N- and N+ Development Question

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N, N+1, N-1 etc is trying to compress zones VI and above. I don't know how other feel about what I'm gonna say, but I always process normally and use graded paper to adjust the contrast. I'm not absolutely sure, but I think the Zone system was used in the days of graded paper and adjusting the processing made the range of the negative closer to grade 2. The Zone system is valuable with previsualization. I always have an end goal of what paper I'm going to use and I process my film with the intention of printing on VC paper with grade 3.
 

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This is how I see silveror0's family of curves for HP5 Plus in HC110.

Using the Time-Contrast Index (CI) chart derived from silveror0's curve family... and using Stephen Benskin's figures for Grade 2 paper...

N+1 = 0.70 CI = 12 minutes
N = 0.58 CI = 9 minutes
N-1 = 0.50 CI = 7 1/2 minutes.

Notice the computations both ways arrive very closely at the same number of minutes. Very close to what silveror0 arrived at using traditional Zone System graphing analysis.

hp5plusfamily.jpg
 

Luis-F-S

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It is confusing because no one ever really knows what someone else is saying unless they are very detailed in saying what they actually mean. For example, according to Adams, N+1 leaves zone IV on zone IV, so using your interpretation then zone IV would become zone V. And since everyones interpreation is different, discussion about the zone system becomes a very big circle of confusion.
No its because the lower Zone densities are determined by exposure (ASA) not development. You can develop the hell out of Zones I - IV and the densities won't increase much compared to Zones VI thru VIII.
 
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It is an oversimplification to think that changing the degree of development just moves the highlights around. Yes, the low values remain roughly the same, but middle values can move a surprising amount. Just looking at a graph will help, but really seeing a grey tone on a piece of photographic paper tells the whole story of tone reproduction.

Just how much low and mid-tones change with expanded and contracted development is easily shown by making Zone Rulers (outlined in "The New Zone System Manual" by White, Zakia and Lorenz). I've done this for many film/development schemes and it is very enlightening. My take is that expansions move Zone V up the scale by quite a bit, and I take this into account when visualizing and placing those values. I know that Zone V for N+2 results in a print value that's closer to Zone VI on the "Normal" scale. Contractions tend to change the mid-tones less provided that adequate extra exposure is given to compensate for the loss of speed, but there are still significant differences in the scales. I couldn't visualize accurately without this information. I used to carry the Zone Rulers around with me in the field, now they are in my head.

Best,

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Because of simultaneous contrast and local adaptation, scales can be misleading. For instance, the eye will compress the lower tones. The matter of degree depends on the surrounding tones, which includes the tones in the scale / print and the area outside of the printed image.
 
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Jim Noel

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When people refer to N- and N+ I know they are either extending or shortening the development time but when they say N-1 or N+1 (what does the 1 mean) in terms of development. Does it mean 10% ?
N-1 indicates lowering Zone IX to VIII. With most film/developer combinations this requires about a 25% reduction in development time.
N+1 indicates raising Zone VII to Zone VIII which requires an increase of 40% in normal development time.
These percentages are not always exact, but generally they are very close.
 
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I'd also like to add that, before doing the tests, I check the shutter speeds for the lens used. I also have the habit of changing apertures in the "closing down" direction to eliminate the mechanical free-play from causing any error (no idea how much that error can be); this was suggested by AA - the geek of geeks - at a '66 workshop, so I just do it.

Adams in actuality wasn't very good at theory. The aims for NDR and Zone I are based on a misconception. Ever wonder why the LER for Grade 2 paper for a diffusion enlarger is 1.05 and Adams has a 1.15 - 1.25 for the NDR? Or how ZS film speed testing almost universally results in EIs 1/2 to one stop slower than the ISO speed?
 

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N-1 indicates lowering Zone IX to VIII. With most film/developer combinations this requires about a 25% reduction in development time.
N+1 indicates raising Zone VII to Zone VIII which requires an increase of 40% in normal development time.
These percentages are not always exact, but generally they are very close.

This is what I was alluding to earlier in this thread.
 

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This thread really has helped me a lot in thinking about the zone system and the characteristic curve. The characteristic curve is really a complete quantitative measure of film performance for a given development time. Changing development time really affects all parts of the curve, but it clearly is a proportional (not necessarily linear) effect: higher densities are affected more than lower densities.

