No matter what mode you are shooting in it is helpful to have an understanding of what the Exposure Value is and what Metering Modes your camera has, and what they do. When you understand how these two work together, you will be able to select more appropriate exposure settings, faster. With the advent of digital cameras, and the ability to immediately review your shots, the importance of understanding these two concepts has diminished. The LCD easily can be used as your light meter, simply take test shots, and adjust your exposure according to what you see on your LCD back. Nonetheless, understanding both the Exposure Value, or EV, and your camera’s Metering Modes is an invaluable asset to any serious photographer. Understanding how to read you EV meter and how the Metering Mode you are using is detecting light will give you the ability to more quickly and accurately choose an exposure setting which is closer to the proper exposure and bracket from there.

How Exposure Value And Metering Mode Work Together
The Exposure Value is a single value on a scale which determines the light exposure of your image, taking into account the ISO, Shutter Speed, and Aperture Size. It basically tells you how light or dark your image is, allowing you to adjust the exposure accordingly, prior to taking your shot. Now, your camera determines what is too light, too dark, and just right by making calculations based on how much light is entering your lens. This is where the Metering Mode comes in. The several Metering Modes each instruct your camera to read the light entering the lens in different manners. Generally speaking, this means that your camera may only read the light coming from a single spot in the image, or by taking the average of light in a larger space. If this is confusing, I will attempt to make it clearer below, so read on.

What’s EV
The EV is your Exposure Value. The value is a result of three settings, either chosen by you or by the camera: ISO, Shutter Speed, Aperture Size. What these settings do and what the EV represent is the amount of light in your image; or simply, the exposure; or simplest, whether your image is too bright or too dark.

Follow The EV
When you look at your LCD screen or through your viewfinder you will see a scale number from -2 through + 2 with 0 right in the middle. The 0 represents the appropriate exposure that the camera has determined. There should also be an indicator along the scale, which indicates what your actual exposure is, relative to the 0. If your current exposure is off the scale, there should be an indicator such as an arrow at the end of the scale, which indicates that your exposure is off the scale. The general idea is to match your actual exposure with the exposure which the camera has determined, i.e., 0.

Adjusting The EV
Adjusting the EV is the same as adjusting the exposure. Remember that the exposure is the result of the ISO, Shutter Speed, and Aperture Size; so it follows that adjusting either of those three will change your exposure and EV. As a matter of fact, your EV will change in tandem with the amount you change either the ISO, Shutter Speed, or Aperture Size.

So, where your camera’s EV indicator shows that your exposure is too dark you can increase the ISO, decrease the Shutter Speed, or open the Aperture Size.

On the other hand, where your camera’s EV indicator shows that your exposure is too bright you can decrease the ISO, increase the Shutter Speed, or close the Aperture Size.

Of course, whether too bright or too bright, which setting or settings you change depends on the circumstances and your own preferences.

Metering Modes and EV
After reading about the Exposure Value and how the 0 represents what your camera thinks is the correct exposure, you might be wondering how the camera determines what the correct exposure is. That where the Metering Mode comes in. The Metering Mode used does not affect how the final image comes out, rather the Metering Mode is the method by which your calculates the proper exposure.

On a basic level, the camera determines the proper EV by sensing the amount of light coming through the lens. Based on what the camera senses, it makes some calculations to determine what would work best. The Metering Mode chosen will change how your camera sensing the light and how it calculates the correct exposure.

Most cameras today come with three Metering Modes, spot, center-weight, and some auto mode.

Spot Metering Mode
The Spot Metering Mode collects bases its calculations on a very small area of your view, a spot. At its most basic, the spot is in the center. Some more advanced cameras allow you to choose among several spots. Use this mode to determine the proper exposure by placing the spot on an area and the EV will tell you the proper exposure for that spot.

Center-Weighted Metering Mode
The Center-Weight Metering Mode collects light from the entire view, but it places greater importance on the center of the view, an area larger than in Spot Metering.

Auto Mode
I actually heard of the name Auto Metering Mode but that’s what I call it, it is called by other names such as multi-pattern, or matrix, or the like. This mode, like Center-Weight Metering takes light from the entire view, but makes more complex calculations, rather than just favoring the center.

Which Mode
In the end, it really doesn’t matter which Metering Mode you choose. The important thing with Metering Modes is to know what they do and which one you are using.

Letting The Camera Select The Exposure
It only really matters if you don’t know how to do exposure lock or exposure compensation. If you don’t know how to lock the exposure with your camera or compensate, then you are leaving your exposure to the mercy of your camera’s processor. In most case the cameras produced today can make great guesses, resulting in great exposures, but sometimes the camera can get confused. When letting your camera choose the proper exposure, your choice of Metering Mode can greatly change what your capture.

Generally, the Auto Mode, or Multi-Pattern Metering Mode shoot be selected. It is a great all around Metering Mode that can make great guesses, based on the entire scene. Works particularly well in evenly lit scenes.

The other setting which should be generally used is the Center-Weight Metering Mode. This works most of the time, since most of the time you will want the center of the scene properly exposed. But, particularly useful when the scene is unevenly lit, where the center is much brighter or darker than the rest of the scene and that’s what you want properly exposed.

Spot Metering Mode should probably not be used so much if you don’t know how to lock the exposure or adjust the exposure. Since the Spot Metering Mode only reads light from a spot, your exposure can easily be based on a small shadow or bright highlight which does not represent the lighting of the entire scene.

Selecting Your Own Exposure
If you know how to select your own exposure, whether you shoot in full manual mode, or you are adept at exposure lock and exposure compensation, than the Metering Mode selected is not all too significant. You just need to understand how the Metering Mode you choose works, and make it work for you.

For example, I shoot in manual and I typically use the Spot Metering Mode. Even though the Spot Metering Mode only takes a light sampling from a small area, I find it most useful. I will often spot meter the darkest area in the scene, the lightest area in the scene, and the subject and make a guess as to the right exposure, based on those readings.

Reading The Light
So that’s your Exposure Value and Metering Modes. Based on what Metering Mode you choose, your camera will suggest an appropriate exposure. The Exposure Value is derived from the ISO, Shutter Speed, and Aperture Size and represents the image exposure. On the EV scale the 0 is the camera’s recommended exposure and the scale displays what your exposure is in relation.

Understanding how your camera reads the light is the starting point to a properly exposed image. If you can read and understand your EV scale, and its relationship with the Metering Mode, you can quickly and accurately choose the proper ISO, Shutter Speed, and Aperture Size. When in doubt, the EV scale is a good starting point to getting the right exposure.