The Zone System and Why You Should Care.

Yes, this is so simple as to be nearly over-simplified, but hopefully not unusable.

Before Ansel Adams photography was pretty much a crap shoot: how the process affected the product was not well understood. What Ansel Adams did was develop a very simple system that let you “previsualize” how a print would look before you took the picture, developed the film, and printed it.
It is important to realize that the actual Zone system has applications in all three phases, but for now we will concentrate on taking the picture. While he developed the system for B&W film, this aspect of the system is as applicable to modern digital cameras as it is to 8x10 view cameras. A very basic understanding will vastly improve your photos.
He divided the black and white spectrum into 10 zones:
Ansel Adams' description of zones (geared towards black and white printing)
Low values
Zone 0 Complete lack of density in the negative image, other than film base density plus fog. Total black in the print. We will omit zone 0 from the remainder of this tutorial; zone 1 will be considered pure black.
Zone 1 Effective threshold. First step above complete black in the print. Slight tonality, but no texture.
Zone 2 First suggestion of texture. Deep tonalities, representing the darkest part of the image in which some detail is required.
Zone 3 Average dark materials. Low values showing adequate texture.
Middle values
Zone 4 Average dark foliage. Dark stone. Landscape shadow. Recommended shadow value for portraits in sunlight.
Zone 5 Clear north sky (panchromatic rendering). Dark skin. Gray stone. Average weathered wood. Middle gray (18% reflectance).
Zone 6 Average Caucasian skin value. Light stone. Shadows in snow in sunlit snowscapes.
High values
Zone 7 Very light skin. Light gray objects. Average snow with acute side lighting.
Zone 8 Whites with textures and delicate values (not blank whites). Snow in full shade. Highlights on Caucasian skin.
Zone 9 Glaring white surfaces. Snow in flat sunlight. White without texture. (The only subjects higher than Zone 9 would be light sources; they would be rendered as the maximum white value of the paper surface.

Here are the important things to know about the Zone system:
1) No matter what you point your camera at, your black dog, a snowman, the meter in your camera will always meter that to be Zone 5. This means that whatever you meter on will come out as neutral gray in the print.
2) Each Zone contains twice as much light as the one above it, and half as much as the one below it.
3) The relative reflections of two objects in a picture (their metered values) will never change (barring filtration).
4) Different media can record different amount of light (dynamic range).
a. B&W film 10 + zones (This is where developing and printing controls come in, for this discussion we will say 10 zones.)
b. Slide film 7.5 zones.
c. Digital sensors 6-7 zones.
Dynamic Range
Okay, what does this mean? Say you are looking at a scene that has both shadows and highlights. Your black dog in front of your snow man and you have an in camera meter set to spot meter (instead of some broad average, it will become clear why to do this in a bit). You point at the dog and take a picture. Then you point at the snowman, somewhere where the sun is shining on it, and take a picture. (This is where digital is awesome, you can do a similar experiment right now. In fact, you should do this right now, find something with high contrast and take these two pictures.)
In the first picture, you will have good detail on the dog, even in the shadows you can see the hairs, but the snow man is completely” blown out” (white). In the second picture you have good definition in the snowman, albeit he’s kind of grey, but the dog is “blocked” (a black blob). These are the typical hallmarks of point-and-shoot photography, blocked shadows and blown highlights.
You cannot “fix this in Photoshop”! This is just bad photography that comes from not understanding the tools. Whether it is a negative or a digital sensor, if you don’t record the information correctly, you cannot ever retrieve it. We’ve had the Zone system for about 100 years, it’s time to learn how to use it!
Aperture/Shutter speed
Aperture priority:
This means that we control the amount of light coming in by changing the size of the shutter opening. Each f-stop on the camera actually doubles the size of the opening, or lets in twice as much light. Wait a minute, where do we know that from? Oh, yeah each zone is a doubling of the light from the zone before. So we can control zones by controlling our aperture.
Shutter speed priority:
Likewise, and you may never have noticed this before, but each time division on your camera is half or double the one on either side of it. So we can control zones by controlling our shutter speed, too.
Let’s look carefully at this scene again.
So now let’s just say we put the camera in Aperture Priority mode. This means that I pick the f stop and the camera automatically picks the shutter speed for me. I meter on the dog and adjust my camera until the meter needle is in the middle. The dog reads 2.8, then I meter on the snow, and the snow meters 22.
The scale on your camera goes like this:
f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/45, f/64, f/90, f/128,
It’s a weird scale because it is in the radius of the circle so it goes up by squares, and not linearly, and also it’s a fraction so big numbers equal little holes.
Just remember: big numbers, little holes; little holes, less light.
So from 2.8 to 22 is seven “stops” (2.8, 4, 5.6, 8, 11, 16,22) which for us will be 7 zones. This is our dynamic range.
Okay, notice two things:
1) Almost all of our media will handle this dynamic range. (And in fact although you can easily record 10 zones on B&W Ansel rarely used more than 7.)
2) In our example, the dog and the snow man will always be this far apart.
Adjusting Relative Zones
However, what is not completely obvious, and this is what makes B&W film so freaking cool, is that I can place the dog in any zone I want. The readings the camera gave are just the readings to expose the metered object in zone 5. So when I metered on the dog the snow man was 5 + 7 zones = Zone 12, pure white. And when I metered on the snow man, the dog was well -2, pure black.
The trick is to know that now I can put the dog in say zone3, where there is good shadow detail by metering on the dog and underexposing two stops (from 5.6 to 1) putting the snowman’s highest highlights in Zone 10. If I thought that there was too much pure white and that would blow the highlights out, I could move the dog down one more zone, losing some shadow detail, but getting the snow detail.
Wait! I’m at the bottom of the scale, how do I move down? Simple, you switch to Manual mode, keep the same apertur, and half the exposure time. Because while we have been adjusting zones using aperture, you could also have done it using shutter speed. (With modern digital cameras you can also adjust the “ASA” or “film speed,” but I won’t go into that here.)
The concept is that in many situations you will have to decide what is going to have detail and what is going to be problematic, but that you are indeed in control of this. (Again, 7 zones is pretty contrasty. In The Making of 40 Photographs, Ansel shows many of his classic shots with certain portions blocked or blown because of the choices he made. This book is an awesome treatise on putting the zone system into use, although that is not necessarily the intention.)
Color/Digital Applications
The same concepts apply to color/digial as well, as each object still has a relative reflectivity value. In general the more information you can get in the shadows without blowing out your highlights, the more you can do in post processing (ie "fix it in Photoshop"). In digital this means moving the histogram as far to the right (coincidently called "pushing to the right") as you can without the highlights going off the graph. In fact the histogram is actually a graph of your dynamic range. So digital cameras are way cool, especially in how they expose information to you.