The zone system tries to capture the whole curve and its dependence on development by focusing on a few points only. In particular it defines film speed as a fixed density above base and fog, irrespective of gamma or contrast index. However, the ISO film speed specifies a gamma of 0.62 and a density of 0.1 above base and fog. I think that this explains why most people using the zone system find an EI around 1/2 of the ISO speed, since the zone system aims for a lower contrast index than ISO does. Is this correct?

Furthermore, I can find a very similar result by using the time gamma curve which are supplied by the manufacturer and just pick the time for a somewhat lower gamma, effectively providing more shadow detail and better highlight control. If I am now willing to believe that most camera manufacturers as well as light meter producers roughly get their f-stops etc right ... Or is this heresy :wink:
 
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However his system did apparently work for him, as he seems to have had a measure of success with it. Dead Link RemovedDead Link RemovedDead Link Removed

The Zone System is based on tone reproduction theory. I'm not saying it doesn't work, but if you have a good grasp of sensitometry and tone reproduction theory, you will notice that his aim numbers are off. With the negative density range aim, the problem is the test uses a no flare situation (or minimal flare) and Adams is assuming the testing contains average flare. Average flare is 1 stop. Instead of finding the density range at 7 stops, flare reduces the 7 stops to 6 stops. His 1.15 - 1.30 NDR doesn't conform to the LER of a grade two paper, but the NDR at 6 stops does. Most Zone System users are unaware of this because it is extremely difficult to measure flare in a test and Adams never discussed how to determine the print LER.

LER and NDR chart a.jpg


A simple test is to calculate the average gradient from the Zone System numbers and those from tone reproduction theory.

LER / Log Subject Luminance Range - Flare

Zone System:
1.20 / 2.1 = 0.57

Tone Reproduction:
1.05 / 2.1- 0.30 = 0.58

The average gradients have the same value, therefore the results are the same; but the variables are different. Which one reflects the real world? Hint: Not the Zone System.

Speed Point - Metered Exposure Ratio - Flare Model - Zone markings A.jpg


As for film speed, the ISO speed is determined at a point 3 1/3 stops below the metered exposure point. ZS uses 4 stops below. Zone System methodology never changed and after the 1960 film speed standard there was a discrepancy between the two methods. That is why Zone System tests almost universally find the EI to be 1/2 to 1 stop below the ISO speed. In most cases it isn't because personal testing represents your equipment and processing.

Speed Point - Metered Exposure Ratio - Zone System apug.jpg


BTW, you mentioned that you use a lens shade to minimize flare. Because you contact the step tablet, camera flare will not affect the test.
 
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The zone system tries to capture the whole curve and its dependence on development by focusing on a few points only. In particular it defines film speed as a fixed density above base and fog, irrespective of gamma or contrast index. However, the ISO film speed specifies a gamma of 0.62 and a density of 0.1 above base and fog. I think that this explains why most people using the zone system find an EI around 1/2 of the ISO speed, since the zone system aims for a lower contrast index than ISO does. Is this correct?

That would make sense if the ISO film speed standard simply used a fixed speed point. The ISO contrast parameters are part of the Delta-X Criterion which has a good correlation with the Fractional Gradient method. With Delta-X and Fractional Gradient methods, film speed doesn't change very much with changes in development. The below table compares fixed density speeds with Delta-X speeds.

Relationship Between Fixed Density Speeds and Delta X Speeds.jpg
 
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Good grief. Now I'm wondering whether E really equals mc^2. Surely by now there should be a standard that confirms it or a contrasting theory that attempts to disprove it. :wondering:

It's all out there if anyone is interested in moving beyond The Negative. It appears to be down right now, but here's a link to a number of key papers.

http://64.165.113.140/content/benskin/
 

Bill Burk

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Adams in actuality wasn't very good at theory. The aims for NDR and Zone I are based on a misconception. Ever wonder why the LER for Grade 2 paper for a diffusion enlarger is 1.05 and Adams has a 1.15 - 1.25 for the NDR? Or how ZS film speed testing almost universally results in EIs 1/2 to one stop slower than the ISO speed?

