Exposure

Yes, that is indeed the general idea. We decide in what zones parts of the scene must end up in (within the limited possibilities), and adjust exposure and processing such that a given, metered luminance difference ends up as our desired zone difference.

Zones are not EV values or such. They are part of our previsualisation. They are what we want the print to look like. Zone 0 is black, no detail. Zone V is a middle grey between black and featureless white. What EV values or how many stops apart in the scene they may be determines how we must expose and develop. But the zones are what we assign those luminance values/differences to. They are not luminance values (you can make a full range print - all zones - from high and low light scenes alike). Nor is the difference between zones a fixed difference in luminance values.

That is the entire point of the zone thing: we take control. We do not let a scene dictate how it will look like in our rendition of it. Who cares that the difference in luminance between a black cat and white snow is so many stops. We want them both to look grey, so we make it happen. (A bit too ambitious, since there are limits to what we can do, selecting film, exposure development, print grade, paper developing, etc.)

We have to know how many stops difference there is, yes. And we have to know what film to pick, how to expose and how to process and proceed beyond that. But knowing EV values does not make zones have a fixed value.

You say that each zone is one stop apart. Maybe, if you do expose for middle grey and do nothing special, and use a straight forward, long straight curve film with no toe and no shoulder. Vary ythose parameters a bit, and zones no longer are one stop apart. have a film with distinct toes and shoulders, and even with straight processing but adjusted exposure, the differences aren't a fixed value anymore. Et cetera.

All not important, and way too complicated, when you use a digital camera. At least, that was you point, wasn't it? Zone system is nevertheless a great teaching tool, that helps understand exposure and what comes after that, whether it is in fluids or on a computer. Much more than looking at a screen on a camera can.

Zone system is not very practical. It has severe limitations. But that is another matter.

Well, you have gotten me at the semantics. I don't feel comfortable here, my english is not as good as I would like.

Personally, the word "Zone" is always related to the print, or what is the same, to the grey shaded scale that are the Zones, from 0 to X. It is always the print.

When I'm at the scene, I think (visualize) the scene in terms of Zones. So when I said

But it doesn't mean that in the scene there must be one stop metered differences between the Zones (or real life objects)

I`m obviously saying that the stops belong to the scene metering and not to the Zones or description of Zones. There is obviously a relationship, but not closed or precise, this is the important thing.

After reading your posts I assume there must be an Adams phrase that states what you say (don't have the book here), but even if so, Ctein`s words came into debate... the one-stop-equal-to-one-Zone is "by definition", it must be taken with a pinch of salt.

And, what if so? It doesn't change Adams` Zone system. The method is perfectly feasible, being -or not- one zone=one stop (step of gray shade/exposure, I mean).

I think Adams had a printed grey scale attached to his own meter (Weston?), or he recommended to have it this way. So I assume the aim was (very likely) to visualize the values with an easy, practical method. But think on it... does it makes sense for any other reason? And again, what if the meter, instead of reading 18% reflectance is actually reading 12%? And the most important, does it change the sense or the usefulness of the Zone System?

if you don't have a fixed exposure spacing (or at least a well-defined set of spacings) how can you possibly arrive at an exposure that places the tones where you want, relative to each other?

Yes, of course you are right here. Tests must be done to get the tones or values, with precise spacings, one stop exposure differences to get each Zone.

This is actually the closest relationship between the Zones and the one stop exposure in the scene; but think that all the tests must be done under controlled conditions and with the same grey card (towel or whatever), where the real scene is quite variable, so the "Definition of Zones" cannot be taken as a precise metering reference.

... "Definition of Zones"...

"Description of zones" (table of), I mean.

They are not luminance values

Yes they are!

At the metering stage the Zones are - according to Adams - precisely one stop different in brightness value. This is completely divorced and separate from how you make them appear in the print.

Exposure measurement is one thing. Translating that to a print is a completely different part of the process.

Even though you might envision the end result before you even meter it, there is a sequence of steps to be gone through, and one of those steps presumes that your metered Zones are one stop apart. How you expose and develop those brightness values then determines the print Zones, which are not the same thing at all.

