Why is Zone System EI often about half rated ISO/ASA?

RobC · Aug 27, 2015

Bill Burk said:
If I were to explain what I think you have done, you appear to be developing to something like N-1 and using variable contrast paper to make up for any different subject luminance range that you encounter.

As I've said previously, I use roll film and therefore don't use N+ or N- because I have lots of different SBRs on a single roll. As long as you try to convert my method to terms that you use in your method, I think you will fail.My methodology doesn't require to use any of those terms. It just requires a practical photographic evaluation. You should try it, its very liberating.

And check out following for some contrast control with your graded paper.

http://www.digitaltruth.com/data/drbeers.php

Xmas · Aug 27, 2015

RobC said:
what the meter reading is, is always a mid point after calibration.

A very abstract viewpoint the galvanometer on my light meter is calibrated in absolute light units, the circular slide rule calculator is calibrated in absolute units, ISO and zones (with a K offset).

When you point it at something it takes an average of the scene if the scene is a zone 1 shadow the reading will be the average of that scene, ie a mid point of the zone 1 Area.

If I pointed it at a zone two area it would be a zone 2 mean.

And yes that is how I meter contrasty scenes.

Stephen Benskin · Aug 27, 2015

RobC said:
I think the confusion here is that previous posts are suggesting that zone V is 4 stops UP from 0.1. Well that is the target but meters don't use an offset from 0.1 UP from the bottom of the curve. They use an offset Down from the reading they take to a midpoint.

Sorry, but you have a fundamental misunderstanding of how exposure and meters work.

Stephen Benskin · Aug 27, 2015

Ian Grant said:
There's two or rather 3 different approaches to exposure being discussed in this thread.

There's the Theoretical approach of Stephen Benskin, the practical approach of the Zone Sstem and the Over-exposure approach of others.

The original question was why are Zone System EIs often times half of the ISO speed. The question is about theory. You can't answer that with "it works for me."

RalphLambrecht · Aug 27, 2015

Stephen Benskin said:
The original question was why are Zone System EIs often times half of the ISO speed. It's a question about theory. You can answer that with "it works for me."

true,but,I answer it with:because sadow exposure may better to be targeted at Zone IV rather than ZoneIII and ZoneI denaity is closer to 0.17 then0.1, but that's just me.YMMV.For me, it all works a lot better ith a bit extra exposure and I don'tdo any Zone System work without a tripod anyway.a loer film speed poses no issue to me.

markbarendt · Aug 27, 2015

Bill Burk said:
If you put a Zone System sticker on your meter, you align Zone V with the main meter dial arrow.

Now there is nothing stopping anyone from choosing an Exposure Index that allows them to place shadows on Zone I with a direct reading. (Or picking any favorite Zone and making the Exposure Index to fit). But that's not your usual teaching.

With a needle indicating the way this works perfectly. With a needle and a sticker the meter is calibrated to all the zones with one EI setting. To make this work with a digital meter takes a correction for each zone.

markbarendt · Aug 27, 2015

RobC said:
No it isn't zone V.
I think the confusion here is that previous posts are suggesting that zone V is 4 stops UP from 0.1. Well that is the target but meters don't use an offset from 0.1 UP from the bottom of the curve. They use an offset Down from the reading they take to a midpoint.

What you are describing (down) is part of the zone system's concept of and language for "how life works".

That's not really how life works.

The calibration point for the ZS is 0.1, the rest is just math.

markbarendt · Aug 27, 2015

RalphLambrecht said:
true,but,I answer it with:because sadow exposure may better to be targeted at Zone IV rather than ZoneIII and ZoneI denaity is closer to 0.17 then0.1, but that's just me.YMMV.For me, it all works a lot better ith a bit extra exposure and I don'tdo any Zone System work without a tripod anyway.a loer film speed poses no issue to me.

Yes, in the real world we can calibrate any way we please.

RobC · Aug 27, 2015

Stephen Benskin said:
Sorry, but you have a fundamental misunderstanding of how exposure and meters work.

Cleary that proves you don't need to know any of this geekery then.
The simple logic of that for you is that if you don't understand it but can still produce properly exposed negatives and the print of zones patches when you have a fundamental misunderstanding of how exposure and meters work, then clearly that understanding is totally superfluous.

Shot yourself in the foot I think.

Bill Burk · Aug 27, 2015

markbarendt said:
With a needle indicating the way this works perfectly. With a needle and a sticker the meter is calibrated to all the zones with one EI setting. To make this work with a digital meter takes a correction for each zone.

You might have to count off in your head or on your fingers. It's easy enough to change the settings on the camera if you look at the f/stop ring or shutter speed dial while counting stops to open or close from the main reading that you are placing.

The Sekonic L758DR has a mode which provides "clipping point" indications. I have found that this meter can be adapted to Zone System use by adjusting the clipping points to fall on Zone I and II in the shadow, and Zone VIII and IX in the highlights.

