Well first I did mean that everybody's numbers will be different because we are also useing different lenses, cameras, enlargers, chemical scales,etc.
Back in the day (pre ISO) it was widely held that a meter was calibrated to determin an exposure to yield18% gray. That is the assumption Ansel made in the beginning. I eventually used the exposure formula Ansel mentions in the "Basic Photo Series" where the film speed determins the key stop and then meter readings in candles per square foot at the key stop are the shutter speed for Zone V placement.
With my definitions I mean an N+1 is Zone V placement yields a Zone VI density in the print and so forth. N-1 is a Zone VII exposure yields a Zone VI density in the print and so forth. Even if one disparages (As everyone has the right to do) my choice of definition I see no intuitive method except to use a similar definition of some kind (pick a Zone). The whole point of the Zone Sytem is to link sensitometry to the everyday problem of determining, while in frount of the subject, how one wishes the print to look.
After I made several series of the prints to prove out what I was getting I took my density readings for each Zone averaged them and used that value as a target for the rest of my testing.
In my testing I used a 9 Zone target made of ND filters in frount of a light source so camera flair was automatically taken into account. Once I had normal I tested until I got the density change I was looking for and then plotted the curve for that time both plus and minus. I found that Zone III and IV were more influenced by exposure than development and after all it is a Zone not an exact value.
[I]For starters, in the ZS, and I assume you are thinking you are using the ZS, all development times are based around the "normal" time for any given film/dev/dilution you are using. Secondly, the zones don't move from one place to another on the curve as you seem to imply.
Normal is only part of the story and if Zones don't move what's the point? What is N+ and N- supposed to be? If you are in frount of a subject and you place something on Zone IV and the high value falls on Zone X to me thats N-1 VII moves to VI 10 moves to VIII with D-23 and Kodalk on Super XX. Without considering the specific film /developer what do you call that situation? And if Zone X is not "moving" to Zone III whats it doing?
I should say moves to Zone VIII (good thing I'm not a keyboarder for a living...LOL)
I fully believe that when commenting publicly in these forums that we should be prepared to be challenged in what we say. So, I'm challenging you on this one particular assertion that you are making as it is the one single thing that is sticking in my craw in this discussion.
With my definitions I mean an N+1 is Zone V placement yields a Zone VI density in the print and so forth. N-1 is a Zone VII exposure yields a Zone VI density in the print and so forth.
You have already stated that your "normal" calibration is based off a Zone V density of between .85 to .95, or .9 to take the middle------ok, that's your choice, I don't understand it, but that's your choice. But your discussion of expansion and contraction of the negative is patently wrong as it relates to the ZS as I see it---your "definitions", as you call them, are a mutilation (no disrespect intended) .
Any film/fev/dilution combo has one "normal" development time that achieves a desired negative density at a particular zone. In my case (and most that I've seen) it is a Zone VIII density of 1.3; I saw on Alan Ross's website that he is experimenting with calibrating his normal development time based off a Zone IX density of 1.45. You have stated that yours is a Zone V density of .9.
You appear to be stating that your expansions and contractions are occurring along the same curve using a single stated development time of 8 minutes with whatever film and developer it was. This is impossible if you claim it is the ZS-----each expansion and contraction has its own curve, defined by a development time needed to get the curve to cross the target density line at the proper zone.
To back up what I'm trying to say, I've included a graph to try and illustrate it. It's a simple set of simulated straightline curves that assumes the correction for EI (hence the reason all the curves merge at Zone I). The "red" indicates what I'm saying and the "blue" is what I think you are saying; the solid black dots are the densities you stated earlier for those zones.
Sorry, Chuck. I'm lost. What your curves are showing me is that what he's saying is not at all what your "blue curve" shows. What I think he's saying is more like the whole set of curves you are showing. I think you guys are talking across each other's bows.
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Although I have stated it empirically I think we mean the same thing. To restate in different terms my normal is that curve which contains the point where a Zone V exposure intersects with 0.90. N+1 is the curve which contains the point where Zone V exposure intersects 1.10. From a visualization standpoint the Zone moves or transforms is perhaps more precise.
I am choosing only certain of the infinate number of possible curves by defining certain aim points and using only those curves that meet at those points. When standing infrount of the subject I am making a choice of which value is placed and another for the developing strategy. I could look at the problem from the perspective of a luminance value which"falls" on zoneX being processed to yield a zone VIII density in the print but it was always easier to think of it "moving". So to put it in curve terms I am choosing to process the film using the time that yields the curve where a Zone VII exposure yields a density of 1.10 which is also (in this example) the curve which contains the point where a Zone X exposure (luminance value) yields a density in the negative of 1.50 which I call (arbitrarily) N-1.
You are right the Zones donot move along the same curve but that also is not what I have been trying to say.
I always found that a curve set without the zone system definitions and the short hand associated with it virtually useless in the field. The concepts of "place" "fall" and of Zones "moving" with development may be scientifically imprecise but they are practical and intuitive in use.
Steve - I don't think we've ever talked about this, and if so, it was a LONG time ago.
Originally Posted by Stephen Benskin
What reason did Jones give for this?
Originally Posted by Kirk Keyes
I know this will not come as a surprise to you. It's the reason for all the photography standards, and another important component that is never discussed, yet is key to film speeds, negative density ranges, and even Zones. Jones was referring to psychophysics.
OK, I think I see what you are saying and I think I know how Fred Picker felt . It's not for me and it doesn't have to be but I was just trying to understand what you were doing, it wasn't clear. It's more important that it works for you, obviously. Perhaps you should call it, AS for The "Analogsnob System".
I am choosing only certain of the infinate number of possible curves by defining certain aim points and using only those curves that meet at those points.
Whatever we call it as long as we do it on film!