Let's get rid of Zones for a while and put it on an objective and scientific basis.

You meter a certain area (A) in a scene, that after passing through the lens aperture throws 0.1 lux onto the film surface. There is another area (B) of the scene that throws 0.2 lux onto the film surface, a 3rd area © that illuminates the film with 0.8 lux. Those areas (A) and (B) are 1 stop apart, while areas (B) and © are 2 stops apart. Short of adding extra light to, or shading an area, there's absolutely nothing you can do to change those brightness relationships. They are what they are, and all you can do is to measure them. And it's only after measuring them that you can decide how to process the film such that you get a suitable density difference between those areas. A density difference that when printed will give the desired density difference(s) in the print.

Of course the light meter works out for you the shutter speed needed to get those lux values at the right part of the film curve, and a chart or experience can then help you decide how to develop the film, but, I repeat, there is nothing you can do at the point of exposure to alter the brightness relationships between parts of the scene.

All you can do is measure those brightness values.

When put in those objective terms the procedure isn't easy to grasp. So what Adams was trying to do was to generally categorise some of those fixed subject brightness relationships and make them easier to visualise as print tones.

And all I'm arguing is that he categorised some of them unrealistically. Such that the claimed brightness differences aren't physically possible.

...so the "Definition of Zones" cannot be taken as a precise metering reference.

That's the whole point.

It's Adams stance that his (scene) Zone definitions do fall at precise one stop intervals.

While I claim that his definitions of Zone V and Zone VIII absolutely preclude a 3 stop difference between them.

Let's take a practical situation:

There is a given scene, e.g. a close portrait on a badly lit scene. Check the sketch below.

You start the metering process, and you get the readings as follow: Background at left, 3 EV, face 4 EV, background top at right 6 EV.

The scene is low in contrast, but you want to get the best printable negative.

You want to place the background on the Zone III (quite normal); so the face will fall in zone IV (still too dark), and the back brightest area in the Zone VI.

It is, one stop difference from Zone III to IV, and two stops difference between IV and VI. Right?

So we plan to proceed. According with Adams` Description of Zones,

-Zone III is right as a background, we want to start it dark but with a little texture. As Adams` description.

-Zone IV is definitely too dark for my taste, I'd like it at least on Zone V. Adams say caucasian faces are Zone VI.

-Zone VI is still too dark for a highlight, I want it in Zone VIII, as Adams say.

So separation is of eight steps or Zones, I`ll check my testing charts and I'll expose and process the film accordingly.

What does your argument say in this case?

While I claim that his definitions of Zone V and Zone VIII absolutely preclude a 3 stop difference between them.

Well, I haven`t measured the difference between a dark face (how dark?) and at fallen snow (damp or cold?), but I'd take it as approximate...

As Flounder said in Animal House,

Oh boy, is this great!

Here I was getting nostalgic about how calm, polite, and bloodless this site had become. :rolleyes:

While I claim that his definitions of Zone V and Zone VIII absolutely preclude a 3 stop difference between them.

In Artificial Light Photography (Book 5 of the original series) Adams provides several tables that show where Zones V and VIII fall relative to magnesium carbonate, which was his reference for the highest diffuse reflectance (96% reflectance, approx. zone 7.4). From these tables and the surrounding discussion it's pretty obvious that Adams was clear about the relationship of the exposure zones.

Hopefully, there should be a similar passage in the three-volume rewrite.

In Artificial Light Photography (Book 5 of the original series) Adams provides several tables that show where Zones V and VIII fall relative to magnesium carbonate, which was his reference for the highest diffuse reflectance (96% reflectance, approx. zone 7.4).

That's interesting information. I must try and find a copy of that document.

It also makes it even more strange that Adams should then proceed to describe such objects as white picket-fences, freshly fallen powder snow and suchlike as having a Zone 8 reflectance. When it's easily demonstrable and measurable that their reflectivity is close to 100% and therefore, as you say, reflect only about 2.5 stops more light than an 18% card.

From these tables and the surrounding discussion it's pretty obvious that Adams was clear about the relationship of the exposure zones.

