Working idea - Zone System exposure - Time/CI darkroom

[Bill Burk]

I've been working up a system with the help of Stephen Benskin and other APUG members as we go along...

It's close enough to working to discuss...

My idea is that different sides of the brain are involved in different aspects of photography.

In the field taking pictures and in the darkroom making prints - creativity is important.

In the lab testing and developing film, deciding film speed - analytical process is important.
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So I picked pieces from different concepts and chose processes that I like according to how well they work with how my brain works at different times.


Taking pictures, I use traditional Zone System nomenclature. I spot a shadow and place on Zone II. I spot caucasian flesh and place on Zone VI. I can spot highlights and place on Zone VII. All the placing and N developing nomenclature is available and usable pretty much as is.
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Then I go to the darkroom. Here it's sensitometry all the way. Film tests are run and graphed. Time/CI chart is devised. Control is established so that I can hit any CI that I desire (or at least know when I'm out of control). I also can know the effective EI from the graphs.
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EI - the variable I change to place my exposures where I want them on the film curve. I originally started arbitrarily at half box speed (primarily to give shadows full exposure), but I found results consistently denser than necessary - I now use one-third stop up from half box speed.
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Film developing. Knowing my Subject Brightness range - after all I did mark each sheet N, N+1, N-1 or made notes about the overall conditions for the roll.

I target either 1.05 or 0.95 Log Exposure Range (LER) because my specification for a quality negative is to never have a worse negative than two real negatives of mine. They were difficult but successful prints. I call them my upper control limit 1.18 and lower control limit 0.86. You must choose your own specification for a quality negative of your own. Because I use Galerie 2 and Galerie 3 on a DII with Omegalite that's where I came out with my own aim point.

In the Zone Placement thread...

(there was a url link here which no longer exists)

Stephen Benskin provides a chart that tells what CI to develop to in order to get a desired LER

(there was a url link here which no longer exists)

So I develop according to my Time/Contrast Index chart (derived from family of sensitometry).
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Then it comes to the darkroom for printing. Creative mind takes over the high-tech analytical side shuts down...

Now I have negatives that are likely to fit Grade 2 or Grade 3 paper. That's all I have. So I make a call. Is the neg kind of thin or kind of contrasty. Not a tough call. I pick Grade 2, make a test strip by F/Stop times in third-stop increments. Take a look at the result, try to estimate dry-down (I use Fiber Based paper). I sketch out my burns and dodges.

This is where having a negative that prints well on Grade 2 is a pleasure. The burns and dodges have the effect I was going for. Usually I will see "something" wrong and have to print again for an improvement. Like Bob Carnie, I make 3 prints. Like ROL, sometimes I make a noticeable improvement each time.

 

[chriscrawfordphoto]

The only problem I see is that EI is related to developer. You can't really say "I'll shoot at half box speed, or 1/3 stop from box speed or whatever." The same film may need totally different EI in different developers. For example, I shoot Tri-X at 320 for normal developing in D-76 1+1, 250 in Rodinal 1+50, and 200 in PMK. These speeds give the same shadow density for negs developed to the same contrast in each developer.

 

[Stephen Benskin]

Bill,

It all sounds good to me.

I have a feeling you are using a general purpose developer in a one shot capacity which tends to produce speeds comparable to the ISO speeds. Field testing should be sufficient. Besides, as I've pointed out many times, the accuracy of most people's speed testing is highly questionable.

 

[paul ron]

When speed testing film, it's a personal rating. Your shutter may not be functioning perfectly, your meter is not the same as even they varry brand to brand as well as type. Your interpretation of a shadow in ZIII vs a highlight in ZVIII is subjective n open to personal interpretation.

By testing you are compensating for all these personal variables. The science n technique just has to be good. You should have posted "results may varry."

Nice work, you've got me.

.

 

[Stephen Benskin]

By testing you are compensating for all these personal variables.

I believe this is an urban legend. Does anyone test every lens, at every shutter speed, at every f/stop? There are a bunch of other variables that aren't even considered most of the time? If a person is concerned about the meter calibration. Get it checked. Same goes for the lens and lens or camera shutter. Then if necessary factor it in.

