How To Use Stouffer Step Tablet?

[LFLarry]

I just ordered my first 21 step Stouffer's step tablet and I want to make sure I understand how to use it properly when testing papers for the total exposure/brightness range?

What is the proper way to find the right expsosure to use when testing papers?


Thank you for your help.

[ic-racer]

Contact it to the paper tightly so no light leaks around. If light leaks around the dense strips this will mess up readings. If you just want to measure contrast, expose so the entire scale fits in the step tab. If you want to compare paper speeds, you need to do some trial to get the correct exposure time so your speed point shows up in all the tests without altering the time.

Cheap and dirty way to determine the conrast. Count the strips between the darkest and lightest. Multiply by 15 to get ISO(R).

So if 5 gray strips are present, 5 x 15 = ISO(R) = 75 = about 3.5 grade.

[ic-racer]

How not to do it. This one was not held down tight and light leaked around the edge. This one is from taking the color head and setting right on the paper with the step wedge between. The wedge really needs to be held flat. With collimated light (When projecting light from a lens), this bleed is less likely to occur.

203947

[LFLarry]

Very helpful, thank you.

How do I first determine the correct exposure to use to expose the tablet for my paper/developer combination?

I assume if I do exposure tests in small increments on the paper alone, that will get me close to the proper time to use. Normally I would use an unexposed but developed sheet of film to lay over the paper when doing the small incremental exposures, but the step tablet doesn't have that blank area I think? I just want to make sure I am doing this correctly...

Thank you.






Contact it to the paper tightly so no light leaks around. If light leaks around the dense strips this will mess up readings. If you just want to measure contrast, expose so the entire scale fits in the step tab. If you want to compare paper speeds, you need to do some trial to get the correct exposure time so your speed point shows up in all the tests without altering the time.

Cheap and dirty way to determine the conrast. Count the strips between the darkest and lightest. Multiply by 15 to get ISO(R).

So if 5 gray strips are present, 5 x 15 = ISO(R) = 75 = about 3.5 grade.

[Greg]

Brings back a memory when I was a student at RIT in the mid 1970s. Went something like this: I was taking a Materials and Process course under Hollis Todd. About midway through the semester, Hollis Todd said in class that the contrast of a paper did not change with the developing times, only the reflection densities got higher. I stopped by his office and told him that I begged to differ with this teaching (published in his book Photographic Sensitometry). He looked at me and told me to prove it. Spent the next week or two conducting test. Using one enlarging paper (most probably Varigam or Varilour), with a step wedge to calculate the paper's contrasts for different developing times. My readings indicated that the contrast did change with increased development times. Wrote it all up and quite nervously presented my findings to him. He sat back in his office chair and read my findings. Then said something like "you know what this means.... you just earned an A for the course." He told me that when he and written his book (probably 6+ years earlier) his teaching was correct for graded papers, but it was not correct for the VC paper that I was using. From then on I would stop by his office every week to engage in a great academic discussion. Still have one of the test strips that I made back then (attached).

[Pere Casals]

He told me that when he and written his book (probably 6+ years earlier) his teaching was correct for graded papers, but it was not correct for the VC paper that I was using.

Interesting...

[Doremus Scudder]

FWIW, my tests with different papers and developing times have all shown that extra development basically increases paper speed, but not contrast. I imagine different papers react differently.

To the OP:

Your exposure for the step tablet just has to be enough that you have both max. black and white somewhere on the scale. You use the step tablet to see how contrasty your paper is or to keep tabs on process (developer exhaustion). You don't use it to determine a print exposure for actual printing.

Best,

Doremus

[Pere Casals]

FWIW, my tests with different papers and developing times have all shown that extra development basically increases paper speed, but not contrast. I imagine different papers react differently.


Doremus, just an speculation, perhaps (to be checked) this may depend on developer and of base grade. Supose that we expose basicly the green sensitive component of the emulsion, if development is more energic perhaps more infective development may take place from crystals of the blue-only sensitive component... (in fact there are 3 components or more in the VC paper)

After developing to completion further infective development may take place, perhaps... Again, this is only a reasoning...

[LFLarry]

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.



FWIW, my tests with different papers and developing times have all shown that extra development basically increases paper speed, but not contrast. I imagine different papers react differently.