Perhaps you could expand on that? Because to me it seems to show that he disregarded any photometric evidence and went ahead to declare a faulty (but convenient) one stop interval between Zones. Or at least between Zones 5 and 8.

... it seems to show that he disregarded any photometric evidence and went ahead to declare a faulty (but convenient) one stop interval between Zones. Or at least between Zones 5 and 8.

Are you saying that nothing is brighter than a piece of blank white paper?

(I believe, although I am not entirely sure, that the sticking point seems to be the description of Zone 8 as "textured white".)

Are you saying that nothing is brighter than a piece of blank white paper?

No, of course I'm not.

Specular reflections can obviously be a lot brighter.

What I'm taking issue with is Adams' insistence that inherently matt white objects (as per his Zone descriptions) reflect 8 times more light than an 18% grey card. They don't!

Thinking on this has me wondering why he just didn't work in stops to begin with. They were in use long before his appropriation of them as Zones.

How much easier to say that "matt white stuff is about 2.5 stops brighter than a grey card" and "generally you can't see any detail in shadows that are more than 4 stops darker than a grey card". This was, I'm sure, common knowledge to photographers long before Adams tried to formalise and (over) refine it. And in the process attempted to neatly categorise a haphazard world into convenient - and wrong! - pigeon-holes.

Zones are things you can change, assign to different brightness levels. I can decide that two stops over middle will be zone vii, or viii, or even iii. We have control over this.

Stops are stops.

That's why Adams needed and invented Zones, and didn't just use stops.

What I'm taking issue with is Adams' insistence that inherently matt white objects (as per his Zone descriptions) reflect 8 times more light than an 18% grey card. They don't!

That's what I was thinking the trouble spot was: the interpretation of the words that describe how something looks. The tables and related text I previously referenced make it abundantly clear that matte objects do not fall on Exposure Zone 8 in the Normal exposure case.

Thinking on this has me wondering why he just didn't work in stops to begin with. They were in use long before his appropriation of them as Zones.

I think I vaguely remember him commenting on that somewhere, but don't remember what or where. Imagine, though, how confusing a zone progression of II.VIII, IV, V.VI, VIII, XI,...,LXIV would be! At any rate, a fixed geometric relationship could apply only to exposure zones--it would not work with negative or print zones--so some type of abstraction is necessary.

This was, I'm sure, common knowledge to photographers long before Adams tried to formalise and (over) refine it. And in the process attempted to neatly categorise a haphazard world into convenient - and wrong! - pigeon-holes.

The conceptual errors I have seen in this thread are not Adams's.

As far as I know, in the early days Adams based the Zone System zones on the dial of the Weston meter that he used to use:

This meter consider the useful range of a normal subject in seven stops, so from textured white to textured black. The dial has eight marks, that is, seven blank areas.

The mark on the right says "O" (overexposure) and the one on the left says "U" (underexposure).

But for whatever reason, Adams used the marks as steps, rather than separating points. It seems that Minor White used to do the very same thing.

So they considered eight zones instead of seven stops. It could seem unscientific, maybe, but it is his system.

After that, he added two more zones, for black and white, without texture. Ten zones, from 0 to IX.

I understand that the original Zone System is a symmetrical black-to-white system, "texture-based" is the goal of the method. And it is important to know that Adams executed it in a practical and very personal way.

In "The Negative" (12th ed.), I can read on the description of Zone VIII (page 60): Whites with texture and delicate values; textured snow; highlights on Caucasian skin.

I cannot see where it doesn`t match the aim of the system and the origin of their proposal. It`plenty clear to me that snow "should" fall as a Zone VIII on the print, whatever the distance from the middle grey the meter say it is in stops.

Snow reflectance can vary somewhat widely, depending on several factors... even so, you may be right if we were talking about the Munsell`s scale. But we are talking about Adams Zone System...

On page 49, he says: We define a one stop exposure change as a change of one zone on the exposure scale, and the resulting gray in the print is considered one value higher or lower on the print.

Still plenty clear to me. So the useful range of seven zones (or eight), still apply...