Tropical member
Hey windtickler,

It's really great to see you mentioned the zone system. I agree! It's a great concept and every photographer should take a look of this cool stuff. The application is not limited in B&W films. I agree with you, with all the instant digital imaging, it could be a fantastic system to learn contrast, toner richness and dynamic range....

This article actually remind me a lot of good ol days in the dark room, I am the one fell in love with the zone system... you got to love all the chemicals... windtickler... : )
What's your major photo subject??
I used to use Pentax 645 and Fujinon 645 for street portraits and some natural subjects. Speaking of Zone system, I felt the most useful tool to me (in my subjects) was adjusting the relative zone. Frequently, the landscape subjects in my photo are out of the capturable range of the films. Sky is too bright, rock is too drak... so I need to use this technique to compress the relative value. Over expose the film (shot iso 400 as iso 100) and combine with the reduction of the develop time in the dark room... this way will allow me to capture the most detail in all range. it compressed the whole b&w zone. On the other hand, if the tree bark and green leaves are too close in their relative values. I under expose the film (iso 100 shoot as iso 400) and extend the develop time to reach the correct density. It allow the film to expend it relative values. I am not sure how could you do this in the digital camera though? can you explain it a bit more? Do you take more than more shots and combine them into HD?

Anyway, Ansel Adams' zone system is cool, he surly earn the "HD" title in the B&W films.
As I mentioned that my treatment was a GROSS oversimplification and I didn't get into some of the things you mentioned specifically because that is where film in and digital diverge.
So you discuss some film-specific techniques, specifically development compensation. If you have all of those capabilities I suggest you track down Bruce Barnbaum's book on photography, he has extended the zone to beyond 10 useful zones and takes care of some of the limitations of the 10 zone system. He's a local guy, too so you can take classes from him. I religiously put my shadows in Zone V and worry about the hightlights later. Sometimes successfully, sometimes not ;-) I have a couple of rolls of film with Zones up to XIII on them that sit on my shelf while I contemplate how to develop/print them. (B&W negatives can hold at least 15 zones, but you can ony print 10).
One item you brought up that I alluded to briefly is how to increase separation in the field. I use filters to do this for B&W, but again that is a separate discussion that does not quite transfer directly to the new world order. I also use development, although the last time I did this I got a negative that took 30 min under the enlarger to get a decent print!
In digital the effects of filters and also increasing dynamic range can be handled using, as you suggest ,HDDR (of which I hear Chris Scoones has done a lot of work), and adjusting the RGB values in the field/using Photoshop. Some things HDDR works well for, some not so well. It's better for static things. I quite frequently use a similar technique with film where I will put my camera on a tripod, for instance and shoot 1/2 of the exposure of a mountain range while it is forelit, and then shoot the second 1/2 of the exposure as the sun sets over it. I've also used this for city shots at night: you get great definition in the buildings without the lights blowing out. In this case you are essentially doing a double exposure first for the shadows and then for the highlights.
There is nothing new under the sun.
I do actually have darkroom if you or anybody else would like to come over an play. I do mostly landscapes and water scenes, but will shoot anything that catches my eye.