You know I've always wondered that. But I think I just drew it onto silveror0's graph. There's two-thirds stops between the standard metered gray and Zone V. For now I'll ignore other factors that amount to about a sixth of a stop because right now this thought is clear and adding sixths of a stop just makes the thoughts muddier...

That one fact accounts for most of the difference.

Meter reading Zone V minus 4 stops to 0.10 ... versus the standards which take the meter reading minus 3 1/3 stops.

Zone System increases exposure by 2/3 stops right there... And that's not bad.

If you are going to make a mistake in theory and practice with black and white negative large format photography... making an error that preserves traditional pre-1960 increased exposure is a mistake that I'm happy to live with.

Good grief. Now I'm wondering whether E really equals mc^2. Surely by now there should be a standard that confirms it or a contrasting theory that attempts to disprove it. :wondering:

Your graph and your method is great. It is factually what's going on with the film.

In fact, I carry the graph of family of curves with me when I do my "Zone System" based photography. The curves show what you can put on the film and what you can get out of it.

My buddy Jim Moore's catch phrase applies here: "Reality is reality and anything you say about it is just something you say about it."

The curves reflect reality. You can make copies of the graphs and draw lines and put dots on the lines and figure out a whole lot of stuff. But the graphs show what is going to be the density of your film given certain exposures and development.

So draw a line at 1.30 if you want. And then look left and right for when the next Zone hits the line. You can pick your N+1 and N-1 that way.

That's a fine way to pick development times --- because it works.

By sensitometry I come up with essentially the same number of minutes to develop as you do by following Ansel Adams' Zone System prescribed methods. That's because... while his theory may be flawed when it comes to trying to explain what he thinks is going on... His experience based on his real use of film and printing... is not flawed.

Even the oldest Zone System reference I have, Minor White's yellow book, says to place your significant shadow on Zone III.

Now when you place a shadow on Zone III you will expect a density for that to be... about 0.30

If it ends up 0.40 because of flare, nobody will ever know when they look at your print on Grade 2 paper.
 
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Stephen, certainly not to take issue with what you've said, but I'm curious to know if anyone has integrated all that info that's "out there" into a published system that could conveniently be used by photographers in the field (similar to the Zone System). Perhaps it could be called Zone II (that'd really confuse everybody though) or BTZS II.

Well, it's basically about using more accurate numbers and a few sensitometric principles. Phil Davis comes closest to putting it together within pop literature. I've never suggested the visualization aspects of the Zone System need to change. You have already gone beyond what Adams intended by using film curves. I'm only pointing out a couple misinterpretations. I asked about whether anyone has questioned why grade 2 has an LER of 1.05 but Adams recommend a NDR of around 1.20, yet Zone System practitioners don't have a problem printing. This discrepancy always bugged me. Other publications, like BTZS, use correct numbers, but Davis never went as far as debunking Adams, thus it becomes a he said situation.

I've been thinking of an analogy of a 24 hour day. It will be a 24 hour day whether the sun revolves around the Earth or the Earth revolves on it's axis. Does it matter which is right if I can still make it to work on time? I think it does matter.
 

Jim Noel

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Adams in actuality wasn't very good at theory. The aims for NDR and Zone I are based on a misconception. Ever wonder why the LER for Grade 2 paper for a diffusion enlarger is 1.05 and Adams has a 1.15 - 1.25 for the NDR? Or how ZS film speed testing almost universally results in EIs 1/2 to one stop slower than the ISO speed?
The film and paper that Adams used were different than those today. IN most cases, significantly so. Tri-X of today has little if any resemblance to the Tri-X of the 60's. Super XX hasn't been produced in years and many of his images were made with that beautiful straight line film. I occasionally pull a few sheets out of the freezer to use just for old times sake.
The basic reason for the difference in ISO speed, and a practical exposure index has to do with the method used to determine ISO. The developer is different, the exposure is very exact using very accurately controlled light sources, and the film ios fresher than any you will ever get from a retail source.
 

MattKing

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Stephen:

I am always grateful for your contributions to these threads, but sometimes I do wish you would include a signature line with a glossary of acronyms.

"grade 2 has an LER of 1.05 but Adams recommend a NDR of around 1.20"

Can you remind us what LER and NDR stand for please.
 

Old-N-Feeble

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IHA !!!
 

