A camera’s built-in light meter measures the level of incident light and adjusts aperture, shutter speed, and ISO based on that. Your exposure mode setting determines how your camera will work with the light levels that it measures. Depending on the mode, the camera will either adjustments fully automatically, or leave you a certain amount of control over a photo’s final tonality. Meanwhile in manual mode, the meter has no effect on the exposure settings at all. What exposure modes do cameras offer and how are they useful? We’ll be answering these questions in today’s article.

Exposure Modes

Your choice of exposure mode determines how much of the decision on exposure settings (aperture, shutter, ISO) is left to the camera logic. Manual exposure mode is the only one where you have full control over all exposure settings. In all the rest, some or all exposure settings are set based on an exposure analysis performed by the camera logic.

Generally when starting out as a photographer, you can’t tell what settings a certain scene demands or what aperture/shutter/ISO will best fit your goals. So the automatic modes are for that stage of your progress. Over time—and with practice—you’ll discover the links among the three exposure parameters, get a feel for them, and learn the demands of various light situations.

That’s the time to stop using automatic modes and—most likely—start using the semi-automatic (creative) modes. In the end you’ll find that the automated systems are so out of touch with your creative goals that you’ll switch to manual mode.

Automatic Modes

The most basic automatic mode is full automatic mode. It’s usually represented by a green frame symbol. This mode decides absolutely everything for you. It evaluates the data from the meter and sets the aperture, shutter, and ISO for you. It also normally decides for you on whether or not to use the flash—although this is the one thing you can turn off in some camera’s automatic modes.

You have more control in the program modes, where you can set an ISO level, and if you have the feeling that your camera picked the exposure level incorrectly, you can change your exposure settings.

In this mode, some cameras also let you modify the program. You can for example make the camera use different aperture or time settings than the ones it picked. But the camera will still keep watch over your exposure values. I would recommend program modes for beginners with photographic ambitions. Program modes are also ideal when you’re using a borrowed camera that you’re not familiar with.

Scene Modes

With scene modes, you can have greater creative control without needing to intimately know the relationships among exposure values and their impact on how the photo looks. Just tell the camera what type of scene you’re photographing, and the camera automatically sets the exposure values and other values that best fit it.

The basic scene modes include landscape, portrait, sports, night portrait, snow, etc. Until you master exposure principles, scene modes can be a better choice that full automatic for obtaining high-quality photos.

For the last few years, many cameras have offered Intelligent Auto mode. In this mode the camera tries to recognize your subject and environment type and choose a scene mode based on that. I’m not sure how successful today’s cameras are in that regard… for now I’d still recommend picking a scene mode directly yourself.

Semi-automatic (Program) Mode

Semi-automatic (program) mode lets you choose one or more exposure values to express your creative intentions. It then sets the remaining values to make sure you get the correct exposure. It offers aperture priority and shutter priority.

In aperture priority, you choose an aperture setting, and the camera automatically adjusts the shutter speed. In shutter priority, you choose a shutter speed, and the camera picks the aperture accordingly. If you also set the ISO sensitivity to automatic, the camera will change the ISO for you based on light levels.

Program mode, and especially aperture priority, is what sees the most use in everyday photographic practice. You have full creative control and meanwhile your camera is making sure that you’re getting a correct exposure.

If you’re in bad light conditions that leave your built-in meter confused, then you can fix the exposure. The classic example is pictures against very bright or dark backgrounds, where the meter tries to achieve a middle-gray exposure. That makes it underexpose bright scenes and overexpose dark scenes.

Manual Mode

In manual mode, you have full control over exposure. You control all exposure settings yourself—the camera’s automated systems don’t intervene. But the light meter remains active, and you can go by its suggestions—or completely ignore them. Manual mode is best used in combination with an external meter that can precisely measure incident light.

Manual mode is most useful in three situations:

• When taking pictures in stable light conditions. You measure exposure once, set the exposure settings once, and all your pictures have consistent exposure. A good example of this is taking pictures in an artificially lighted interior.
• You’ll also want to consider manual mode in very dark and very light Manual mode helps you preserve the atmosphere of dark night in a night shot. In a semi-automatic mode, you can easily end up making a night scene look like high noon.
• You’ll also want to switch into manual mode when using studio flashes. In that situation your camera’s built-in meter is useless, since it can’t measure the light sent out by a studio flash. Also, photography using a studio flash works completely differently than photography using natural light. When working with natural, constant light, you adapt your exposure settings to that light to get the exposure you want. When working with studio flashes, you choose the exposure settings that fit your goals, and control the exposure by controlling the flash strength.

Exposure Lock

Use your camera’s exposure lock to set up exposure in a different part of a scene than the part you want to photograph. This is useful for situations like taking portrait photos against the light. You can set center-weighted metering so that your portrait is more than a silhouette—with this kind of metering, your camera’s meter emphasizes the center area of the sensor.

But that will give you center composition, which probably isn’t what you want. To avoid that, you can expose based on center composition, lock the exposure, and recompose the scene. Only after all that do you take the shot.

Another classic use case for exposure lock is when you’re taking a picture of the sky where the sun is in the shot. You need to set up exposure in a sunless part of the sky, because the sun is so bright that your picture would otherwise be underexposed. Here, too, exposure lock is good… although just switching into manual mode and setting up exposure there would be even better.

Modes by Genre

There are so many exposure options out there for your photography, from fully automatic, to program mode, to manual mode. Experienced photographers tend to be big fans of aperture priority, which makes it easy for them to express themselves while still making sure they’ve got a correct exposure.

Meanwhile in constant light conditions, you’ll get the most precise, consistent results using manual mode. For reportage you’ll want to use a program mode or a scene mode. But scene modes, like full automatic, are usually for beginners, since they leave no control over the final look of photos.