Zone system mathematically inconsistent

StepheKoontz · Apr 16, 2019

KN4SMF said:
The fatal flaw in the zone system is that it is base on an exposure meter with no equality of color sensitivity. No meter does.

Which is why I use an incidence meter. I look at the scene and decide what parts need to be "metered right", look closeby for similar light, meter the light falling on the scene and shoot. Trying to measure reflected light is not very accurate IMHO. I mostly shoot roll film but even with sheet film, I push/pull development for contrast as needed. I find modern B&W film to be forgiving enough for this to work fine and I don't get a headache while I am out shooting

Andrew O'Neill · Apr 16, 2019

Even though it is somewhat flawed, it still provides me with a multitude of ways to expose/develop a piece of film.

Vaughn · Apr 16, 2019

jim10219 said:
Yeah, it's easy to believe the hype on this one. It gets passed off as a super accurate system. And for those of us who are used to the averaging meters in our old cameras and maybe an incident reading, it is. But in reality its more practical than scientific in it's approach.

When I mess up on an exposure, I certainly do not blame science!

Consideration needs to be factored in for the process to be used. My negatives are exposed and processed for a much different range of density than those for silver gelatin printing. A normal to large scene brightness range is exposed for the deepest shadow I want detail -- Zone II or III, depending on how I am feeling, the film I am using (reciprocity failure), etc. Then I about double the 'normal' development -- I am not going to scrunch up any light values! I have melded this with the way I make, sensitize, expose, and process the material for carbon printing to create prints that speak about the light in my voice. Certainly not cookbook exposure and processing, but the Zone System is a way to understand what is going on.

While I do not worship Saint Ansel Adams, I am known to chant "One ansel adams, two ansel adams, three ansel adams..." for minutes at a time to pacify the wind gods of the redwoods.

faberryman · Apr 16, 2019

alanrockwood said:
You first do some background work, i.e. testing to set up your film/developer combination for your preferred gamma. That gives you a recommended exposure index for that film/developer combination. When you are going to shoot a photo (which could be years after you have set up your preferred gamma, hence your effective film speed) you set your meter to the recommended "iso" for that film/developer combination and meter the main subject of interest in the photo.

There is nothing sacred about a gamma of 0.82. It is simply the value I got when testing this film developer combination.

cowanw · Apr 16, 2019

Andrew O'Neill said:
Even though it is somewhat flawed, it still provides me with a multitude of ways to expose/develop a piece of film.

And here I was kind of hoping for one.

Arklatexian · Apr 16, 2019

alanrockwood said:
I don't know why I didn't realize this before, but I think I finally understand part of the reason why I have been having trouble understanding the finer points of the zone system, at least in a quantitative sense. The reason is that it makes no sense in a quantitative sense, assuming we discuss it in terms of powers of two. By this I mean that if we assume that each step in the zone system corresponds to a power of two in exposure then the system is mathematically inconsistent.

Let me explain. Let us assume, for example, that an object that of 100% reflectance is placed in zone 9. Then 50% reflectance (corresponding to a one f-stop difference) would be in zone 8, 25% reflectance would be in zone 7, 12.5% reflectance would be in zone 6, and 6.25% reflectance would be in zone 5. Here is the inconsistency. Zone 5 is commonly said to correspond to 18% reflectance, but the 6.25% number we get by counting down from zone 9 is only about a third of 18%. Therefore, the zone system is not mathematically consistent.

My conclusion is that, while the zone system may be qualitatively/conceptually useful, it is not quantitatively correct.

Isn't that true of most art forms? Have you ever heard of water-colorists using "x amount of cadmium-yellow" to "x amount of red" to "x amount of water"? That would be the equivalent of putting them into a "straight-jacket". Doesn't the "zone system" require a certain amount of judgement by the photographer? Possibly more "judgement" than I possess.........Regards!

vivizen · Apr 16, 2019

So my understanding of how the conventional (i.e Ansel) zone system is defined is as follows.

Typical objects have a reflectivity range somewhere between 4% and 90%. This range, expressed in EV stops is:
log_2 (0.9/0.04) = 4.5
i.e. 4.5 stops of dynamic range. (here log_2 means logarithm to base 2)

"Zone V" is defined as the logarithmic middle of this 4.5 stop dynamic range, i.e.
0.9/2^(4.5/2) = 0.9/2^2.25 = 0.9/4.76 = 0.189
In other words, "Zone V" is 18.9% reflectivity.

So everything does make quantitative sense.

Rudolf Karachun · Apr 16, 2019

https://www.google.com/url?sa=t&sou...FjAaegQIBBAB&usg=AOvVaw0thS53aWeLz6I4GbalGlwj

May this link help.

