AA's Value I density targets

[takilmaboxer]

Based on experience I would advise caution. The Zone System can become a rabbit hole...

 

[markbau]

Based on experience I would advise caution. The Zone System can become a rabbit hole...

No worries there. I've been using the zone system for about 40 years. I know some people treat it as the gospel according to Saint Ansel but it is still a good teaching tool and in the field always gives me useful densities in the shadows and highlights. If you really want to go down a rabbit hole buy a copy of "Beyond The Zone System"

 

[Sirius Glass]

I use only the light metering portion of the Zone System to bring out selected shadows. I have never used the expansion or compression for film development since I do not need it with modern films.

 

[Raghu Kuvempunagar]

as I purchased a densitometer (for alt process) thought I'd see how close my zone 1 is to AA's recommendations.

I assume that, to rule out densitometer reading error, you've measured the density of a target such as Stouffer wedge and verified that the readings are fine.

An effective alternative to towel or black card is a diffuser mounted on the lens as a filter. Something that one uses to pre-flash film on location. For 35mm format film, Nikon ES-2 digitizing adapter is very convenient for these purposes.

 

[Nicholas Lindan]

For 35mm format film, Nikon ES-2 digitizing adapter is very convenient for these purposes.

Or a slide duplicator adapter on a bellows. For extra fun (or extra confusion) a 35mm step tablet can be mounted in the duplicator.

A one-tone/zone-per-frame regime gives the best results as then you can use a bench densitometer.

If using the step tablet you have to project the negative and measure the density at the easel. A reference uniform grey negative needs to be taken and used to zero the readings for each of the projected step tablet patches - the illumination from the enlarger light source isn't all that uniform and the illumination in the duplicator may also be non-uniform.

I didn't find the zone system per se improved my photographs - but going through all the folderol of zone system testing improved my technique resulting in consistent results, and that did improve my photographs.

 

[MattKing]

MattKing. First of all, using a towel could be problematic unless the towel is stretched tightly over a flat surface, if you just drape a towel over a chair or something you will get folds that will have shadows in them, you need a very flat surface for a test such as this as you don't want subtle variations caused by a not perfectly flat surface. Regarding the choice of a black card. I fail to see what difference it would make. I'd be more concerned with using a lighter card as that may introduce flare. The main concern is to take a meter reading and then "place" the reading on zone I.

Mark,
My concern is that the card could be of such low reflectivity that it doesn't reflect enough light to give you a reliable meter reading.
A card that is way more than 4 zones darker than a mid-grey card.

 

[markbau]

I use only the light metering portion of the Zone System to bring out selected shadows. I have never used the expansion or compression for film development since I do not need it with modern films.

I agree totally although occasionaly I have given +1 development for an extremely low contrast scene.
I have found that giving a pre-exposure is a much more elegant thing to do with a high contrast scene.
I should add that in AA's later years at his Yosemite workshops he was saying that contraction, with the films available in the mid 1970s was not very useful. This came from a friend who did two of his workshops. He also picked up a 8 x 10 print of moonrise over half dome (printed by Ansel) for $20 that he recently sold for several thousand dollars.

 

[markbau]

I assume that, to rule out densitometer reading error, you've measured the density of a target such as Stouffer wedge and verified that the readings are fine.

An effective alternative to towel or black card is a diffuser mounted on the lens as a filter. Something that one uses to pre-flash film on location. For 35mm format film, Nikon ES-2 digitizing adapter is very convenient for these purposes.

I have a 12 month old Heiland densitometer (purchased new) It still repeats the calibration film and print that came with it. It also agrees with a calibrated Kodak step wedge that I bought 30 years ago for a silly amount of money.

 

[bernard_L]

I'd be concerned about the role played by the black target - reflectivity, surface sheen, etc. - and the metering technique for a reading from a black subject.
In an "idealized" world, a truly black subject would give you no reading whatsoever, no matter what the light levels are.
But as we aren't discussing telescopes and photographing black holes, it seems to me that it is better to use something like a grey towel with lots of texture instead.

It isn't necessary to use a grey card - anything with a reasonable amount of reflectivity and some observable texture - a grey towel being an example - is a good subject.
You then place your reading from that subject on the Zone that you are seeking to target.

A point I made 20 posts ago, and that was shrugged off as irrelevant by the OP.
To elaborate, I'd have an additional concern with the "black" target. Depending on the nature of the target (more likely to be printed than, e.g. carbon black), its reflectivity in the near-IR is not specified, and might be higher than in the "visible".
https://www.researchgate.net/figure...-and-dark-colors-with-variable_fig1_263017059
And, depending on the photocell in the light meter, (especially but not only CdS) it might have substantial response in the near-IR.
https://www.photrio.com/forum/threads/spectral-response-of-meter-cells.111298/#post-1472349
https://www.researchgate.net/figure...ral-response-to-solar-spectrum_fig3_237202290
These IR properties, combined, might result in underexposure of the target in the "normal" range 450-650nm. Which is a possible explanation for the anomaly seen by the OP.