Your interpretation of a shadow in ZIII vs a highlight in ZVIII is subjective n open to personal interpretation.

I agree that metering preferences have the greatest influence on exposure and that can be determined in the field.

 

[Bill Burk]

The only problem I see is that EI is related to developer.

My film developing lab, is in the "left-brain" system. I test by exposing 5 sheets of film sensitometrically and developing to varying minutes, graphing and plotting the Contrast Index. (Same test Fred Newman can provide as a service).

Stephen you are correct, I am using D-76 1:1 one-shot and obtain rated speed where the graph fits the ASA triangle.

So Chris, If you use a different developer, then the "obtained" speed on the graph could change. I would take the "obtained speed" as the "box speed" and make my arbitrary adjustment to EI from that.

 

[Bill Burk]

When speed testing film, it's a personal rating. Your shutter may not be functioning perfectly, your meter is not the same as even they varry brand to brand as well as type.

Thanks paul ron,

Boy do I know it. My wife keeps asking me if I haven't memorized the little yellow Minor White book. My painted plywood two-tone target still reads one stop different tone-to-tone by my analog Pentax V - but the digital Sekonic says it's a lousy target.

So I depart from tradition when it comes to testing. I use a sensitometer and densitometer and graph the results on paper. The camera tests took an hour or more to setup and shoot (great for learning but very difficult to maintain in practice - for over a year I shot TMAX-400 at 64 because of vignetting in my test setup) - with a sensitometer it only takes a moment to expose a test strip.

My arbitrary change to EI is where I think the personal adjustment for camera and lens comes in. Or maybe it is built into the "standard flare model" that the SBR/LER/CI chart is based on.

 

[MaximusM3]

I don't know, guys. I think people make too much of this stuff. People like to dump on Adams these days but really, his zone system basics are all people need to make good negatives, as long as we realize targetting a paper range is not always the best way to a fine print. It only works for scenes of average luminance ranges. Even without precise flare factors etc, the basic testing methods in Adams's book are pretty good, and that was with graded paper. VC papers give us even more flexiblity.

I believe when plotting H&D curves and such, it is wise to test in-camera (as Adams suggests) rather than with sensitometers and/or step tablets. In-camera testing introduces some flare, and shutter speed/aperture errors - the kinds of things we ultimately face in the field. Sensitometers are efficient and precise, but represent "lab conditions".

All this business about CI, BTZS, and log exposure ranges to two decimal places?? I highly doubt anybody can control their processes with such precision. In the field, I'd argue anything much smaller than half a stop amounts to quibbling, and is within the normal margin of error. My educated guess is people who measure their film speeds, SBRs and density ranges for development times etc in 1/3 or 1/4 stop increments are fooling themselves, and wasting time instead of mastering printing controls.

Thoughts?

I think that you are correct on all counts, Michael. These tools are to be used to make a good final print, if one chooses to use them, but they are certainly not to be obsessed over. Close enough, is usually good enough for me in the darkroom. The rest I can fix with VC and other gimmicks, if they need to be fixed at all. A "perfect" negative, whatever that means, certainly doesn't guarantee a winning image/print so why agonize? Frankly, the when it comes to photography, a great negative is the least of my concerns. I'm more interested in finding something worth shooting and printing.

 

[Allen Friday]

"The production of a perfect picture by means of photography is an art. The production of a technically perfect negative is a science." Ferdinand Hurter.

 

[Bob Carnie]

I think you are all right.

When I start any major project or series, like Bill / Stephen I test test test, to figure out the conditions.took me a year to figure out the solarization process I do.
once this testing is done, I then go with Michael's approach and do not worry about the small details.

I have to admit that I do not use a meter, but rely on my eyes , sunny 16 and some basics that get me within the 1/2 stop that Michael mentions.
A good understanding of lighting ratios help in determining your starting point, and I do use the same materials all the time for consistancey.

Once I have a negative in my hand , I can pretty much adjust the final print with the tools available to me in the darkroom.

