As a full-time family portrait photographer, I continuously strive to improve my skills. And I love to share what I have learned along the way. This post is designed for the photographer that has a good digital SLR camera but has been afraid to venture off the "automatic" settings. You and your camera have so much more potential.
I cannot guarantee that you will be as good as Ansel Adams after reading this post, I'm not quite that amazing. What I do want to teach you, however, is a technique that will help you move closer to getting the exposure of your image correct in the camera, not relying on your camera's automatic settings. If you consistently practice the approach covered here, it can help elevate your photography game a notch or two.
A Little Background
Back in the 1930's, Ansel Adams and Fred Archer developed a technique to ensure that their black and white photographs were properly exposed. Their "Zone System" proved to be a great way to adjust the amount of contrast in their final prints. When done properly, especially in black and white photography, you create a final image that has a good range of both light and dark elements. Ideally, all of the "zones" are represented in the final print. If you're not familiar with Ansel Adam's work, do a quick internet search now. You'll quickly find quite a collection of stunning black and white images.
What will stand out to you is that each photograph has a descent amount of both light and dark areas, and no lost details at either end of the tonal range. That's very characteristic of his style and quite difficult to consistently achieve. For example, within the same photograph you'll see details and texture along the face of a snow-capped mountain (which would normally be blown out and over exposed), and just as much detail in the very dark shadow side of a pine tree (which would normally be too dark to glean any details from.) If you've tried taking such a picture yourself, you know that loosing details at one end or the other is typical. Capturing sufficient detail at both ends of the spectrum is almost impossible.
Use an SLR Camera
What we are about to do will not work with the camera built into your cell phone. Little pocket point-and-shoots probably won't work either. You need to have a camera that gives you the ability to change metering modes. You also need to be able to adjust the shutter speed and aperture values. An entry level SLR, either digital or film will work. Black and white film, color, either way will also work. If this paragraph just freaked you out, you may need to go through your camera's owner manual before returning to this point in the blog. I'll wait ...
Okay, your back. Good.
Sometimes a blessing but often a curse, in automatic mode our cameras work hard to achieve a nice, balanced, properly exposed scene. That may work out just fine if you take a picture of a well-lit scene with a good range of light and dark, and there's nothing in the scene that will "fool" the camera into making a bad decision about the exposure. In the real world, however, many of the moments we try to capture with our cameras are far from perfect.
A Couple Experiments
I was amazed the first time I tried this. Then it all made perfect sense. You'll have an "Ah Ha" moment too if you grab your camera and follow along.
First experiment: tape a blank piece of white paper up on the wall, about eye level, turned on a landscape orientation. With your camera in a completely automatic mode, stand a few feet away from the paper, focus on it, then zoom in (or walk towards) the paper until it completely fills your viewfinder. Take the picture.
Second experiment: tape a black mat board to the wall. Repeat the experiment just as above.
Results: If you did this correctly, and your camera performed as intended, you should have two images in your camera's memory that look almost identical. Neither one should be white, nor black. Both images should be a similar neutral grey. Huh? What went wrong?
As I mentioned earlier, our cameras work hard to achieve a properly exposed scene. The camera takes some or all of the scene into account (depending on the metering mode, we'll talk in a bit) and makes decisions to balance out the exposure. The camera's goal is to produce a scene that has an overall average exposure, nice and neutral.
When you took the picture of the white paper, the camera saw a bright, over-exposed scene. It then adjusted down the exposure until the scene appeared what it considered normal.
Likewise, when you took a picture of something black, the camera thought that the scene was too dark and underexposed, and made the needed exposure adjustment to brighten things up.
In both cases, our cameras did a bad job of understanding what we wanted. We wanted a picture of a white piece of paper. And we wanted a second picture of a black piece of paper.
The Zone System Explained
In both cases, that medium grey color that the camera created for us is similar to what Ansel Adams defined as Zone V (roman numeral five).
Zones I through IV (one through four) are darker than Zone V, and Zones VI through X (six through ten) are brighter than Zone V.
