The Zone System and Why You Should Care (Even if you shoot digital)

Posted on May 18, 2011

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I just started this blog, and already I see the need to lay some ground work on the Zone System. So much has been written about this that this post is entirely redundant and superfluous, but I already had it in the can, so it is easy for me to repost. If it interests you enough to ask questions or do further research (or god forbid play with your digital camera), it’s done its job.

Introduction

Essentially the Zone system is just a way to think about the relative values of objects in an image. Your eye does a fantastic job of balancing things out, but a camera “sees” things differently and does not have the ability to balance this out for you.

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 8×10 view cameras. A very basic understanding will vastly improve your photos.

The Zones

Ansel 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, a person’s face – 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. (For spot metering, for averaged metering, it will attempt to average all the components in the image  around Zone 5.)

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 values of two objects in a picture (their metered values) will never change (barring filtration).

4)      Different media can record different amounts 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.

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

Geek Stuff: 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. Your lens may not have all of these f-stops, which will have some effect on your dynamic range.

f-stop number vs. aperture size

f-stop number vs. aperture size

Just remember: big numbers, little holes; little holes, less light. (They actually do the same thing with shutter speed so 400 = 1/400th, so it shouldn’t be so hard to get used to.)

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.

1/400, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1, 2s

Geek Stuff: You’ll notice that the scale is not perfectly linear  – 1/15th is not half of 1/8th, somebody just figured it was easier to be close enough, roll with it.

Let’s look carefully at this scene again.

Metering

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 do this because the depth of field is usually more crucial to me than freezing action, you can also put it on Shutter Priority). 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.

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 three 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.

3)      Since I metered on the dog, the dog is in Zone V – whatever you meter on is always in Zone V. The snowman is 7 zones away in Zone XII. Um, the scale only goes to X, but you say we can handle it. Huh?

Adjusting Relative Zones

However, what is not completely obvious, and this is what makes the system 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 V. So when I metered on the dog the snow man was 5 + 7 zones = Zone XII, pure white. And when I metered on the snow man, placing it in Zone VII, the dog was well 5-7 = -2, pure black. But we probably don’t want a grey dog or a grey snowman. Remember whatever we meter on will be grey (B&W), or in the middle of the dynamic range (color).

Dynamic range and the zone system example

Adjusting the relative exposures in an image

The trick is to know that now I can put the dog in say zone III, where there is good shadow detail by metering on the dog and underexposing two stops (from 2,8 to 5.6) putting the snowman’s highest highlights in Zone IX. 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 for my lens, how do I move down? Simple, you switch to Manual mode, keep the same aperture, and halve 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.)

Post Processing Note: Contrast in a print is relative, not absolute

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 when you take the photo, to get the image you want in the darkroom/Photoshop.  (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. Also, Bruce Barnbaum has since extended the zone system to overcome some of these issues.) When you work in the darkroom (whether actual or virtual) to perfect your image you have all kinds of controls (dodging, burning, filtration, and bleaching) that allows you to achieve local contrast controls. But, you have to have the information recorded correctly to make that happen. You have to be able to look at a scene and meter on it to say “I want to make sure I get good detail on the dog, because this is a dog portrait, and maybe I should (wait for different light, change the background, adjust my settings correctly, etc.) to get the image I want.”

A Step Towards a Basic Exposure

I find it convenient to put Zone V in f/11-16. With my lenses, this gives me a full tonal range and makes it easy for me to do my math, plus my DOF is pretty much guaranteed for most shots. In other words, if I meter on something in good light, and want it in Zone V, I can be pretty sure that f/16 at 1/15 of a second will work. Even if I’m off by a stop either way, I’ll get usable negatives with plenty of range. So that would look like this for both aperture and shutter speed.

Zones

0

I

II

III

IV

V

VI

VII

VIII

IX

X

f/2.8 f/4 f/5.6 f/8 f/11 f/16 f/22 f/32 f/45 f/64 f/90
1/400 1/250 1/125 1/60 1/30 1/15 1/8 1/4 1/2 1 2s

Color

The same concepts apply to color as well, as each object still has a relative reflectivity value. You can still block shadows and blow highlights. I would suggest you research other, more qualified, authors on this as color these days essentially equals digital and my Luddite nature has not quite groked all of the intricacies of that medium (or even color, for that matter).

Did this Help?

This is my most read and least commented post. I wrote it 3 years ago and still get hits on it every day. If it helps you, or confuses you, please let me know!

P.S. Who Are You and Where are You From?

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Who is visiting me from the Ukraine?

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Posted in: Photography, Zones