 

[LCEL]

This thread is good reading.
What recent published books (using modern films and developers) would you recommend?
I have loads of books on this subject but they are all at least 30+ years old.

Best regards,
LCEL.

 

[Chuck_P]

Good thread Bill, I think I progress with the left brain right brain concept much like you do, when I can put paper to the easel, I have a greater feeling of creativity. Following along your train of thought:

1. Taking pictures: traditional ZS nomenclature all the way as well, it's how I learned. I use a Pentax V spot meter, I never place a highlight. Subject and the visualization dictate the lower value placement--I have made a scale of zones on a textured surface based on my TMX film speed test and I always visualize that when deciding on the placement and where other values "fall", placements from ZII, III, IV, dominate my negs, ZII placements suggests a hint of texture in the area intended, but is never meant to be a dominant part of the final print, an exposure placement that low, to me, must always serve Zones III - V or VI quite well.

2. Film Developing: all speed and dev time testing is performed with a step wedge in-camera. I don't develop to any specific CI. The speed point serves as a pivot point for adjustment of the dev time so that the curve hits its target for plus and minus times. In the case of +2 or -2 or -3 development, the toe of the curve shifts, respectively, on the log E scale, thus shifting the effective film speed, in my tests by 1/3 to 1/2 stop either way. However, I keep the tested speed a constant and adjust for this in the field with the exposure when I know these extreme development conditions are planned. Ex: a tested EI of 80 remains 80 for simplicity, if I plan +2 development, I reduce the final exposure by 1/3 to 1/2 stop, since at +2, the toe has moved to the left, indicating less exposure is needed to reach the threshhold.

I have found thus far that my negative density range of about 1.2 serves me well with Ilford MGIV FB; I use contrast filtration with my LPL that provides a LER of about 1.1 or so, which is in the soft 2 to hard 1 contrast grade; not an exact fit, but I've not experienced a reason to adust anything yet, going to work on this more extensively when the darkroom gets finished.

3. Printing: I like the basic test strip method, don't use whole sheets but cut wider strips for economy; I do not split-grade print, I set the global contrast with one filtration setting, then adjust filtration if needed for the burning in pieces. It's dektol most always at 1:2; I try to make good use of the trash can, sometimes it's hard.

 

[Bill Burk]

What recent published books (using modern films and developers) would you recommend?

Way Beyond Monochrome

 

[Bill Burk]

2. Film Developing: all speed and dev time testing is performed with a step wedge in-camera. I don't develop to any specific CI.
...
I have found thus far that my negative density range of about 1.2 serves me well with Ilford MGIV FB.

Hi CPorter,

Since camera step wedge tests are recommended by Ralph Lambrecht, that's good endorsement, others looking for a practical test should consider it. I'll keep using the sensitometer because I have it.

When you develop to about 1.2 you are basically developing to a certain CI (you just don't realize it).

Since I hit a wall at Grade 2, 1.2 is just a bit outside my upper control limit. There are some suggestions that a lower target leads to negatives with better qualities (such as less graininess). Something to consider if that matters to you. I have chosen to allow graininess.

 

[Chuck_P]

Hi CPorter,

Since camera step wedge tests are recommended by Ralph Lambrecht, that's good endorsement, others looking for a practical test should consider it. I'll keep using the sensitometer because I have it.

When you develop to about 1.2 you are basically developing to a certain CI (you just don't realize it).

Since I hit a wall at Grade 2, 1.2 is just a bit outside my upper control limit. There are some suggestions that a lower target leads to negatives with better qualities (such as less graininess). Something to consider if that matters to you. I have chosen to allow graininess.

I thought Ralph did not necessarily endorse the "in-camera" method of exposing the step wedge, I could easily be wrong. I know that others that chime in regularly do not, but I have no ill-experiences with it that I can report.

Let me clarify my statement on CI, I'm aware that a CI can be calculated from any curve; I have out of curiosity calculated it on one of my "normal" curves, but it has no relevance, none whatsoever, in any decision making in my evaluation of the curve.