Here is a list of zones that we can expect to see in our pictures created by our DSLR cameras:
Zone III - dark material that still has some visible texture
Zone IV - average dark foliage; shadows in a typical landscape
Zone V - dark skin tone; deep blue clear north sky at high Noon; 18% grey card; average grey
Zone VI - normal Caucasian skin tone; shadows on snow
Zone VII - very pale Caucasian skin; white with visible texture
Our cameras have trouble recording Zones 0, I and II on the dark side. They also loose a lot of detail in zones VIII, IX, and X.
SIDE NOTE: this is one of the reasons why film photographers get frustrated with the take-over of the digital world. Film can record a broader range of tonal values, picking up Zones II and VIII and some films reached even further. The digital age has generally produced images with less range, and therefore said to contain less contrast.
Your Camera's Histrogram Explained
Does your camera have a little graph on the back panel when you're viewing a picture? If you look closer than you ever have before, you may notice a few vertical lines on the graph area. If your histogram is like mine, it is broken up into five zones. Ah Ha. The five areas represent Zones III through VII. And you guessed it, Zone V is in the middle!
Go back to the two pictures we took of the white and black paper. Now that you know what the histograms represent, they should both be spikes in the Zone V area. Pretty cool, huh?
Now that you know how your camera is compensating for what it "thinks" you want as the final exposure, you can override that decision to tell the camera what YOU see and how YOU want it exposed.
A Few More Experiments
Take another look at the picture of the white paper that you captured earlier. I know, it looks grey. We're going to fix that.
Did your camera record shutter speed, f-stop, and ISO data for you? I want you to write down all three of those values before we move to the next step.
Third Experiment: Put your camera into "manual" mode. Don't panic. I'm here, I'll coach you through this. Now plug in all three of the values I asked you to write down. We want to use the same shutter speed, f-stop, and ISO values that the camera decided to use in our first experiment.
If you point the camera right now at the white paper and take a picture, you should have exactly the same grey exposure you had when the camera was in fully automatic mode. Try it to be sure we have the values plugged in correctly.
Now I want you to leave two of the three values alone. We are going to increase the exposure by slowing down the shutter speed. And here's how. Take what ever timing value the camera used and cut that value in half. In other words, if your shutter was 100, that means that the shutter opened up for one one-hundredth of a second to achieve the given exposure, Zone V. If your shutter was 100, set it to 50. That means we will will slow down the shutter. Rather than being open for 1/100th of a second, we'll stay open twice as long, 1/50th of a second.
Point the camera at the white paper hanging on the wall again. Take the picture.
If all went well, you should be able to observe a couple interesting differences from the first picture we took. First, the grey should be lighter but not quite white yet. And second, the histogram should look like a spike entirely in Zone VI. We moved up one Zone in exposure, also called one FULL STOP among some photography buffs.
Forth Experiment: Leaving the f-stop and ISO values alone still, cut your shutter speed in half again. In my example, I'm moving my shutter from 50 to 25. That represents another full stop. I'm hoping for another change in the final exposure, from Zone VI to Zone VII. Take the picture. Observe the differences again in the picture captured and the histogram. Did we hit "white" yet? Is the spike entirely in Zone VII?
Just for fun, go up one more stop. You know, slow down your shutter, again cutting the value in half so the shutter stays open twice as long. Now take the picture. Is the histogram pegged against the right wall? Is the white now all blown out? You're 3 stops above the camera's initial decision.
Let's get really crazy and move a full 4 stops up from the original exposure and again take the picture. Is there any change at this point between this picture and the one before it? My guess is that there is not, but I can't see what you're seeing.
Okay, so far we've manipulated our exposure so we could move UP through the zones. We manually changed the exposure so that our white paper was recorded properly, rather than the feeble grey attempt our camera made on its own.
Fifth Experiment: Now we're going to repeat the above experiment, this time starting with the picture we took of the black paper and move the other way, down through the Zones while photographing the black paper. Begin by writing down the shutter speed, f-stop and ISO settings that the camera chose automatically when you took a picture of the black paper hanging on the wall.
Next, manually plug these values into the camera. If we take a picture of the black paper, we should get the same grey result because we are using the same exposure settings that the camera chose when it over-exposed the black paper and made it appear grey.
