What is Ansel Adam's “Zone System”?

Question

I've heard much of Ansel Adam's Zone system, but I've never quite understood it. What is it, how and where is it used, and is it still useful with modern (digital) cameras? Thanks!

Answer

The basic rule: All photometers are metering the exposure base on middle gray.

Let's say that you have a scene with only middle gray luminosity colour; if you base your exposure on the meter reading for an area of this scene, the picture will be exposed so it's as you saw it.

Now let's say that you have a woman wearing a black dress and a black background. If you calculate the exposure based on the meter reading for this scene the resulting photograph will be a grey dress and a grey background, because the metering is giving you the exposure as if you metered on an area of grey!. To correct this exposure you need to add -2 stops.

The same thing for happens with white. Let's say that you have a woman with a white dress, on a white background. The metered exposure will give you a grey dress on a grey background, because again the metering is giving you the exposure for a grey subject!.Add +2 stops to get the correct exposure in this case.

Now what is the trick. The zone system says that it is up to you to determine how you would like to photograph your scene, and it's up to you to determine where you'd like to put emphasis in your photo.

Its up to you to decide what is black, what is white and what is grey, and to make the final exposure.

What does that mean? Let's say that you have any normal scene. In that scene you have highlights, you have shadows, and you have other areas of middle tone.

Let's say now that you have 2 women, both wearing black dresses, in front of a white background. One of the women is under a spot light, the other is in shadow. It's up to you to decide which woman will have the black dress in the final exposure, as you can't have both exposed to be black due to the differing lighting conditions. The full luminosity range of the picture is the zone system.

If you make a measure on the woman in the shadow's black dress and correct the exposure with -2 stops, then the woman on the spot light black dress will probably get washed out.

If you measure the woman in the spot-light's black dress and correct the exposure with -2 stops then the woman in the shadow will be totally dark.

If you try to make them both appears then you get the average reading between the 2 blacks, and correct with -2stops, then no one will be totally correct.

To summarise:

• If you shoot any scene have a range of luminosity, and break this range into parts, then you have the zone system. Then it's up to you to decide what is black, what is white, what is gray, and make your final photo.

Olympus OM System

I will have as reference the Olympus OM system that have still now the best and only multi-spot metering system, and I wish some one add the same multi spot metering system on all new digital cameras.

From the olympus om 4ti manual I get the example photos.

White

A white example photograph.

you have a white area, if you just metering as it is you get a gray results, but you decide that you like to make it white. You make a spot metering on white and add +2 stops and the results

Black

A black example photograph.

You have a black telephone, if you just take the picture you get a gray telephone. You decide that you wish to see it black, you take a spot metering on the black spot on the telephone and you add -2stops, and the results is a real black phone

Full range luminocity

and a full zone system.

Here you have too many different point of luminosity. If you decide that wish to get a picture that the womans dress must be white, then you make a spot metering on white and add +2spot. On multi spot metering of olympus is more easy, you take 2 spots on white and on skin color, and you have a good average with a not so bright white dress and a good luminosity of the face. and the results

Now to try to show the zone system, I make the picture pixelize and you can see the different luminosity rectangles. The zone system say that every scene have this range and its up to you to decide what luminosity you going to select on you shot. So you select a rectangle spot, you decide what luminosity this have (gray ? white ? black ? etc) you make the measure, correct the exposure and take the picture.

note on this example the womans dress, gets out middle gray, on the previous was an average metering, not a white dress metering, do not confuse the last two photos with the white dress that I am writing on comments.

and is it still useful with modern (digital) cameras?

Yes of course it is. The metering are the same, the scenes are the same, the technique is the same. I say it again, if the modern cameras have multi spot metering then we going to have a real tool for correct exposure.

Not only digital cameras use the same technique but adobe photoshop also use the same technique. Almost on all correction on the images you have see the 3 eyedroped tools. If you do not know why they are there, I tell you is there to help you correct the zone system of your photos. See this example and make later your test to find out how to use them:

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