Regarding the LER, I certainly intend to give that more attention when the darkroom is up and running, but it will need to yield a good difference in a little testing before I feel the need to change anything.

 

[paul ron]

When speed testing film, it's a personal rating. Your shutter may not be functioning perfectly, your meter is not the same as even they varry brand to brand as well as type. Your interpretation of a shadow in ZIII vs a highlight in ZVIII is subjective n open to personal interpretation.

By testing you are compensating for all these personal variables. The science n technique just has to be good. You should have posted "results may varry."

Nice work, you've got me.

.

I'm sorry that maybe should have read differently....

not all shutters are created equally n do have their inconsistancies. Lenses with built in shutters are teh worst offenders as they will varry from lens to lens. I repair RBs n do test my lenses and know exactly how much they are out even though they are still within tolerance I need to see how much they effect my negatives anyway to be sure.

I don't worry about my meters being accurate, I just want em to be consistant. I couldn't care if it compares to the rest of the meters in the world it just has to reproduce the same results each n every time. Even a sunny 16 rule willwork, no meter but at least my tests will reflect my personal judgement in my ratings.

Besides, even if your shutters n meters are not up to par, as long as you did the tests adn you are aware of their inconsistancies, everything else is consistant n reproduceable, eliminate as many of the variables as you can; then even a pin hole camera, stop watch and a photo cell on a VOM will preform better as a result of the testing... these are called personal ratings.

BTW Expensive equipment well maintained accurate n precise still doesn't make better pictures, only a better phoptographer will make a difference. To be a bettter photographer you have to "know" your craft A to Z n that comes from lots of experiance... which is a by product of testing n experimneting, which gives you lots of confidance in your system and makes you a better photogrpher that will perhaps take better pictures.


.

 

[Bill Burk]

Let me clarify my statement on CI, I'm aware that a CI can be calculated from any curve; I have out of curiosity calculated it on one of my "normal" curves, but it has no relevance, none whatsoever, in any decision making in my evaluation of the curve.

Regarding the LER, I certainly intend to give that more attention when the darkroom is up and running, but it will need to yield a good difference in a little testing before I feel the need to change anything.

My comfort with CI may come from the fact I am graphing on paper and use a transparent overlay to determine it. The numbers didn't do me any good until Stephen provided the practical lookup reference. My original plans were to draw horizontal lines on my graph for the paper.
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I want to alert everyone that matching Grade 2 theoretically produces worse negs because it requires developing to a greater degree than the minimum required. It might not matter much but you ought to know.
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Anyone happy printing on Grade 4 is already working hard in the darkroom and quite possibly producing superior results. Don't switch to Grade 2 aim point just because it will make your life easier. Your customers don't care if you have it easy. The prints won't look better because you are more relaxed in the darkroom. (Or will they?)

Likewise, if you get good results with negs that occasionally print on Grade 1 - don't move up to Grade 2 just because it might be better. The difference may be small. Your negs may be useful for carbon or platinum, you have it even easier in the darkroom than I do.

I just made four prints on Grade 4. It was pretty hard for me to keep the tones delicate when the difference between a 10 and 20 second burn (on a 70 second base exposure) made a significant difference in the highlight. (I wanted to make 3 prints but since one was harsh - it's going in the trash). Nope, I am uncomfortable in the nosebleed section...

p.s. In practice I try to keep my CI between about 0.50 to 0.75 - and for the negatives that needed extreme measures I keep a few sheets of Multigrade. (I'm out now have to restock). I like the idea of Selenium Toner for the negs that might need over 0.75. I'll keep that in the back of my mind (going off to sniff some of that right now as a matter of fact).

 

[Stephen Benskin]

I don't know, guys. I think people make too much of this stuff. People like to dump on Adams these days but really, his zone system basics are all people need to make good negatives, as long as we realize targetting a paper range is not always the best way to a fine print. It only works for scenes of average luminance ranges. Even without precise flare factors etc, the basic testing methods in Adams's book are pretty good, and that was with graded paper. VC papers give us even more flexiblity.

