "good detail in the highlights."

    I fully respect those whose expertise allows them to chart sensitometric data, and don't doubt they they have a finer degree of control over their exposure and development than I, though I aspire and work hard to have good control of my craft. At the same time, I am also reminded of something said by John Sexton, whose sensitometric and artistic credentials few will contest. If these are not his exact words, they are close: "Some strive to make the best contact sheet. I strive to make the best print."
    Philip Ulanowsky

    Sine scientia ars nihil est. (Without science/knowledge, art is nothing.)
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  9. #19

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    Re: How To Use Stouffer Step Tablet?

    What an awesome story, and experience!

  10. #20

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    Re: How To Use Stouffer Step Tablet?

    I'd like to ask a related question - a search for my precise question turned up no more likely thread than this one. I see online two choices for a 4x5 21-step tablet, one for about $20.00 from Photographer's Formulary and the other going for near $70.00 now, from Stouffer. Can anyone comment on results using the cheaper of those two choices, compared to the more expensive one? Thanks.

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