To the OP:

Your exposure for the step tablet just has to be enough that you have both max. black and white somewhere on the scale. You use the step tablet to see how contrasty your paper is or to keep tabs on process (developer exhaustion). You don't use it to determine a print exposure for actual printing.

Best,

Doremus

[ic-racer]

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.


203951

[LFLarry]

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



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.


203951

[cowanw]

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.

[LFLarry]

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.



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.

[Gary Beasley]

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.

[ic-racer]

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/motion/US_plugins_acrobat_en_motion_education_sensitometry_workbook.pdf

[ic-racer]

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.

[Doremus Scudder]

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

[Ulophot]

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."

[earlnash]

What an awesome story, and experience!

[tomwilliams]

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.

[tomwilliams]

My mistake on that Photographer's Formulary price - the $20 was for a 35mm sized tablet.

[Kiwi7475]

If you can, get the 31-step which gives you 1/3 stops. May be overkill now but you may find it useful.
In fact if you overexpose it (so that there’s more than one max black step on your print), you can get the precise time just by counting how many are indistinguishable, so in one step you can get both max black and the min exposure time for it (the 1/3 step helps nailing it with more precision). Basically decrease the time that you used to expose it by the number of stops before the last max black (e.g. if there’s 4 indistinguishable blacks and the strip is in steps of 1/3 of stop, then basically reducing it by 3 x 1/3 = 1 stop or half the time will move the max black to the top and it would be the only max black in the next test with a strip). That’s accurate to +/-1/2 the step size in the strip. Obviously you need to get at least 2 max blacks for it to work. But you can start really long in time since you have 10 stops to play with in the strip.

[tomwilliams]

Thanks Kiwi. I popped for the 21-step tablet a bit before reading your post.

[brittonie]

Brings back a memory when I was a student at RIT in the mid 1970s. Went something like this: I was taking a Materials and Process course under Hollis Todd. About midway through the semester, Hollis Todd said in class that the contrast of a paper did not change with the developing times, only the reflection densities got higher. I stopped by his office and told him that I begged to differ with this teaching (published in his book Photographic Sensitometry). He looked at me and told me to prove it. Spent the next week or two conducting test. Using one enlarging paper (most probably Varigam or Varilour), with a step wedge to calculate the paper's contrasts for different developing times. My readings indicated that the contrast did change with increased development times. Wrote it all up and quite nervously presented my findings to him. He sat back in his office chair and read my findings. Then said something like "you know what this means.... you just earned an A for the course." He told me that when he and written his book (probably 6+ years earlier) his teaching was correct for graded papers, but it was not correct for the VC paper that I was using. From then on I would stop by his office every week to engage in a great academic discussion. Still have one of the test strips that I made back then (attached).

Reading this story just made me so warm and fuzzy 💜

[Serge S]

Great story, goes to prove, it's good to check for yourself:)


Brings back a memory when I was a student at RIT in the mid 1970s. Went something like this: I was taking a Materials and Process course under Hollis Todd. About midway through the semester, Hollis Todd said in class that the contrast of a paper did not change with the developing times, only the reflection densities got higher. I stopped by his office and told him that I begged to differ with this teaching (published in his book Photographic Sensitometry). He looked at me and told me to prove it. Spent the next week or two conducting test. Using one enlarging paper (most probably Varigam or Varilour), with a step wedge to calculate the paper's contrasts for different developing times. My readings indicated that the contrast did change with increased development times. Wrote it all up and quite nervously presented my findings to him. He sat back in his office chair and read my findings. Then said something like "you know what this means.... you just earned an A for the course." He told me that when he and written his book (probably 6+ years earlier) his teaching was correct for graded papers, but it was not correct for the VC paper that I was using. From then on I would stop by his office every week to engage in a great academic discussion. Still have one of the test strips that I made back then (attached).

[Drew Wiley]

First of all, are you using the step wedge via contact or via projection in an enlarger carrier. You need to match it to your technique, whether contact printing or enlarging. If the latter, your results will be erroneous unless your light is totally even when it reaches the step tablet. I prefer the kind of Stouffer tablet on a piece of 4X5 with the strip cut in half, side by side, rather than having all 21 steps in linear configuration. It's also important that the color of the fbf on the step tablet approximate that or your own negatives. Some of the old used tablets are terribly yellowed. The new ones are quite neutral, but that might work against you if you are trying to calibrate pyro stained negatives.