I believe when plotting H&D curves and such, it is wise to test in-camera (as Adams suggests) rather than with sensitometers and/or step tablets. In-camera testing introduces some flare, and shutter speed/aperture errors - the kinds of things we ultimately face in the field. Sensitometers are efficient and precise, but represent "lab conditions".

All this business about CI, BTZS, and log exposure ranges to two decimal places?? I highly doubt anybody can control their processes with such precision. In the field, I'd argue anything much smaller than half a stop amounts to quibbling, and is within the normal margin of error. My educated guess is people who measure their film speeds, SBRs and density ranges for development times etc in 1/3 or 1/4 stop increments are fooling themselves, and wasting time instead of mastering printing controls.

I believe there are a number of misconceptions happening here. The Zone System is a form of tone reproduction theory which is why it helps people make good negatives, but who's to say how technical is just the right amount of technical for a person to be? Are the people who don't understand the Zone System deficient in some way while those who understand real tone reproduction theory are wasting their time? It seems to me that it's up to the individual to determine for themselves how much knowledge is sufficient.

Spending time learning tone reproduction theory doesn't necessary wasting the time that could be spent working on one's printing skills. This is a false dilemma. Why not say you can either waste your time cleaning the house or printing? How about you can either spend your time shooting or printing. It's not a zero sum gain situation. It's possible to have many different pursuits.

All this business about CI, BTZS, and log exposure ranges to two decimal places?? I highly doubt anybody can control their processes with such precision. In the field, I'd argue anything much smaller than half a stop amounts to quibbling, and is within the normal margin of error.

This is a strawman argument. It's setting up and then disproving a premise that nobody has made. It's interesting that two rather technical books on sensitometry, Photographic Sensitometry and Photographic Materials and Processes both have chapters on variability and process control. This is a subject that is very much overlook on these forums. Variability in any sample population and ranges in tolerance happens in any process and the deeper I've gone into tone reproduction theory the more this becomes an issue. Using Contrast Index and Log Exposure Range is a way of defining an aim with the understanding that variation happens, and this includes variation in the perception of quality.

A big advantage of CI and LER is the ability to define the materials in a meaningful way and to be able to compare different materials. It's also a way to communicate information. I was once called in to do some consulting for Herb Ritts. Their printer was complaining about the quality of the negatives and blaming the shooting crew. Before I was called in, they shot a MacBeth color chart with a gray card at varying exposures and took the film to a number of labs to be processed. When I got there, they showed me the results and where pointing out which exposure looked best. I told them to ignore those tests and run a sensitometric test through the different labs. What we found out was the lab they were using had as their Normal, +2. I later learned that the lab had bad process control and were using a replenished D-76 line. I've found that when the amount of D-76 replenisher reaches a certain percentage of the stock D-76, the chemistry easily goes out of control. So when the Ritts people started using the lab it was in control and when they started seeing the problem it wasn't. The Ritts people just didn't have the tools to correctly identify the cause of their printing problem. Not long after that, I consulted with the lab and restructured their black and white processing department.

I use graphs, equations, and such measurements as CI and LER on this forum as a communication and teaching tool. I use them to illustrate concepts and solve problems. They are models. The use of them doesn't exclude variance or margin of error, and it would be mistaken to assume otherwise. The use of the graphs and all also doesn't imply that it's necessary to use sensitometric testing to achieve quality results. What I am suggesting; however, is that they are a good way to explain things.

When ever I look at people's suggested normal processing times and temps for a film, I always wonder how do they define their normal conditions? I love how people will suggest processing times and temps to others without any context. But by saying a certain time/temp produces a CI of 0.56 gives information that I can apply to my situation. I don't need to know if the processing time was based using a grade two paper printed on a diffusion enlarger. It's a better, more precise, communication tool.

as long as we realize targeting a paper range is not always the best way to a fine print. It only works for scenes of average luminance ranges.

