Metering tonalities
Wouldn’t it be great if everything in nature reflected 18% of the light? That sure would make exposures easy. It would also make the world (and our pictures) boring.
Fortunately for all of us, nature is wide ranging in shape, color, and light.
Unfortunately, for just us photographers, our cameras can’t record the entire range of light nature holds. That’s ok. If good photography wasn’t a challenge, that too would be boring.
Many things in nature reflect 18% of the light—also referred to as medium toned. And when you learn to recognize this tone, you can use it to set your exposures. But many other things in nature reflect more than or less than 18% of the light. In other words, they are lighter or darker than medium. Learning to recognize tonalities in nature is just one more step in mastering exposure. And when you do learn to recognize different tonalities, you’ll be able to use them to set exposures.
It should be obvious that some objects reflect more light than others do. We see this every day. White flowers are lighter than red flowers. White reflects more light than red. A snow bank reflects more light than a bison. We can use our in-camera light meters of see just how bright objects are in relation to each other.
Since many things in nature are of medium tonality (18% reflectance), it’s always a good idea to start there. Here are a few objects that are generally medium toned:
- Tree bark
- A cloudless northern sky at about 45 degrees
- Green grass is generally medium, though this depends on the season
- Green leaves
- Brick Red
- Gray rocks
This means that if you point your meter at one of these medium toned objects and zero the meter, the medium toned object is rendered as medium on film. Just what we want.
The real cool part about all this is that if there are also objects in the scene that are not medium (either lighter or darker), they too are rendered the proper tone—as long as you based your reading off of the medium-toned object.
The corollary to this is that if you get any tonality right, the rest will come out right as well. This is true as long as everything is in the same light. If you know the tonality of an object, meter on it, and set the camera to render that tonality. The object will come out just the way you wanted it and so will everything else.
Let’s look at that snow bank example from the last lesson Back to basics Meters. Snow is typically 1.5 to 2 stops lighter than medium. If you point your meter at a snow bank and change the setting until the meter indicates about +1.5 to +2, the white snow bank will come out white.
Remember that slide film has a typical latitude range of plus and minus two stops from white with some detail, to black with some detail. Keeping that in mind, if we meter something and set the meter to medium, the object comes out medium—we already know this.
If we change setting so that the meter indicates +1, the subject will come out one stop lighter than medium—a light tonality. If we change setting so that the meter reads +2, the subject will come out nearly white, which is just about the limit of slide film as well as digital sensors.
On the other side of that, if the meter shows -1, the subject will come out 1 stop darker than medium—a dark tonality. A -2 stop reading is very dark to black, which is the other limit of slide film. For digital sensors, -2 is still dark, but you have more range in the darks with digital cameras than you do with slide film.
The catch here is that the subject will come out as the meter indicates. If you zero the meter, the subject will come out medium, regardless whether it’s medium or not. (That’s why snow comes out looking grey so often)
If you set the meter to read +1, the subject will come out one stop lighter than medium, whether it is or not.
If a subject is in reality lighter than medium and you set your meter to read lighter than medium, the subject will come out lighter than medium—not lighter than it actually is. Re-read that last sentence, this is important. And it really is that simple. Meter a subject and set the controls on your camera until the meter indicates the desired tonality. The subject will come out the tonality you set it for. If the subject is a stop lighter than medium and you want it to look like it does in reality, set the meter for one stop lighter than medium.
For example, if you know a subject, say a yellow flower, reflects more than 18% of light, say one more stop of light, you can meter that subject, set the meter to read +1, and the subject will come out one stop lighter than medium—just like it really is.
To help get you started in this, here’s a short list of some other tonalities in nature.
- Yellow leaves (fall color): +1
- Yellow flowers (daffodils, etc.): +1
- Green grass: -2/3 to medium (0) depending on the season
- Dry grass: +2/3 to +1
- Evergreen trees: -2/3
- Snow: +1 ½ to +2
- Reds: medium to –1 depending on how deep the red is Pink: is light red, +1
- Desert sand: generally +1
- Palm of your hand: +1
- Sandstone (arches, rock formations, etc): +2/3 to +1
And remember, if you get one of these tonalities right, the rest will fall into place—as long as they’re all in the same light. This won’t work if a part of the scene is in sun and a part in shade.
Here are a couple of illuminating exercises you can try.
Exercise 1:
Put your camera in the manual exposure mode and select spot-metering as your metering method. Spot meter something you think is medium and zero the meter. Now, without changing any settings move the camera around and place the spot meter on different objects. Note which ones are also medium and which are lighter and darker than medium. This will help you get used to the idea that different objects reflect different amounts of light.
Exercise 2:
Gather something white, something black and something medium gray. I suggest using white and black mat board and a Kodak gray card. Now photograph each of these individually in the same light. Fill the frame and simply zero the meter. You can do this with either film or with a digital camera. Look at the results. What happened? Why?