Exposure estimation is a completely different thing.
Since you say you use 35mm (Nikon FM), you can rely on your camera lightmeter to give you an average of the amount of reflected light form the scene in front of you and put you in the ballpark of exposure needed.
From then on is a matter of experience/good eye/luck to open/close a stop or two otherwise bracket to get better color saturation, etc.
Depth of filed is another factor you may want to look at, sometimes a shallow depth of filed (lens fully open) can give a 3-D feeling to the picture.
PS for 35mm/digital there is the simplified zone system infomercial
Originally Posted by rhys
Last edited by titrisol; 05-03-2006 at 01:25 PM. Click to view previous post history.
Mama took my APX away.....
The Zone System as Adams describes it uses spot metering. The goal is to test your materials, so that you can previsualize the relationship between tones in the scene and tones in the print, and get a negative that contains all the information you want to appear in the print. It might require further manipulation at the printing stage, but better to have a negative that's in the ballpark, so you don't have to employ extraordinary measures.
You can spot meter with a handheld meter, or with an in-camera spot metering. Matrix metering tries to do the spot metering automatically, but it makes assumptions about your composition that you may or may not agree with. Spot metering puts you in control.
"Moonrise" required extraordinary measures. Adams based the exposure on the value for the moon--exactly the opposite of the Zone System, which follows the older principle of "expose for the shadows, develop for the highlights." He exposed for the highlights, and then locally intensified the shadows on the neg, and dodged and burned to get everything to look good on the print. On the other hand, he knew that this was probably the best way to get the shot in those days, since the contrast range between the moon and the landscape is huge. Employing the Zone System in the normal way by placing the shadows on Zone III and reducing development for the moon would have produced an even worse negative, because the range would have been too great to compensate for in that way. Today maybe he would have put an ND grad filter into the equation and done it differently.
So for a normal image employing the Zone System, the basic idea is to test the film so that the darkest area where you want detail to show in the film (usually Zone III) always will have detail if you spot meter for Zone III.
Once you've tested for film speed, you test for development time, so that you can spot meter the brightest area where you want to see good detail in the print (usually Zone VIII), and you can adjust the development time so that wherever that area falls, you can make sure it will have detail in the print. If the light is flat, you'll use a longer development time than normal, and if the scene is very contrasty, you'll reduce development time. If you represent the distribution of tones as a histogram, like you might with a digital camera, extending development time stretches the histogram, and reducing development time compresses the histogram.
As I understand it, it took Ansel Adams 20 years to get the print he wanted. The University of Arizona at Tucon will be glad to give you a copy of any of his negs. Pat
Originally Posted by Lee L
Originally Posted by Stephen Benskin
I don't doubt you are right, but OTOH, the 21 steps are 3x the approximately 7 stops defined by Jones. So the 21 step chart which goes from 0 - 3 or 4 in density may have earlier roots as well.
And, the inventors of Kodachrome were musicians too, so there may be quite a few harmonics resonating in the science of photography.
Also this to say, rhys, that Adams stated that the quick exposure method should only be used as a LAST RESORT. An understanding of the Zone System and the use of some sort of light metering is the way to go. Guessing is just that. Either you stand a chance to waste a lot of film or you should split your powerball ticket with us.
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Originally Posted by Photo Engineer
You're right, the difference is the 21 steps gives more information in sensitometric testing, but the 7 1/3 stops is the statistical scene luminance range as defined in Jones paper, The Brightness Scale of Exterior Scenes and the Computation of Correct Photographic Exposure, published in JOSA in 1941.
I believe the difference between the idea of the 21 step and ~7 stops is that one is for sensitometric purposes and the other for tone reproduction. The Zone System uses the seven stops for Normal because that is the average luminance range for scenes. From a tone reproduction point of view, Normal is based on 7 1/3, and so is Kodak's for that matter.
I do believe one of the weaknesses of the ZS is that it doesn't do sensitometric testing and then place the scene luminance range on top.
Steve, Ron... could (would) either of you elaborate here? My experience with the ZS literature is an eleven stop range—zero through 10—not 21 or seven or...
Originally Posted by Stephen Benskin
What have I missed?
I have read the Adams book and the Picker book. For my money, "The Practical Zone System" by Johnson, is head and shoulders above either one when it comes to an easy to understand, straight forward explanation of the ZS. The Picker book is good as far as it goes, but it ends with normal development. It does not go into plus or minus develpment and metering of scenes requiring other than N develpment at all.
This is where the ZS really falls short and I feel leads to much confusion. I believe Adams came up with the O - X range for paper based on the Munsell scale. He then tried to shoe horn it into scene luminance, but the range for his testing procedures says something else. Adams range for testing I - VIII is seven stops, so the range for calibrating your development closely corresponds to tone reproduction theory. Without going into the discrepancy of his density range to the tone reproduction density range, normal processing for both ZS and tone reproduction is approx. CI 0.58.
Originally Posted by bob01721
Others on this forum know Davis' version better than I, but I believe he attempts to solve the discrepancy between a ten Zone paper scale and a shorter scene luminance range. I personally think he makes a valiant effort to make the faulty original ZS concept work.
No doubt you are right, I was just trying to inject a little levity into it. Read my post again regarding 'music'...
Anyhow, the situation is as you describe and the 21 step chart is the effort of engineers to get more detail.
The intent of Adams and others was to try to contain the usable range of the zones to the center straight line portion of the curve, because, as you say, it is the normal luminance range and also is the best part of the negative.
If you slide the 7 zones downward to the toe or upward to the shoulder, then you get compression of data and have to 'uncompress' the data by adjusting development time accordingly.