Bill Burk · Apr 17, 2019

alanrockwood,

In one of your posts you say you want to capture the widest range of exposure on film.

To do that you may use a long toe film and put a lot of the scene’s lower range of exposures on the toe. You will then span a wider exposure range, while still keeping the same development and highlight densities (keeping your 0.8 gamma.) You scrunch (compress) the less-important shadows. They contain detail but it’s low contrast detail in the shadows. All the high contrast is there to print in the mid and upper-mid tones.

If I overexpose the exact same picture to put it on the straight line, then it will have a greater density range and I must use a lower contrast paper to get similar shadow appearance on the print (assuming I put the highlights in the same tone). In other words I wreck the tonality. Oh I could dodge the shadows (actually that’s my usual solution). But less exposure on a long toe film is important to enough people... it’s so important that Kodak has to keep making Tri-X

RalphLambrecht · Apr 17, 2019

alanrockwood said:
I don't know why I didn't realize this before, but I think I finally understand part of the reason why I have been having trouble understanding the finer points of the zone system, at least in a quantitative sense. The reason is that it makes no sense in a quantitative sense, assuming we discuss it in terms of powers of two. By this I mean that if we assume that each step in the zone system corresponds to a power of two in exposure then the system is mathematically inconsistent.

Let me explain. Let us assume, for example, that an object that of 100% reflectance is placed in zone 9. Then 50% reflectance (corresponding to a one f-stop difference) would be in zone 8, 25% reflectance would be in zone 7, 12.5% reflectance would be in zone 6, and 6.25% reflectance would be in zone 5. Here is the inconsistency. Zone 5 is commonly said to correspond to 18% reflectance, but the 6.25% number we get by counting down from zone 9 is only about a third of 18%. Therefore, the zone system is not mathematically consistent.

My conclusion is that, while the zone system may be qualitatively/conceptually useful, it is not quantitatively correct.

the Zone System is an artistic not a mathematical concept.

bernard_L · Apr 17, 2019

alanrockwood said:
Let me explain. Let us assume, for example, that an object that of 100% reflectance is placed in zone 9.

When I first sighted this thread I had decided to stay away (oh no, not again!) . Yet...
You start by assuming something about a system "X" (or "Z") and when you encounter an inconsistency you blame it on system "X". Did it occur to you that your initial assumption might be flawed? Like, assuming that photography is about picturing a reflective object (R<=100%) under uniform lighting?
The zone system really becomes useful when one has to make decisions to render a sunlight-and-shadow scene, where more comes into play than reflectance.
Put it another way, your arithmetic simply shows that white paper is only 2.5 zones above the 18% gray card (or 3 zones above the 12% gray, whatever, that is not the topic, pleeez), and that when photographing a reflective object under uniform lighting, there is no problem to fit the scene dynamic range into the film's logE range. And no need for ZS.

CMoore · Apr 17, 2019

Not just photography, but any hobby forum i have ever belonged to..........some of the discussions make me wonder why people are even involved, because "nothing ever" seems to be any fun for them.

While Keith Richards and Jimi Hendrix were doing their thing, and having the time of their lives, a bunch of musicians on a Forum were pointing pout that A-440 was the complete wrong approach for tuning an instrument.

I am just a beginner at photography, just a hack Street Photographer, and probably always will be...but i Love It.
Knowing the basics of "The Zone System" has helped me quite a bit.
So let me ask, is the zone system not working for anybody...is the practice of it screwing up your pictures.?

CMoore · Apr 17, 2019

RalphLambrecht said:
the Zone System is an artistic not a mathematical concept.

May the Saints be praised.....

Maris · Apr 17, 2019

I think the Zone System extends beyond grey-scale rendering of surface reflectances under a given lighting intensity. The Zone System attempts an approach to exposure and development that can cope with subject matter that includes dark things in the shade and white things in full sunlight. The luminance range here is way beyond nominal reflectances.

Photo Engineer · Apr 17, 2019

The Great Photographers, who used the Zone System, got great pictures because they were Great Photographers, not because they used the Zone System.

That was an adjunct aid for them to help pass on information to the rest of us perhaps.

PE

Peter Schrager · Apr 17, 2019

Photo Engineer said:
The Great Photographers, who used the Zone System, got great pictures because they were Great Photographers, not because they used the Zone System.

That was an adjunct aid for them to help pass on information to the rest of us perhaps.

