Zone System Beginner

[Gem Singer]

Joe,

Zone 3,4,5,6,7 is five stops. Count the zones, not the difference between them.

[Joe Smigiel]

... What if I had a gray card and set it in the scene and metered it? My meter would show exactly what the exposure should be for that tone. But what would happen to the rest of my scene?

That would depend on the lighting and subject conditions. Imagine a foggy landscape where you meter the gray card and set the exposure accordingly. Everything will be middle gray with very little range. Dull, drab... In that situation, you probably want to meter the darkest tone and not the gray card, place it low and overdevelop the film to add contrast to the image.

Conversely, if it was a normal sunny landscape and you metered the gray card, the shadows and highlights would probably fall in acceptable zones and you could get away with it.

[Joe Forks]

Gem,
10-4, Thank you for clarifying that. Let me ask on e more directly related question. So this translates exactly to EV as well? I've got an EV of 10 for shadows and 15 for highlights I want to keep, that's 6 stops or N-1. If this is correct it directly conflicts what "ejohnson" wrote in Using the view camera, the source of my confuddlement.

Best
Joe

[Gem Singer]

Joe,

Just to make sure, I got out my trusty Pentax spot meter. Starting with EV 10 and opening to EV 15 increases the exposure by five stops.

I can understand your confusion.

[Joe Forks]

Joe,

I can understand your confusion.

Gem,
Absolutely. There must be hundreds of noobs with 1 stop errors in calculating zone system development based on ejohnson's examples. I just double checked what he wrote and he was at least consistent in counting the difference in stops rather than the total number of stops contained in the contrast range.

The total number of stops makes much more sense of course, because those are exactly the zones that you want to retain detail.

I'm wondering if anyone has noted that error in that chapter before?

Best
Joe

[Nathan Potter]

Guys, an EV range of 10 to 15 is six brightness levels but a difference of 5 stops. This is just a semantics problem that you need to work out in your mind. I remember being confused about this until I just simplified it in my mind - that is I mentally focused on EV values as an absolute density on the negative.

I generally render the tonal values of a scene as how they will appear on the negative while ,I think, most people will try to visualize the scene as a print rather than as a negative. The print visualization is a more logical approach but involves consideration of both the negative and print processing conditions. I simplify this in my mind by realizing that if I can get the contrast range of the negative something close to logD 1.25 then I know I can print it. There are many variations in zone system implementation and you'll develop your own simplifications as you start actual practice but the main thing is to stick with it because it will appear very confusing at first reading.

Nate Potter, Austin TX.

[darr]

Darr,
I'm trying to learn the zone system as well so forgive me for this question but since you posted the example I had to examine it to see if I understand.

Firstly, aren't we looking for a 5 stop contrast range for (N) normal? In your first example Zone III to Zone VII is 4 stops so why wouldn't that be N+1? Then following that logic your second example should be (N) as it is 5 stops.

I'm just asking, so don't shoot me, this was for my own exercise.

Best
Joe

Hi Joe,

I would never shoot you, well maybe with a camera

Anyhow, if you look at example #1 we do have a five zone spread:
Zone III, Zone IV, Zone V, Zone VI, and Zone VII
You need to count the zones, not the space between them.
And in example #2, it is a six zone spread, so that is why we adjustment our development time for five zones.
In the beginning I use to call them stops as well, and I think it screwed with my math, so I have learned to call them Zones and maybe that will be helpful to others.

Best,
Darr

[Joe Forks]

Guys, an EV range of 10 to 15 is six brightness levels but a difference of 5 stops. This is just a semantics problem that you need to work out in your mind. I remember being confused about this until I just simplified it in my mind - that is I mentally focused on EV values as an absolute density on the negative.

Nate,
Thanks. I definitely understand what you are telling me. I just wanted to note that is not what is written in "using the view camera". Just look at the bottom right of page 91 and he clearly makes the same mistake citing a zone III to Zone VII range and calling it four stop range. That is literally incorrect, it's a 5 stop range.

Thus the source of my confusion.

And Darr, thank you very much, I got it now!

[Donald Qualls]

I'm just going to insert here that I've read several mentions of adjusting development times, when in fact what's needed is to adjust the contrast of the finished negative. Yes, the commonest way to exercise this control is by developing for more or less time, but this also changes the film speed, requiring you to adjust the total exposure after you decide what development a scene is going to call for. It's also possible to alter negative contrast by changing developer (which will probably also require adjusting film speed, though possibly by less -- especially in the n-minus direction -- than changing development time) or, my preferred method, by altering agitation.

Altering agitation doesn't work in a Jobo or BTZS processing environment, where constant motion is required to process with too little developer to cover the film while it stands between agitation cycles, and in my experience doesn't work well in trays (the edges of sheets will develop more than the centers when attempting a contraction, because it's almost impossible to keep the stack perfectly squared up), but it does work well for roll film in tanks and for sheet film in tubes with enough liquid to cover the film while the tube stands.

I consider agitating every three minutes (compared to the standard one minute cycle) equivalent to developing 30% less, which is about N minus one and a half with most film-developer combinations. Obviously, it's easy to add a little time to get to N minus one -- and since you've added a little time, you don't lose film speed (in fact, you may gain a little bit, though in my experience too little to bother compensating). Similarly, agitate every fifth minute and you'll drop another step, roughly to N minus three, but you can get N minus two by adding a little time (testing might reveal that two minutes and four minutes are perfect N-1 and N-2 agitations).

Key to this method is that shadow development is practically independent of agitation, because the halide has received so little exposure that local exhaustion or inhibition by developer oxidation products (the two main contrast controlling mechanisms) don't set in; thus, altering the frequency of agitation controls the amount of inhibition that affects the most exposed areas: more agitation means more development.

The applicability to Zone Sytem here is obvious -- if you're willing to use a development method that's amenable to agitation control (deep tanks, filled tubes, or inversion type tanks -- or trays with a single film or layer of films), you can, with a little testing, learn to adjust contrast without adjusting processing time (there's even a range of N-plus available, by agitating every 30 seconds or continuously -- in my experience, continuous agitation goes a bit more than N plus one, but not quite N plus two, compared to a one minute agitation cycle -- but adding a little time and gaining a small amount of speed is much less worrisome than losing speed by cutting time). For my own work, I've generally set my N based on agitation every third minute, which gives me a good range of both expansion and contraction without any change in film speed.

[Bruce Watson]

Adjusting development by adjusting agitation is certainly an interesting idea. Nice out-of-the-box thinking!