Zone system mathematically inconsistent

Bill Burk said:

There’s cottage tier as well! Like Jason Lane dry plates.

alanrockwood I hope you feel differently now that what you thought was impossible about Zone System is OK.

Flaws, sure. Like it doesn’t address flare. I think it’s wasteful to shoot extensive film tests following Zone System procedure just to avoid buying a seven dollar step wedge.

But fundamentally it is OK.

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Not really. Physics hasn't changed and still requires diffuse reflectors to reflect no more than 100% of the light that falls on it, so if one takes 18% refectance as zone 5 then zone 8 (144% relfectance) is a physical impossibility for any object that is a diffuse reflector. I am pretty sure that the verbal description of zone 8 implies it is a diffuse reflector. For example, from a physical perspective snow is considered to be a diffuse reflector, so zone 8 is a physical impossibility unless one decides to change some of the definitions in the zone system.

As I mentioned in other posts, if specular reflection is present then the apparent reflectance can exceed that of a diffuse reflector. Actually, the reflectance is still limited to be less than 100%, but a perfect specular reflector doesn't scatter the light, so under a concentrated light source its apparent reflectance (when compared to a diffuse reflector) can exceed 100% under certain conditions, i.e. at certain angles with respect to the object's surface, the light source, and the light meter.

alanrockwood,

Right you are. If you can only get 5 stops from black to white, how can you describe normal as Zone V to Zone VIII and Zone V to Zone II for a spread of 6 stops?

Since you're right I'm not going to prove you wrong with this... It's just going to illustrate the issue in some solid terms we can agree on.

I'd like to refer you to the specifications of the 37-step reflection guide R3705

http://www.stouffer.net/R3705spec.htm

I enjoy this web page because it gives clear cross-references between percent and density - as it relates to a reflected light target. And it's a very easy trick to count f/stops of exposure in terms of density rather than percent... it's simply .30 density.

Now 18% is commonly called 0.74 density, and while this chart doesn't have an 18% patch it does have an 0.75 patch which is 17.78%

We can take that as equivalent to 18% for our illustration. Double that to 36% and then again to 72% and you are wondering how the heck you can get the next double in to 144%

On the Stouffer reflected light target you can see that from 18% you can go up by subtracting 0.3 from 0.75 = 0.45 = 35.48% so far so good.

Next doubling you subtract 0.3 again and get 0.45 to 0.15 = 70.79% still on track to agreeing with your illustration. Now you want to go up another .30 and there's only .15 left, and you can't even realistically go up any more.

Yes I see the issue you raise. It would have been much more sensible to pick a darker middle tone to key off of, say 0.90 or 12.59% which would give you full 3 stops to white. Too bad they didn't do that.

I see that also makes my tmxaim.jpg an impossible graph as well. I've somehow managed to draw 18% to 90.7% spanning 0.84 LogE (where 0.75 would be justified).
The mysterious 0.09 is not a sign that I have done the impossible. It is likely because different parts of the same roll of 35mm film can get different development. The part of the film where my frame 12 test was shot may have received better agitation than the part of the film where the sensitometry exposure was taken.

So in the same plane of a gray card held in open light and given Zone V exposure, the whitest white paper in the same light can only get 2 stops and a third greater exposure.

I tried to get Stouffer to make a grayscale with Zones on it and I suggested that it have Zone III, Zone IV, Zone V, Zone VI and Zone VII only. Because that's practically all you can represent in a flat target in same light. They didn't want to do that but I still think it's a good idea. We could put Zone V at .75

So a reasonable set which keeps 18% as traditional reference gray can be like this...
Zone III 1.35, Zone IV 1.05, Zone V .75, Zone VI .45 and Zone VII .15

Cheers,
Bill

Over-analyzing any technique can render it much less valuable. Photographers have found the zone system useful. It's better to learn how to use it, right or not, than to quibble about whether it is perfect or not. Let the engineers and scientists argue about it. That keeps them from even more wasteful activities.

Another illustration of Zone VIII working in practice though impossible mathematically is that you may meter on the gray card to determine Zone V exposure and open up three stops.

That does put 144% exposure on the film. Then when you go to the darkroom you find that it shows faint detail. So even though it is more than you would have from anything white in the Zone V based exposure scene, a white object that has the equivalent of 144% will show up nicely in a normal print. Even as you approach 288% for that matter - those white clouds in the background which are in full sunlight (while your graycard might be in hazy sun). They approach being blocked but because you implemented Zone System they are just barely blocking in the print.