 

[markbau]

Mark,
My concern is that the card could be of such low reflectivity that it doesn't reflect enough light to give you a reliable meter reading.
A card that is way more than 4 zones darker than a mid-grey card.

Well my black card was nowhere near 4 stops darker than my 18% grey card. I have a set of Vello photographic cards, white/mid grey/black. The mid grey card actually says "medium" and doesn't state that it is 18% grey. Anyway. If I measure the 3 cards in the same light with a Pentax digital spotmeter I get:
BLACK 2 2/3
MID 5 1/3
WHITE 7
4 1/3 stops from the black to the white card. The black card is only 2 2/3 stops darker than the mid grey car.

I've never had cause to doubt the accuracy of a shadow reading with my spotmeter.

 

[RalphLambrecht]

Why

Good question!

 

[markbau]

A point I made 20 posts ago, and that was shrugged off as irrelevant by the OP.
To elaborate, I'd have an additional concern with the "black" target. Depending on the nature of the target (more likely to be printed than, e.g. carbon black), its reflectivity in the near-IR is not specified, and might be higher than in the "visible".
https://www.researchgate.net/figure...-and-dark-colors-with-variable_fig1_263017059
And, depending on the photocell in the light meter, (especially but not only CdS) it might have substantial response in the near-IR.
https://www.photrio.com/forum/threads/spectral-response-of-meter-cells.111298/#post-1472349
https://www.researchgate.net/figure...ral-response-to-solar-spectrum_fig3_237202290
These IR properties, combined, might result in underexposure of the target in the "normal" range 450-650nm. Which is a possible explanation for the anomaly seen by the OP.

So are you saying AA's test procedure is basically flawed?
AA says to use a middle grey surface for films rated ASA 50 or slower and to use "a darker surface" for faster films as it will give a better range of apertures and shutter speeds. Although he doesn't state it, he doesn't warn against using a black target for these tests.

I should add that my Pentax spotmeter is a Zone VI modified meter.

 

[RalphLambrecht]

What do you mean "technical error"? And what do you mean I am 3 stops off. AA wasn't expecting a density of 0.10 when rating it at its box speed. Later in the book he says he rates TX (Not TXP) at EI 200 so it's fair to say that his rating at EI 200 got him 0.10. The spot meter I used has recently been checked by a camera tech and found to be within factory specs. The camera was checked a year ago for shutter accuracy and I've never questioned it. The light source was constant.
AA says 0.09 - 0.11. I got 0.05 at EI 200 which is which is 1 1/3 stop from 0.09. Not 3 stops. (I don't know anyone who rates B&W film at its box speed.

a transmission density difference of 0.9 stops have little to do with an exposure difference of 3 stops.

 

[markbau]

a transmission density difference of 0.9 stops have little to do with an exposure difference of 3 stops.

Ralph, I'm sure you are familiar with H&D curves. The most important log value for photographers is 0.30 as it represents the important 1:2 relationship. To quote AA "An increase of 0.30 represents a doubling of opacity; on the log E scale of the H&D curve, an interval of 0.30 corresponds to a doubling of exposure - a one stop change on the camera, or a one zone change non luminance on the exposure scale.

So why are you asserting that 0.90 have little to do with an exposure difference of 3 stops? One stop is 0.30, 2 stops 0.60, 3 stops 0.90.

 

[john_s]

......

I should add that my Pentax spotmeter is a Zone VI modified meter.

You might want to check your meter. I bought two of them from Zone VI so I could have a matched pair and check one against the other (for "accuracy"). They were handled carefully. They differ from each other by a lot, a stop at one end of the scale, less at the other end. Neither match several newer spot meters that all match each other closely.

Paul Butzi had an interesting article about the Zone Vi modification (probably available on the wayback machine since his web site is very different now). It was backed up by measurements and was not positive.

 

[Raghu Kuvempunagar]

So why are you asserting that 0.90 have little to do with an exposure difference of 3 stops? One stop is 0.30, 2 stops 0.60, 3 stops 0.90.

Where's this number 0.9 coming from? I can't quite see it in the densities you reported in OP.

 

[Sirius Glass]

I agree totally although occasionaly I have given +1 development for an extremely low contrast scene.
I have found that giving a pre-exposure is a much more elegant thing to do with a high contrast scene.
I should add that in AA's later years at his Yosemite workshops he was saying that contraction, with the films available in the mid 1970s was not very useful. This came from a friend who did two of his workshops. He also picked up a 8 x 10 print of moonrise over half dome (printed by Ansel) for $20 that he recently sold for several thousand dollars.