This is a good example. There's a declarative statement. Now, how can it best be proven? It seems to me a subject luminance range / LER vs print quality graph might do it. Of course I'm not suggesting Michael create one or anything. I'm only saying that graphs are a good way to show the data that proves a premise. Otherwise it's just a bunch of opinions.

I believe when plotting H&D curves and such, it is wise to test in-camera (as Adams suggests) rather than with sensitometers and/or step tablets. In-camera testing introduces some flare, and shutter speed/aperture errors - the kinds of things we ultimately face in the field. Sensitometers are efficient and precise, but represent "lab conditions".

A basic scientific concept is to limit the variables in testing. If I want to know the characteristics of a film, then I need to minimize everything that can confuse the results. Even flare is eliminated in film testing through contacting the samples. Another scientific concept is repeatability. I once tested a film from two different batches. By using a calibrated sensitometer I knew that any differences seen in the two samples was a reflection of the differences in the samples and not some influence from the test. And it's not just my own repeatability but for another person to achieve the same level of meaningful results when they test. Suggesting that scientific testing can't represent the results in actual shooting conditions is a good sound bite, but it misrepresents how science works. It's like how some misuse the scientific use of the term "theory" in such arguments as in "Evolution is just a theory" or "Climate change is just a theory."

Saying "as Adams suggests" is an argument from authority. Shouldn't arguments stand or fall on facts and not who said them?

Here's a funny thing about in camera testing and flare - there almost isn't any flare, and definitely not as much as in shooting conditions. I've attached a graph to illustrate this. There are two factors at work. First 80% of flare comes from the subject. Most in camera testing is done shooting a target with a single tone. Second, even considering average flare, the testing is done at the metered exposure point where flare has little influence on the exposure. The assumption that flare is incorporated into camera testing is almost universal. It sounds like it should be that way, but the use of a simple graph has proven it otherwise. Without such tools, the arguments can become an endless series of unsupported opinion.

Just because there's scientific testing of film doesn't make the test less representative of shooting conditions, and just because someone uses their own equipment doesn't necessarily make the testing more representative of their personal conditions.

 

[Chuck_P]

Here's a funny thing about in camera testing and flare - there almost isn't any flare, and definitely not as much as in shooting conditions. I've attached a graph to illustrate this. There are two factors at work. First 80% of flare comes from the subject. Most in camera testing is done shooting a target with a single tone. Second, even considering average flare, the testing is done at the metered exposure point where flare has little influence on the exposure. The assumption that flare is incorporated into camera testing is almost universal. It sounds like it should be that way, but the use of a simple graph has proven it otherwise. Without such tools, the arguments can become an endless series of unsupported opinions.

A question:
The primer-----------In-camera testing these days, as we know, is the step wedge mounted on top of the film and the film exposed to a single tone target. I do mine outside on a sunny cloudless day in uniform shade so that the target luminance is steady when I make my exposures. But AA did not expose step wedges on film in the camera, he exposed only the negative(s) to a single tone in uniform shade to generate his speed tests and subsequent development times.

The question-----------do you maintain that just as with a step wedge in the camera where you say flare is absent, or nearly so, that flare is also absent, or nearly so, from the negative without a wedge when AA did all his testing, or I should say, when Sexton did the testing under AAs guidance? Is there the same lack of flare condition at the film plane in both instances? Or, does the presence of the wedge itself inhibit some amount of flare from reaching the negative?

Despite what you believe to be a pitfall in AAs ZS test procedure, you can't deny his results. He used lots of film and chemistry his way but speed determinations and curves were generated just the same---by reading the negatives with a densitometer and graphing the curves. The wedge, obviously, saves much film and chemistry in developing the same set of curves.

Just curious.

 

[Bill Burk]

Fair enough.

Spoken like a gentleman. Now are you going to give me a license for my pet fish?

 

[Bill Burk]

Fair enough.

I am so sorry, I couldn't resist.

Here's my real response...


Doesn't mean you're wrong. Without opposing opinions this thread would not be much worth reading.

A couple things you said struck me:

You said it made things worse when you tried fitting negs to paper and I am curious to hear more about that. You've seen some of my thoughts on why that could be absolutely true.