If you develop the film much longer, my favorite mistake amount for example... 35% longer, those clouds will be difficult to print. And “that” kind of control (holding highlights) is one of the chief benefits of the Zone System

Jim Jones said:

Over-analyzing any technique can render it much less valuable. Photographers have found the zone system useful. It's better to learn how to use it, right or not, than to quibble about whether it is perfect or not. Let the engineers and scientists argue about it. That keeps them from even more wasteful activities.

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Ah...but scientists and engineers can be photographers, too, and even be artists! And quibbling the details is part of their art. Listening in can be entertaining and educational!

p.s. Kodak gray cards have a white side (to use in dim light) and Kodak says divide the film speed by 5 when using the white side.
This is 2 1/3 stops - pretty much same as our discussion. You can get just a bit over Zone VII

Bill Burk said:

Another illustration of Zone VIII working in practice though impossible mathematically is that you may meter on the gray card to determine Zone V exposure and open up three stops.

That does put 144% exposure on the film. Then when you go to the darkroom you find that it shows faint detail. So even though it is more than you would have from anything white in the Zone V based exposure scene, a white object that has the equivalent of 144% will show up nicely in a normal print. Even as you approach 288% for that matter - those white clouds in the background which are in full sunlight (while your graycard might be in hazy sun). They approach being blocked but because you implemented Zone System they are just barely blocking in the print.

If you develop the film much longer, my favorite mistake amount for example... 35% longer, those clouds will be difficult to print. And “that” kind of control (holding highlights) is one of the chief benefits of the Zone System

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From a practical standpoint it seems that we photographers have but two primary controls in film development assuming a standard method of agitation, those being effective film speed and development time.
Using Zone I and Zone VIII density values from Ansel Adams "The Negative" to quantify EI and development time for our individual developer - film - agitation methods to achieve an "easily printed negative"
seems to be a good goal. With those two controls, metering a grey card for exposure and letting shadow areas and highlight areas fall where they may works great for me. In outdoor scenes I do love fluffy clouds
like everyone else and do spot meter the clouds to see if they are more than three stops above my grey card exposure. Given what is important I may or may not adjust.

I do appreciate the knowledge and expertise of everyone that has posted to this thread, but from a practical standpoint, is there anything else that would factor in to a negative with a nice range of values other than
EI and development time that would be illuminated by this discussion ? I do understand further control by time to achieve expansion and contraction and consider that part of development time, not a separate method of available control.

bascom49 said:

From a practical standpoint it seems that we photographers have but two primary controls in film development assuming a standard method of agitation, those being effective film speed and development time...

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We fortunately do have more control than that. Since we have little control over a particular film's effective speed, perhaps exposure (relative to effective film speed) would be a better, and classical, way to look at it. Exposure is an important control mechanism. The use of the reciprosity failure of a film are, for example, can be an important control in making a negative that one wants to print with.

Averaging readings work for average scenes printed using average means. I do not know if I am above or below average, but I don't see average much!

Vaughn said:

We fortunately do have more control than that. Since we have little control over a particular film's effective speed, perhaps exposure (relative to effective film speed) would be a better, and classical, way to look at it. Exposure is an important control mechanism. The use of the reciprosity failure of a film are, for example, can be an important control in making a negative that one wants to print with.

Averaging readings work for average scenes printed using average means. I do not know if I am above or below average, but I don't see average much!

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I whole heartedly agree. There are certainly many different interpretations for any given scene as to how one may choose to meter and decide on exposure.
Establishing and deciding on an EI for the intended film - developer - agitation method is a part of that, and then in the darkroom development time is the next part.
So understanding and deciding on personal EI on one end and development time on the other end as per Ansel Adams "The Negative" with personal decisions as to exposure and metering to make the image in the middle of the two,
what does an in depth understanding of sensitometry and film curve characteristics such as discussed in this thread bring to our work as creatives and photographers ?
From those that are much more knowledgable of film and it's characteristics as determined from in depth testing, technical discussions, etc. are there any definitive facts, comments, or understanding that could be shared with the rest of us
that would help in a meaningful way ?

Never tested for EI...never felt the need to nor wanted to spend time doing so. So I guess I do not consider it personally important...box speed has been fine as a starting point. From there it is a matter of exploring a particular type of light with a camera/lens/film combo and finding what will best produce a print that shows that light as I experienced it. I utilize my limited knowledge of sensitometry and film (curve) characteristics as a creative photographer/artist to find ways to tweak my materials and process in the direction of producing art.

It is good to have a reason to photograph. More important to me than testing, which I do through the age-old method of trial and error. After a few decades of mistakes and occasional successes, I can honestly say I will have more mistakes and successes in the future. And probably at a similar ratio.