L758DR Zone Sticker

Some hand-held charts have been devised since the beginning of the Zone System. For example this one (careful when ordering to clarify what the seller is sending you: the book, the dial or both - I was lucky and the seller sent me both).

Zone-Systemizer-Creative-Photographic-Control

RobC · Aug 27, 2015

If we can't add or subtract 2 or 3 stops in our heads without resorting to using a calculator then I think we're in trouble.

Bill Burk · Aug 27, 2015

RobC said:
As I've said previously, I use roll film and therefore don't use N+ or N- because I have lots of different SBRs on a single roll. As long as you try to convert my method to terms that you use...

I'm translating what you do to terms that I use in order to find something we can talk about in common. Zone System "N" terms and "Place" and "Fall" are all we need. In 1963, Minor White wrote about what you are doing. I think you would like this book because it is designed around the visual match method. It's only 111 pages and all good stuff. I have only found one error in it, a few Linotype slugs were dropped and put back in the wrong place. It's funny reading Page 43 until you see what happened.

Minor White - Zone System Manual

Minor White recommends N - 1 1/2

Meanwhile, as long as you like dogs, we have something in common.

RobC · Aug 27, 2015

Bill Burk said:
I'm translating what you do to terms that I use in order to find something we can talk about in common. Zone System "N" terms and "Place" and "Fall" are all we need. In 1963, Minor White wrote about what you are doing. I think you would like this book because it is designed around the visual match method. It's only 111 pages and all good stuff. I have only found one error in it, a few Linotype slugs were dropped and put back in the wrong place. It's funny reading Page 43 until you see what happened.

Minor White - Zone System Manual

Minor White recommends N - 1 1/2

Meanwhile, as long as you like dogs, we have something in common.

You're in luck, I do so long as they don't bite.

markbarendt · Aug 27, 2015

RobC said:
Cleary that proves you don't need to know any of this geekery then.
The simple logic of that for you is that if you don't understand it but can still produce properly exposed negatives and the print of zones patches when you have a fundamental misunderstanding of how exposure and meters work, then clearly that understanding is totally superfluous.

Well, it seems to me, that all it proves is that you, RobC, don't need the geekery; that's ok and you are not alone. Not everybody wants to know the geekery.

It doesn't prove that Stephen or the rest of us can or should live in ignorance of the way things really work.

Living without the geekery means that one is dependent on the rules of the system the individual uses and it limits the options one has.

What the geekery does is allow more options for figuring out a camera setting in any given situation.

Knowing the geekery means I can use any meter that's handy, in any situation, and do it efficiently and accurately. If it's my Sekonic L-358 that's handy great, my F100 great, my F5 great, my RB67 with the meter in the prism great, ...

Knowing the geekery also means I can help people I'm hanging with understand why their metering method might be giving a different result than expected, why my shot turned out as expected and their's didn't.

Muihlinn · Aug 27, 2015

If you read the ISO standard for measuring film speed, and their lightning conditions, it becomes evident

Stephen Benskin · Aug 27, 2015

RobC said:
Cleary that proves you don't need to know any of this geekery then.
The simple logic of that for you is that if you don't understand it but can still produce properly exposed negatives and the print of zones patches when you have a fundamental misunderstanding of how exposure and meters work, then clearly that understanding is totally superfluous.

Shot yourself in the foot I think.

Just being the gate keeper against BS. I've often discussed the tolerances in photography. If shown graphs depicting it. You don't need to know the geeky stuff. Who said you did? This is about inaccurate claims.

I'm reminded of a story Phil Davis once told me. Phil reviewed a proposed book for his publisher. In the section on film contrast, the author described how he had a difficult time in his new darkroom calibrating the contrast of his film to what he had in his old darkroom. He did test after test. Finally he concluded that the table /sink he was processing the film on was 6 inches higher than the one in his old darkroom. Why should this matter? What evidence does the author have to substantiate such a claim?

Just because someone says it's so doesn't make it so.

Old-N-Feeble · Aug 27, 2015

Stephen Benskin said:
Just being the gate keeper against BS. I've often discussed the tolerances in photography. If shown graphs depicting it. You don't need to know the geeky stuff. Who said you did? This is about inaccurate claims.

I'm reminded of a story Phil Davis once told me. Phil reviewed a proposed book for his publisher. In the section on film contrast, the author described how he had a difficult time in his new darkroom calibrating the contrast of his film to what he had in his old darkroom. He did test after test. Finally he concluded that the table /sink he was processing the film on was 6 inches higher than the one in his old darkroom. Why should this matter? What evidence does the author have to substantiate such a claim?

Just because someone says something doesn't make it so.

Nuh-uh!!

RobC · Aug 27, 2015

My information is that my spot meter bases it calculations on the expectation that the mid point of the film should receive 0.1 lux.seconds of exposure (adjusted for film speed) and that is calculated back from the light reading it takes in cd/m^2 and NOT up from a negative density of 0.1.