PE

It just gets me past making too many pictures
I'm after results not sensitometery

Peter Schrager · Apr 17, 2019

That did come out correct..just gets me past thinking too much ...results people

Sirius Glass · Apr 17, 2019

Photo Engineer said:
The Great Photographers, who used the Zone System, got great pictures because they were Great Photographers, not because they used the Zone System.

That was an adjunct aid for them to help pass on information to the rest of us perhaps.

PE

It helps me get a particular area in the Zone I want and no more. The composition, developing and printing are up to me.

removed account4 · Apr 18, 2019

OP
Good luck figuring it all out!
I just wing it with Sunny16 and don’t sweat the heady technical math science stuffs. Thankfully I set the bar really low and have fun.

That said I think the difference between the 2 percentages you discovered is called “wiggle room” in the industry

nmp · Apr 18, 2019

bernard_L said:
When I first sighted this thread I had decided to stay away (oh no, not again!) . Yet...
You start by assuming something about a system "X" (or "Z") and when you encounter an inconsistency you blame it on system "X". Did it occur to you that your initial assumption might be flawed? Like, assuming that photography is about picturing a reflective object (R<=100%) under uniform lighting?
The zone system really becomes useful when one has to make decisions to render a sunlight-and-shadow scene, where more comes into play than reflectance.
Put it another way, your arithmetic simply shows that white paper is only 2.5 zones above the 18% gray card (or 3 zones above the 12% gray, whatever, that is not the topic, pleeez), and that when photographing a reflective object under uniform lighting, there is no problem to fit the scene dynamic range into the film's logE range. And no need for ZS.

Who cares if the thread was started with a false premise, look how much fun it is to discuss it (or something else) anyway....

Photo Engineer · Apr 18, 2019

When I was young and able, and working on color paper and color negative film, I had to do all of this from scratch. That means doing sensitometry, densitometry and exposures in-camera and on-easel to verify the quality of my coatings. This was a painstaking job I and others at EK did for your benefit so that you did not have to do it. We did it using a 21 step scale for accuracy.

Now, all you have to do is center the exposure on the straight line, using the ISO on the box, and away you go. I know this because I helped design the product and assign the ISO value, so I know it works. I never do this fol-de-rol anymore. I just point and shoot and let the camera, set to the right ISO, do the job. It works. I know this from using it for the better part of a lifetime.

So, you can spend hours figuring things out, or you can have fun and shoot pictures. Try one at the ISO and then at -1/2 and +1/2 and that should do the trick.

PE

CMoore · Apr 18, 2019

Photo Engineer said:
So, you can spend hours figuring things out, or you can have fun and shoot pictures. Try one at the ISO and then at -1/2 and +1/2 and that should do the trick.

How do you know what to do with development time.?
If i had a box that a roll of 35mm came in i could look. Does the info on the inside of the box address development times when shooting at 100 or 400 for an ASA-200 roll of film.?
Thank You

Luckless · Apr 18, 2019

CMoore said:
How do you know what to do with development time.?
If i had a box that a roll of 35mm came in i could look. Does the info on the inside of the box address development times when shooting at 100 or 400 for an ASA-200 roll of film.?
Thank You

Use a standardized development time that's listed on your developer? [Or the spec sheet for the developer. Or from something like the Massive Dev Chart site?]

Photo Engineer · Apr 18, 2019

CMoore said:
How do you know what to do with development time.?
If i had a box that a roll of 35mm came in i could look. Does the info on the inside of the box address development times when shooting at 100 or 400 for an ASA-200 roll of film.?
Thank You

And that is the nice thing about negative film. It has a huge latitude if you expose normally in the center of the curve on the straight line portion. Normal development will give you about 1 stop on either side and so you normally (with mainstream films) don't have to adjust the development time and push or pull.

With 3rd tier films, they often achieve speed by higher contrast and there, you are out of luck!! With Ilford, Fuji and Kodak, you will not have to adjust development time.

However.... for those who prefer to adjust, I always suggest a test roll with their favorite film and running push and/or pull processes on the film before shooting with a given film.

I have run test with films from most major manufacturers and many small ones to verify this with a variety of films.

PE

Theo Sulphate · Apr 18, 2019

Photo Engineer said:
...
Now, all you have to do is center the exposure on the straight line, using the ISO on the box, and away you go. I know this because I helped design the product and assign the ISO value, so I know it works.

Was this before or after The Great ASA Change (*) of 1960?

(*) From Wikipedia:
" ... The ASA standard underwent a major revision in 1960 with ASA PH2.5-1960, when the method to determine film speed was refined and previously applied safety factors against under-exposure were abandoned, effectively doubling the nominal speed of many black-and-white negative films. ..."

Zone system mathematically inconsistent

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