Is actually the meter reading of a textured snow out of that range? Maybe, not sure. I think there are different types of snow, and different reflective characteristics, depending on the thickness and base. I'm a fan of backcountry skiing, so for sure I'll get the meter when the season rolls around... (Provided that the Covid and our beloved authorities allow it!!)

The mark on the right says "O" (overexposure)

And where is that "O" mark?

Only three stops above Zone V, that's where!

I can see that words alone aren't going to convince.

Here's a Kodak calibrated greyscale against an evenly-lit surface that I'd definitely call "Whites with texture and delicate values...". The definition of Zone VIII according to Adams (p. 60 of 'The Negative' - 6th printing 1984).

Exposure was ISO 400, 1/13th s @ f/2.8, according to an incident meter reading from centre frame.

Now the same, at the exposure indicated by a spot reading from the whitewashed wall above the greyscale. I.e. placing the wall on Zone V.

This clearly shows the subtle texture in the paint (crazing and brush strokes).

Here's the same with exposure compensation of + 2.33 stops applied to the camera - i.e. placing the white wall at Zone VII + 1/3rd.

The camera indicated a shutter speed of 1/10th sec.

I've also superimposed part of the greyscale from the 'Zone V' exposure to prove that there is a genuine 2.33 stops difference between the exposures.

Each division on the Kodak greyscale is a density step of 0.1, which equates to a 1/3rd stop exposure step. So step 7 = 2.33 stops.

Now let's try to place the wall on Adams' Zone VIII with a + 3 stop compensation.

Whoa!

Where have all our "texture and delicate values" gone?

Blown out, that's where.

So much for 3 whole stops between Zone V (=18% reflectance) and Adams' description of Zone VIII, plus his insistence that each Zone is exactly a stop change in exposure.

This is easier to see in a histogram, where the white wall endstops the right-hand side of the graph.

OK. It's only half-a-stop, and you could get away with that in B&W film. Not so with a digital JPEG, where that extra third to half a stop exposure is critical, and will blow away that delicate detail needed in near-whites.

So, if the Zone system is to stay relevant in this digital age, then its Zones need re-defining.

Or we can simply work in good 'ol f-stops and chuck the pretentious Roman numerals away for good. Since adding the Latin for one-third or one-half a Zone would make an over-complicated system even more unwieldy.

FWIW. The 'M' step (0.7D) on Kodak's greyscale above actually represents a reflectance of close to 20%. A true 18% reflectance would have a density of 0.745. So there's a discrepancy of about 1/7th of a stop. The camera also only indicates exposure times to the nearest 1/3rd stop, even if the exposure time is given more precisely - if those things worry anyone.

It still is worth pointing out, i see, that Zones are what you want how parts of the scene in front of you appear in print.

Measure an x stop difference in subject brightness, apply compression (usually) or expansion as necessary to get what you 'previsualised', and that x stop difference is not an x zone difference. That is, unless you want it to be.

Zones are described in terms of what printing paper can render, and how it does that. Not in terms of subject luminance differences. The Zone System is about bending the latter to match the former, in a controlled way. The result of that control over differences in stops are Zones. Zones are not stops.

Can we use zones when the output medium no longer is an emulsion on paper? Of course we can. And then still zones are not stops. Zones are how we control the apperance of dark and light bits and everything in between. How we tame those blinking bits on our editor screens. Not the measured luminance values of the parts in the scene that lead to those blinking bits.

To re-quote Ansel Adams - "We define a one stop exposure change as a change of one zone on the exposure scale, "

Zone 7 is a two stop exposure change over zone 5. If one wants to expand a difference after the exposure has been captured, then one give increased development to move that zone 7 to zone 8.

I think people are arguing over printed zones rather than exposure capture zones. The zone system starts with the exposure capture. (a one stop exposure change as a change of one zone on the exposure scale,) Modifications in development and printing come later.

That's not quite correct: modifications start at the previsualisation stage. The target is the Zone, in print. The aim of the exercise is to measure and modify such that whatever difference in exposure values there may be, these differences end up as the difference (and placement) in zones that we are after.