You can argue all you like that one provides the correct exposure for the other but as I have already said, the meter bases its calculations on hardcoded data and if it says it adjusts to provide for 0.1 lux.seconds exposure on the mid point then I believe it and not some theorist wanting to argue their own formluas. The calculation is down from the reading to the mid point.

Stephen Benskin · Aug 27, 2015

RobC said:
My information is that my spot meter bases it calculations on the expectation that the mid point of the film should receive 0.1 lux.seconds of exposure (adjusted for film speed) and that is calculated back from the light reading it takes in cd/m^2 and NOT up from a negative density of 0.1.

You can argue all you like that one provides the correct exposure for the other but as I have already said, the meter bases its calculations on hardcoded data and if it says it adjusts to provide for 0.1 lux.seconds exposure on the mid point then I believe it and not some theorist wanting to argue their own formluas. The calculation is down from the reading to the mid point.

The meter doesn't work in isolation. The film speed and how it's determined is part of the equation.

Once again, Hg is 8/ISO.

markbarendt · Aug 27, 2015

RobC said:
My information is that my spot meter bases it calculations on the expectation that the mid point of the film should receive 0.1 lux.seconds of exposure (adjusted for film speed) and that is calculated back from the light reading it takes in cd/m^2 and NOT up from a negative density of 0.1.

You can argue all you like that one provides the correct exposure for the other but as I have already said, the meter bases its calculations on hardcoded data and if it says it adjusts to provide for 0.1 lux.seconds exposure on the mid point then I believe it and not some theorist wanting to argue their own formluas. The calculation is down from the reading to the mid point.

A meter knows nothing until the button is pushed. At that point it only knows a luminance level.

It still has no clue of how that raw data relates to the world around it or what camera setting to suggest; that raw data is just a number without any context.

Until the meter's EI/ISO/film speed is set by the user, the meter can't provide a meaningful answer/readout/camera setting. (With the exception of pure dumb luck in that the setting on the meter from the factory happens to be set at the EI we need/want.)

The act of a person setting a meter's EI/ISO/film speed setting calibrates that meter to the standard the user has chosen, to a reference point on the film curve. Said another way, "the user has set the offset".

By setting the meter's EI/ISO/film speed "we" tell the meter how far the suggested/displayed camera setting should be from a/any given point on the film's curve.

At this point (when the meter knows both the luminance and the offset) the meter can suggest a meaningful camera setting.

Stephen Benskin · Aug 27, 2015

markbarendt said:
Well, it seems to me, that all it proves is that you, RobC, don't need the geekery; that's ok and you are not alone. Not everybody wants to know the geekery.

RonC doesn't appear to think lenses are too geeky based on this responses over at the Spread of Light Through Lenses thread. I guess geeky is relative.

markbarendt · Aug 27, 2015

Stephen Benskin said:
RonC doesn't appear to think lenses are too geeky based on this responses over at the Spread of Light Through Lenses thread. I guess geeky relative.

Xmas · Aug 27, 2015

RobC said:
My information is that my spot meter bases it calculations on the expectation that the mid point of the film should receive 0.1 lux.seconds of exposure (adjusted for film speed) and that is calculated back from the light reading it takes in cd/m^2 and NOT up from a negative density of 0.1.

You can argue all you like that one provides the correct exposure for the other but as I have already said, the meter bases its calculations on hardcoded data and if it says it adjusts to provide for 0.1 lux.seconds exposure on the mid point then I believe it and not some theorist wanting to argue their own formluas. The calculation is down from the reading to the mid point.

Hi Rob

My meter is the same if you point it at a zone 5 area and tell the meter it is zone 5 it gives the 'correct' exposure for zone 5.
It is however too difficult for me to do that. So I only ever spot zone 1...

I'd merely note that zone 5 is not always not always the mid tone... But it is always zone 5.

Bill Burk · Aug 27, 2015

I'd like to offer a compromise position that will allow us to move forward on this discussion...

RobC has calibrated for 10 stops of subject luminance range, using Ansel Adams' 10 Zone System patches as examples of what to visually expect.

Then RobC uses a high Zone for most of his exposure determinations, which - for his practical purposes - is a highlight calibration.

As far as standards are concerned, there is enough documentation that the shadow 0.10 density point is used to identify the 0.3 x average gradient point... where meters are calibrated to by standards. The standards amazingly passed committee and peer review... shadow calibration stuck.

When it comes to what's practical:

RobC's plan to "Develop to N-1 1/2" (I know you don't necessarily like that terminology but its how I would explain it to a student, and it's Minor White's words)... And then select and meter a high value such as VIII or IX and "Place" exposure on the appropriate high Zone...

Is a good plan: assured to give relatively consistent print times and contact sheets where exposures are not all over the place.

Bill Burk · Aug 27, 2015

Here's another random observation...

I have a selenium cell incident meter, an old Sekonic.

Without the white dome, the meter reads three stops higher than with the white dome.

So even though the dome is colored white...

It's cutting about three stops and the meter cell sees gray.

Why is Zone System EI often about half rated ISO/ASA?

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