When I was at Cape Canaveral (CCMTA), every film contractor such as PAA and RCA, tested every film product for speed and quality by selecting one box or more and removing a sheet or roll and examining for coating quality and adherence to ASA speed. They NEVER found a deviation in Kodak, GAF or Dupont products. I was one of several people trying to dissuade them from this as we considered it a waste of taxpayer money. However, the practice continued, and did so even as I was leaving when my assignment ended.

This goes to the use of ISO and the Zone System. ISO was verified by the companies so no one would have to do work to be assured of good pictures.

PE

bascom49 said:

Finer, Finer Points:
8) Agonize incessantly over logs, graphs and sensitometry
9) Spend all of your time testing.
10) Spend the rest or your time graphing and curve plotting.
11) Spend no time actually being a photographer.
12) Gain perspective by reading works by Kurt Godel, go back to steps 1 thru 5 and return to photographic happiness again.

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people learn differently;some need just to read about it;others need to try and do it before it's understood; and some need to reaqlly dig into the underlying theory to fully understand;important is to find your best way of learning and then to apply the newly learned into your work to improve results.

RalphLambrecht said:

people learn differently;some need just to read about it;others need to try and do it before it's understood; and some need to reaqlly dig into the underlying theory to fully understand;important is to find your best way of learning and then to apply the newly learned into your work to improve results.

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Well Said

I always include a test when I develop film. If not every run, at lest every few.

Fresh film is good and does not need to be tested to prove it is good.

But I am about to open a bulk roll of film that expired over thirty years ago. Don’t you think that ought to be tested?

Vaughn said:

Never tested for EI...never felt the need to nor wanted to spend time doing so. So I guess I do not consider it personally important...box speed has been fine as a starting point. From there it is a matter of exploring a particular type of light with a camera/lens/film combo and finding what will best produce a print that shows that light as I experienced it. I utilize my limited knowledge of sensitometry and film (curve) characteristics as a creative photographer/artist to find ways to tweak my materials and process in the direction of producing art.

It is good to have a reason to photograph. More important to me than testing, which I do through the age-old method of trial and error. After a few decades of mistakes and occasional successes, I can honestly say I will have more mistakes and successes in the future. And probably at a similar ratio.

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Photo Engineer said:

When I was at Cape Canaveral (CCMTA), every film contractor such as PAA and RCA, tested every film product for speed and quality by selecting one box or more and removing a sheet or roll and examining for coating quality and adherence to ASA speed. They NEVER found a deviation in Kodak, GAF or Dupont products. I was one of several people trying to dissuade them from this as we considered it a waste of taxpayer money. However, the practice continued, and did so even as I was leaving when my assignment ended.

This goes to the use of ISO and the Zone System. ISO was verified by the companies so no one would have to do work to be assured of good pictures.

PE

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Box speed
Box speed
Box speed


I use a spot meter, choose an area, meter that area, set that reading in the proper Zone, take the Zone V reading and set the camera, if necessary adjust for the filter factor. Then I use replenished XTOL in the Jobo processor and the exposure and negatives are spot on.

There is no reason to use an EI. Whenever I have worked with someone who needed an EI, we found that the light meter or camera was out of calibration and-or the person had the sky in the light reading.

With my newer bodies like the Minolta 9, (for that all of the Minolta AF bodies) box speed is pretty much dead on with Tmax films, when I use Ultrafine for Foma I do need to test for a working E.I. I use 3 developers, D76, DDX, and MCM 100, in the past I also used Edwal 12. With older mechanical bodies, there is much more variance as the shutters are aging. I have 3 M42 bodies, a Spotmatic, and 2 Chinon the EI ranges 3 stops. Yes that means the camera is out of calibration, keeping them in tolerance, too much trouble and expense to send to bodies out for maintenance.

Photo Engineer said:

When I was at Cape Canaveral (CCMTA), every film contractor such as PAA and RCA, tested every film product for speed and quality by selecting one box or more and removing a sheet or roll and examining for coating quality and adherence to ASA speed. They NEVER found a deviation in Kodak, GAF or Dupont products. I was one of several people trying to dissuade them from this as we considered it a waste of taxpayer money. However, the practice continued, and did so even as I was leaving when my assignment ended.

This goes to the use of ISO and the Zone System. ISO was verified by the companies so no one would have to do work to be assured of good pictures.