Now we're going to move down a full stop and check our results as we go. The goal is move the exposure down, one stop at a time, until the camera properly records black for us rather than the grey it wants to record.
To underexpose by one full stop, we need to speed up the shutter so it is open for 1/2 as long as the camera decided on before. If the number you wrote down is 15 for example, we need to plug 30 into the shutter speed setting manually. In other words, from a 15th of a second to a 30th of a second. Less time for light to come in, darker exposure. One full stop. If the shutter was 1/2 a second, plug in 1/4 second. You get the idea. Now point at the black paper on the wall and take the shot.
We should observe a darker grey, which is Zone IV. The histogram should confirm that if we did everything correctly.
Speed up the shutter again for another full stop. You know, double the shutter number. Take the picture and you should see Zone III represented this time, both color-wise and histogram-wise. Did it work?
If you want to go down another stop, have at it. Feeling really crazy? Try dropping down a forth stop from the original exposure. You are living on the edge.
Taking This To The Real World
Okay, now you know how the camera attempts to expose for Zone V. And you know how to override that to get the zone you want.
The next feature on your camera that you need to know how to manipulate is the metering mode. So far, we haven't had to worry about it because we've been filling up the entire viewfinder with a piece of paper.
Your camera should have multiple metering modes. One of those modes will take the entire scene into account as it attempts to figure out what "average" should be. Another mode should look at a block in the middle of the scene, maybe 50% or 60% of the total image. Yet another metering mode might be a fancier version of the middle, giving more statistical "weight" to the middle and less "weight" to the outer edges.
In particular, we need to put our cameras into a "spot meter" mode, at least that's what Canon calls it. I'm sure Nikon people will correctly inform me in the comments below what the equivalent name is for Nikon cameras. Whatever it's called, the goal of this next exercise is to have the camera evaluate only the smallest possible center spot as it attempts to calculate the proper exposure (8% of the total scene in my Canon camera for example.)
Here's what we're going to do:
- Put the camera in manual mode
- set the camera metering to "spot meter" mode
- point the camera towards a bright highlighted location in the scene
- adjust the f-stop, ISO, and shutter until you get a normal exposure.
Before you snap the picture, think about what we learned up to this point.
- The camera is now telling you that the settings you've dialed in are going to make that highlighted spot look just like Zone V. We now know that it will be under exposed and need to adjust our exposure up accordingly
- If it is a light color such as tan, amber, or yellow, then the proper exposure for that spot is not Zone V, it should be exposed for Zone VI.
- If you spot metered on something white, then you know it should be exposed as Zone VII.
- You need to move the exposure up one or two full stops accordingly from what that meter is telling you about the highlight that you're staring at.
Now with your new exposure settings plugged in, recompose the scene and take a test shot of that entire scene to verify.
Having trouble finding a bright white item in your scene large enough to spot meter? Find a sufficiently large dark area, something that should be in Zone III or Zone IV. Spot meter that location. Knowing that the camera is over-exposing that dark spot, you can now darken it down a full stop or two accordingly. Recompose your view and take a test shot of the scene to verify that your eye was correct.
In Summary
Is your head spinning yet? That was a lot to digest. Go back through it again if you need to.
When we switched from automatic to manual mode on the camera, the only variable I had you change was the shutter speed. The other two variables, f-stop and ISO, along with shutter speed make up what is known as the "exposure triangle." All three are interdependent on each other.
You've now been exposed (pun intended) to Ansel Adam's Zone System.
And in all fairness, Ansel did more work after snapping the picture. When he was developing his images in his darkroom, he mastered techniques like dodging and burning to make minor exposure corrections to the final image. We can do the same thing digitally in Photoshop (a future blog post.)
Feeling brave and adventurous? Go back through the experiments above leaving the shutter speed consistent and play with the f-stop to move from one Zone to the other. Then repeat changing zones by changing the ISO.
In a future blog post, I will explain the exposure triangle in much greater detail.
Having trouble working through these pictures and obtaining the desired results? I want to help. Reply to this post below or send me an email. Love to help you out.