And you wondered about the value of two-place precision: My equipment gives two places. One place would be adequate. Since I have the two places, I find it easier to just write them as displayed. My aim point average is 1.02. Stephen's chart has LER 1.05 and 0.95. If I had rounded to 1.0 I might think my row was exactly in the middle. In fact "my" row is closer to 1.05.

Sensitometry itself is part of my spirit - ingrained since the days of high school and Mr. Ford's print shop being called "pinhead" for not putting a Stouffer reflection scale on the copyboard. So it is part of the pleasure I get from my analog darkroom. It might not be fun for everybody - but it is second nature for me.

 

[Bill Burk]

The question-----------do you maintain that just as with a step wedge in the camera where you say flare is absent, or nearly so, that flare is also absent, or nearly so, from the negative without a wedge when AA did all his testing, or I should say, when Sexton did the testing under AAs guidance? Is there the same lack of flare condition at the film plane in both instances?

There is no flare in a sensitometer because it is contact.
There is very little if any flare in a step wedge on film at the camera.
There is some flare in a real traditional camera test - but not a lot because you are shooting a really, really flat subject.

The criticism of camera testing is based on the fact that you are tossing otherwise separable variables into a mash.

Shutter/lens/light source/flare/light meter - each can be measured with separate tests and added into the sensitometry results.

I agree in principle with Stephen that variables are best excluded.

But I also appreciate that camera tests (for example the Zone System as written in workshop manuals) teach the concepts in a practical way. So I withhold my criticism of the fundamental weakness of the approach for anyone who wants to explore this charted territory for themselves. I appreciate the journey and I respect anyone who wants to follow it for themselves. So if anyone wants to pretend it is 1884 again and I can offer assistance with the techniques of the time, I'd be thrilled to help.

 

[Stephen Benskin]

A question:
The primer-----------In-camera testing these days, as we know, is the step wedge mounted on top of the film and the film exposed to a single tone target. I do mine outside on a sunny cloudless day in uniform shade so that the target luminance is steady when I make my exposures. But AA did not expose step wedges on film in the camera, he exposed only the negative(s) to a single tone in uniform shade to generate his speed tests and subsequent development times.

The question-----------do you maintain that just as with a step wedge in the camera where you say flare is absent, or nearly so, that flare is also absent, or nearly so, from the negative without a wedge when AA did all his testing, or I should say, when Sexton did the testing under AAs guidance? Is there the same lack of flare condition at the film plane in both instances? Or, does the presence of the wedge itself inhibit some amount of flare from reaching the negative?

I assume the step tablet is in contact with the film. If so, then it is a non flare test.

Generally speaking, average flare tends to increase or decrease 1/3 stop per stop luminance range. A one stop flare factor means that flare adds one stop of exposure to the lowest exposure. In the standard exposure model for 2.20 log subject luminance range ( 7 1/3 stops) using a 125 speed film, the shadow exposure will be 0.0034 mcs. One stop of flare will bring it up to 0.0068 mcs. The exposure at the metered exposure point will be 0.064 mcs. Add .0034 mcs of flare to 0.064 and you get 0.674 which isn't a big change.

This is the condition in the camera image example I've included again. You can see there is very little flare at the metered camera point ( ~ 3% vs 100% in the shadow) and this is with a full 2.20 LSLR. When doing an in camera test of a single toned subject, the card is metered and stopped down. The flare at the metered exposure point doesn't change.

I've also attached an example with a 4 stop subject luminance range. It's the shortest my program can do. You can see how flare is diminished as the luminance range is reduced. Now imagine flare from a single toned subject.

Despite what you believe to be a pitfall in AAs ZS test procedure, you can't deny his results. He used lots of film and chemistry his way but speed determinations and curves were generated just the same---by reading the negatives with a densitometer and graphing the curves. The wedge, obviously, saves much film and chemistry in developing the same set of curves.