DREW WILEY

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Gotta take Michael to task once again, for something he implied yesterday ... Walll, if hit wahr goot enuf fer Ansel, thet thar lattytude thing mus be
enuff fer me too ... Yeah, sure.. but some of his negs were utter hell to print, and he did try to make a practical science out of exposure as much as
he could. The same kind of subject matter might be damn easy given all the tricks we know today, along with superior gear and supplies. And although most people cannot be expected to routinely plot film curves, I do recommend it at some stage in the learning process, because it helps you see what is actually going on with the film, how films differ between themselves, and in relation to different developers and degrees of development,
and indeed, why even the Zone System has many shortfalls in what it can accurately predict. To this day, when I take a shot, I actually have the
general shape of the SPECIFIC curve for that film back in my head somewhere. So it allows me to place my exposure almost instantly, even more
precisely than Zone theory. About the only time I goof an exposure is in dim light where I don't bother to pull out reading glasses, and read the dial
on my meter incorrectly! Not all films are the same by any means, nor do they themselves behave the same when developed differently one time
to another. Those seemingly tiny differences one curve to another are in fact logarithmic, so can have a significant impact in printing itself.
 
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The film and paper that Adams used were different than those today. IN most cases, significantly so. Tri-X of today has little if any resemblance to the Tri-X of the 60's. Super XX hasn't been produced in years and many of his images were made with that beautiful straight line film. I occasionally pull a few sheets out of the freezer to use just for old times sake.
The basic reason for the difference in ISO speed, and a practical exposure index has to do with the method used to determine ISO. The developer is different, the exposure is very exact using very accurately controlled light sources, and the film ios fresher than any you will ever get from a retail source.

The edition of The Negative that most people read is from the early 80s. Film and paper haven't changed that much since then. Besides, the ISO LER method dates back to the late forties.

As I pointed out in an earlier post, the average gradient for Normal as determined by the Zone System and Tone Reproduction stated conditions is the same. That means that the film is processed to the same degree. The results will be the same, so it can't be about different materials.

The basic reason for the difference in film speed is that the ratio between the speed point and the metered exposure point is different. There is a 2/3 stop difference. Please see the 3rd graph in post #41. The Zone System had a better correlation with the ASA speed before the 1960 b&w film speed standard.
 
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Here is a good example of why rule of thumb processing percentages aren't accurate. Below is a Gamma / Time curve from The Theory of the Photographic Process. It shows the rate of development of the same photographic material processed in different developers. Points M and N show the time it takes to produce the same degree of contrast change between the two curves. As you can see, curve B has to be developed longer to produce the same gradient change as curve A.

Gamma Time.jpg
 

Fraunhofer

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It's all out there if anyone is interested in moving beyond The Negative. It appears to be down right now, but here's a link to a number of key papers.

http://64.165.113.140/content/benskin/

Thanks, this is an excellent resource and seems to confirm my suspicion that the fact that the zone system results in an EI about 1/2 of box speed for most is due to a different definition of film speed and not due to huge inaccuracies in meters, shutters etc. BTW if the latter was the reason some sizable fraction of cases should find an EI above box speed.
 

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Adams in actuality wasn't very good at theory. The aims for NDR and Zone I are based on a misconception. Ever wonder why the LER for Grade 2 paper for a diffusion enlarger is 1.05 and Adams has a 1.15 - 1.25 for the NDR? Or how ZS film speed testing almost universally results in EIs 1/2 to one stop slower than the ISO speed?

I disagree. He simplified a complex subject so that it's easier to apply.
 
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I disagree. He simplified a complex subject so that it's easier to apply.

Sorry, did I forget to genuflect before criticizing Adams? I guess I should have said I assume Adam's wasn't very good at theory because of all the fundamental mistakes in his book.
 
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This is actually a very important subject and I shouldn't have been flip with my previous response. There are two issues here. Did Adams' books contain fundamental errors in photographic theory, especially tone reproduction, and exposure theory? What are the points of contention?

And secondly, could the reason many photographers regard Adams as the ultimate authority on photography is that they haven't had the opportunity or weren't aware of the more scientifically oriented photography books? I personally consider Adams' series as falling into the amateur / popular photography / how to milieu.
 
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