Yes, you start with differences in exposure values, in stops, that on an ideal film and ditto paper (i.e. straight line, no shoulder and such) also are rendered as one stop differences. Then stops (both in the scene and at the print stage) and zones are identical. In real life all film compresses the differences, and unevenly too. And those compressed differences are expanded again (though not as much), unevenly again, when printing. A one-on-one relation between stops in the scene and zones in the print is impossible to achieve, and rarely wanted.

I think people are arguing over printed zones rather than exposure capture zones.

The descriptions of the exposure zones are still being conflated with those of the print values, it seems to me.

The descriptions are essentially the same up until about Zone VI, but because the brighter tones (exposure values greater than ~7.5) must be compressed to make them fit onto the paper's tonal scale, the descriptions deviate for Zones VII and up. Thus, Zone VII (paper white in the scene) is described as "light gray" in the print, and Zone VIII (semi-specular reflections) as white "with texture and delicate values" in the print. (Compression also applies to the darker tones, but for some reason the dark tones are not being disputed in this thread.)

It can be readily seen, in rodeo_joe's correctly exposed example, how Patches 1 and A (Exposure Zones 7 and 7.3) are displayed as light grays compared to PNet's white background.

Adams could have chosen to just simply truncate the tonal scale at a zone value of 7.5, like was done with the digital scale, but he designed the model to include semi-specular reflections (VIII), specular reflections (IX), and light sources within the image (X).

I cannot believe I'm writing this with my poor english... please be indulgent! :D

A definition is "something, typically expressed in words, that attaches a meaning to a word or group of words... " (Wikipedia). So IMHO, the aim of Adams` definition is not to make an obvious scientific statement, but to make an inseparable relationship between two facts, the metering (range) of a scene and the way this scene "should" look on the printing paper.

I see some abstraction in Adams` definition: "We define a one stop exposure change as a change of one zone on the exposure scale, and the resulting gray in the print is considered one value higher or lower on the print", we cannot take some words apart just because all are part of the definition.

Let`s analyze Adams`words:

-We define a one stop exposure change,.. he is giving the basis or starting point of his idea, the action of subject measuriement.

-... as a change of one zone on the exposure scale,... looks pretty obvious, but may be not... as explained in the post #119, one mark in the meter is not related to the measuring (although it could seem obvious) but to the idea of print density (the abstraction). In the same way we cannot explain historical facts from a current point of view, to know how they used to work could help to understand the real sense of his statement. Cannot remember if it was Adams or another who used to literally stick some gray shades on the meter for that reason. I think many people have their meters this way, and some print homemade dials as well.

-... and the resulting gray in the print... so there is a conjunctive fact/result direct relationship or correspondence between that exposure scale mark and the print density.

-... is considered one value higher or lower on the print. to clarify the idea of working in full steps (not f stops), which will be called "values", and will be the equivalent to that stops on the (real) scene.

Agree, in a "normal" range scene, three stops above the Zone V doesn't match the print Zone description (please notice that I use that "abstraction", I mix the purely objective meter data with the somewhat subjective "Zone value" idea) The question is, should it?

So I personally think that the definition is one way only, it cannot be taken in the opposite direction. One Zone value separation on the print don't necessarily have to be one f stop difference in the scene. And if so, it'd be contrary to the aim of the method, so it wouldn`t make sense.

So, if the Zone system is to stay relevant in this digital age, then its Zones need re-defining.

Agree, it may be that the (film) Zones description needs to be adapted to other materials ... for example, if you can get much more shadow detail using a digital camera with the same exposure, the game changes... It will depend on the usable latitude range of each material.

But I wonder if it'd be practical anymore... to me, the charm of the Zone System is attached to film, specially on a LF camera.

On digital, the histogram is the only thing I need. Maybe any kind of custom adjustment on it could be perfect.

If anyone still interested, looks like St. Ansel wrote his own answer in the introduction of "The Print" (1982). I read:

"... I wish to dispel here any thought that my approach is rigid and inflexible. I cannot repeat this too often! I have found that many students read descriptions of procedures in a rather strict way, and are then consumed with the effort to produce exact relationships between subject luminance values, densities and print values. No matter what he does the photographer cannot violate the principles of densitometry, but densitometry is a tough discipline and will tolerate a good amount of bending without breaking!"