You've always misunderstood my concern about this. It's not that you can't get good results. It's that you aren't getting what you think you are getting. It's good that the test is practically devoid of flare, but if you assume there's flare and there's not, it will skew the results. It comes down how to interpret the data. A film curve should represent the characteristics of the film and that means without the influence of flare. This means that you have to make adjustments for exposure conditions when extrapolating data from it - such as film speed and desired negative density range. (One advantage of using the multiple quadrant tone reproduction curve is the ability to separate the camera exposure from film curve.)

With the ISO speed standard, that means placing the speed point 3 1/3 stops down from the metered exposure point instead of 4 1/3 stops which represents the actual shadow range. This difference in the point of measurement adjusts for one stop of flare with the camera exposure on a non-flare film characteristic curve. If you don't adjust for this and measure the film at the the 4 1/3 stop point, the resulting film speed will be one stop slower.

So, as the in camera test is virtually flare free, and the Zone System says to stop down from the metered exposure point 4 stops, it suggests that you are interpreting a non flare testing condition without factoring in the adjustment. Since the Zone System only assumes 4 stops (vs the 4 1/3 stops for the ISO standard), the difference we would expect to see between the ISO film speeds and the film speeds from the Zone System tests would be around 2/3 of a stop. And this is exactly what we are seeing.

As Seinfeld used to say, "not that there's anything wrong with that." This is were you tend to misunderstand my point. Doing this doesn't hurt image quality. You might recall how I tend to compare the Zone System testing results to the ASA speeds prior to 1960. Speeds were then a stop slower than they are today. Right there is the validation of quality from ZS testing. Speeds were a stop lower and quality was still good. You might also recall my point that while the ASA standard changed in 1960, Zone System testing didn't. This means that prior to 1960, film speeds from Zone System testing would have been generally equal with the ASA speeds. What we are basically discussing is that one of the testing methods changed and another didn't, which means they are no longer directly comparable. The reason for the change in the 1960 standard was to eliminate a chunk of a safety factor that they felt was no longer needed. A safety factor isn't a bad thing to have and there's nothing wrong with that.

There are a number of additional factors that aren't addressed with Zone System testing, but flare has the greatest influence by far.

My constant harping on the subject is to make people aware of how the system works. I think this is important to know. It's about how way we perceive things even though it might not have an affect on how anyone works. Understanding the Earth goes around the Sun and that the sunrise is just an illusion may not change the fact that I have to get up too early for work, but it does affect how I see the world. Think about how many theories have been created to explain why ISO speeds differ from the "true" film speeds obtained from personal testing. Now you know it's because the testing parameters are different - problem resolved, conspiracy theories vanquished. Yes, "film speeds" obtained by Zone System testing are technically wrong, but there is nothing wrong with them as EIs.

The question of interpreting data for shooting conditions from data obtained from testing conditions also plays a part in the Zone System's approach in determining negative density range. In this case, there is an adjustment made, but it's never explained. So, while you get what you need, you aren't getting what you think.

I hope this has clear a few things up.

 

[Bill Burk]

Suppose important highlights fall on zone XI. The zone system says use N-3 to bring them down to zone VIII, which will print with detail. The problem is, when you contract a zone XI highlight (which must contain luminances above and below that for there to be visible detail) to zone VIII, you lose most of the local contrast in the negative.

I appreciate your input and know you've been there and I want to hear more of your experiences.

I am lucky some days (foggy Pacifica) to have 4 stops subject brightness. Just now I printed another flat neg. 0.53 is my negative density range. And I had to print it on Grade 3 because I used my last sheets of MG last night on a more precious print. I was lucky this neg exists too and you know, I have to have it framed tomorrow. So I printed this one high key and heavily burned the edges just to get something pleasing.

It was roll film - and not developed long enough for the subject brightness range. I tend to develop roll film to CI 0.62 - have to check my notes to see what I did here. But I would have been better off tonight if I had developed this roll to fit my paper knowing it was a short-range day.

 

[Bill Burk]

Hey Stephen, Merry Christmas

the Earth goes around the Sun.

The argument used to be.... If it did that, we'd be able to measure the parallax.

Oh yeah, those stars are pretty far away.

Bill