PE

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Quite right but you of course did not test todays films at the Cape! Ilford Delta 3200 was not
avaible to that time!
I made a test with Rollei R3 (it cost me more than 20 rolls - but they gave me 80rolls 120 film R3)
I can't reach ISO 6400 ! MY FINAL CONCLUSION WAS ISO 400!

with regards

Sirius Glass said:

Box speed
Box speed
Box speed


I use a spot meter, choose an area, meter that area, set that reading in the proper Zone, take the Zone V reading and set the camera, if necessary adjust for the filter factor. Then I use replenished XTOL in the Jobo processor and the exposure and negatives are spot on.

There is no reason to use an EI. Whenever I have worked with someone who needed an EI, we found that the light meter or camera was out of calibration and-or the person had the sky in the light reading.

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Yes that seams to be quite clear = the use of a different E.I. (in concern to box speed) seams
to indicate a failure in min. one section of the complete chain of workflow (messurement/exposure/development/enlarging) !
But to use a different E.I. in concern of intention (for example E.I = ISO 800 with Tmax 400) is
a total different story! Here we have it (missunderstanding from other threat)!
So we were B O T H right (you from your point/ me from my point) !

with regards

I doubt if US government agencies are using Ilford film.

They did not when I was there.

PE

Photo Engineer said:

I doubt if US government agencies are using Ilford film.

They did not when I was there.

PE

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Yes ..........that is a good point PE! DT would give order to avoid Fuji - just if he would know anything about films!

with regards

PS : Hope they will not read this threat and come up to test New Tmax 3200!

According to Jack Holm in Exposure Speed Relations and Tone Reproduction, “Two significant assumptions which are often neglected in exposure determination concern the scene range and mean reflectance. They are as follows:

That the luminance range of a statistically average scene is 160:1 (log range 2.20), and the resulting exposure range on the image capture medium is 80:1 (log range 1.90), corresponding to a camera flare actor of 2.

That the mean log luminance of a statistically average scene is approximately 0.95 log units below the highlight log luminance (edge of detail in white) and 1.25 log units above the shadow log luminance (edge of detail in black), and that this mean luminance is assumed to be the luminance metered, directly or indirectly for exposure determination. These values result in the mean luminance correlating with a Lambertian scene reflectance of 12% for 100% highlight reflactance…Flare results in the mean log exposure being halfway between the highlight and shadow log exposures.” Subtract the 0.30 value for flare from 1.25 and you get shadow falling 0.95 below metered camera exposure and highlight falling 0.95 above.

Attached is a numerical breakdown that comes close to the conditions outlined by Holm.

Some what off topic, I gave a quick read to Phil Davis Beyond the Zone System years ago, don't recall much about the math behind his method, how does it compare to the math in AA's system?

Photo Engineer said:

I doubt if US government agencies are using Ilford film.

They did not when I was there.

PE

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Don't think any US Governmental Agency is using much if any film, other than for archive. When I was shooting for the Air Force we used Kodak, GAF, (which we all hated) and a mystery film rated at 200, made in USA without a trademark. It was rather good black and white, I assumed it was Dupont made to order for the DOD, and I recall seeing bulk rolls of 3M E6. The recon guys had their own stock.

Stephen Benskin said:

According to Jack Holm in Exposure Speed Relations and Tone Reproduction, “Two significant assumptions which are often neglected in exposure determination concern the scene range and mean reflectance. They are as follows:

That the luminance range of a statistically average scene is 160:1 (log range 2.2), and the resulting exposure range on the image capture medium is 80:1 (log range 1.90), corresponding to a camera flare actor of 2.

That the mean log luminance of a statistically average scene is approximately 0.95 log units below the highlight log luminance (edge of detail in white) and 1.25 log units above the shadow log luminance (edge of detail in black), and that this mean luminance is assumed to be the luminance metered, directly or indirectly for exposure determination. These values result in the mean luminance correlating with a Lambertian scene reflectance of 12% for 100% highlight reflactance…Flare results in the mean log exposure being halfway between the highlight and shadow log exposures.” Subtract the 0.30 value for flare from 1.25 and you get shadow falling 0.95 below metered camera exposure and highlight falling 0.95 above.

Attached is a numerical breakdown that comes close to the conditions outlined by Holm.

View attachment 222484

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That is one of the most informative discussions I have ever read on this topic. I will have to get a copy of the paper you referenced.

alanrockwood said:

That is one of the most informative discussions I have ever read on this topic. I will have to get a copy of the paper you referenced.

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It's available on the link Bill Burk supplies. Along with the Holm's paper are many for the principle papers on exposure and film speed.

http://beefalobill.com/benskin/content