When I finished graduate school, I had finally brought the latest Minolta slr and several lenses. I was only shooting slides and had no plans or ways to get into a darkroom. The people I worked with set up a week in Yosemite class taught by Ansel Adams. Well I knew that N+1, N+2, N-1, ... would not work for 35mm film maybe 120 or 4"x5", [I never thought of renting equipment, who knew?] and besides I was shooting slides. The most I would do would be to crop a slide and mount it in glass or get a Cibachrome print made. So I was so GD smart that I said no thank you. Many decades later I took a week long class with Alan Ross and learned a lot. Almost the same, but in a way really not.

 

[Sirius Glass]

Alan Ross is a really nice guy too.

Alan Ross has a nice way of clearing out the unnecessary to keep the message and the methods as simple and direct as possible. I was not up to speed on PhotoShop so I was not able to follow some of what he was doing.

 

[Bill Burk]

Considering you got 0.05 at 200 and you wish for at least 0.09 - the difference is 0.04 density.
Guessing roughly 0.5 contrast you would like to give 0.08 greater exposure. A whole stop would be 0.3, you want to increase exposure about a third stop. EI 160 for Tri-X is not a wrong test result. That’s only one third stop greater exposure than “standard” Zone System test results.

 

[Stephen Benskin]

Testing results that are outside the expected range, are most likely the result of an undesirable factor. One of the reasons why it's important to limit the number of variables in testing is to eliminate as many variables as possible. Film has already been scientifically tested resulting in an ISO speed rating. Giving what is known about the methodology of Zone System testing and preponderance of the stated results, the resulting EI should be around 2/3 +/- 1/3 of a stop below the ISO speed. The OP's results indicated the EI is around 100 to 125. I was able to determine this using a TX 120 film curve. This is outside of the expected range of results, so it is probably due to an experimental error.

Whenever there is an expected experimental error, the next step is to evaluate the testing process; however, the testing methodology presented by the OP is lacking detail. This naturally resulted in some good inquiries from other posters. Redoing the test can possibly correct any mistakes in testing, such as miscounting f/stops, not zeroing the densitometer, inaccurate metering, and any irregularities in processing. If retesting produces a more reasonable result, it just means whatever the mistake causing the bad results wasn't repeated or that other mistakes were made that countered the original mistakes.

What it won't do is answer any questions or fix is any potential fundamental problems with the methodology. These factors can be accumulated too. For instance a light source with a color temperature is used that different than the standard. The photo cell on the exposure meter might have a lower or higher spectral sensitivity to the light source. The film could have a different sensitivity to the light source. The target could be absorbing reflecting the spectral range differently than it would with the standardized color temperature. Depending on how the combination of materials respond, the results can be greater than, less than, or the same as if the standard color temperature was used.

Good testing methodology would have eliminated most of these variables making it easier for evaluating potential error causing factors. Testing methods such as the Zone System does not. Simply determining an important part of determining film speed such as the degree of processing is missing. Placing the resulted density within a relationship of the other densities on the film curve is also missing. If it was a good testing method, the problem the OP is having should have been easily resolved.

 

[Maris]

I'm a bit confused about what the OP test actually reveals.
The film can't be wrong about how it responds to a given exposure.
The developer can't be wrong if its effects are even over the entire film.
So an anomalous result can only be due to cumulative instrumental errors in the densitometer plus the light meter plus the camera. And the errors can be linear or non-linear, all one way, or a diabolical combination of plus and minus deviations.

In the past I've tested film and got strange results. The three procedural changes that have improved results for me are:
Never use a light meter in setting up a film test. Instead use a film to calibrate a light meter.
Keep the shutter speed constant and change exposure by changing lens apertures.
Change aperture values by always turning the aperture ring in the same direction to avoid mechanical backlash.

 

[RalphLambrecht]

I didn't quite get you. Isn't 0.10 - 0.01 = 0.09 and not 0.9?

Good catch. I fell for it too.

 

[RalphLambrecht]

Based on experience I would advise caution. The Zone System can become a rabbit hole...

Yes but usually you leave that whole a lot smarter than you entered it.

 

[Bill Burk]

Testing results that are outside the expected range, are most likely the result of an undesirable factor…
Whenever there is an expected experimental error, the next step is to evaluate the testing process.

The error is kind of “significant”. It’s winter here and it’s hard for me to keep developer at 20-degrees C here. Wonder if the developer cooled down in the tank during the process

 

[markbau]

The error is kind of “significant”. It’s winter here and it’s hard for me to keep developer at 20-degrees C here. Wonder if the developer cooled down in the tank during the process

That's a slightly insulting question, having developed films for 40+ years including 10 working in a pro lab. I live in Australia where it is the middle of summer although I'm not sure what the season has to do with film development temperature. I measure film developer 3 times, once just before it goes in, mid way through development and then after it is poured out, the drift is usually 0.5 Degree C.