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Digital Photography Basics

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Special Shooting Modes

How to Choose a Shooting Mode

Photographers often refer to photos as exposures because a photo captures an instant when the sensor (or film) is exposed to light. Your digital camera contains a few standard shooting modes that enable you to control how light enters the camera and, thus, how your exposure will look.

How Exposure Works

When you press the shutter button to take a photo, a hole called the aperture at the base of the lens opens to let in light. The amount of light that reaches the sensor depends on:

Aperture size: The diameter of the hole
Shutter speed: The amount of time the hole stays open

In most situations, more than one combination of aperture and shutter speed work together to create the right exposure. For example, a large aperture that's open for a very short time will let in the same amount of light as a small aperture left open for a long time.

Overexposure and Underexposure

If the combination of aperture size and shutter speed for a particular picture lets in either too much or too little light, your photo will be either overexposed or underexposed.

Overexposure: This occurs when too much light enters the lens. Overexposed photos look washed out and lack detail in the light areas.
Underexposure: This occurs when not enough light enters the lens. Underexposed photos look dark and lack detail in the dark areas.

Light Meters

A digital camera contains a built-in light meter, a device that allows the camera to calculate which aperture size and shutter speed to use in order to expose the photo properly. Through your selection of a shooting mode, you can choose to defer to the light meter’s choices entirely or control the settings on your own. The shooting mode you choose should depend on the subject matter of your shot.

Automatic and Program Modes

In both the automatic and program shooting modes, the camera automatically controls the aperture size and shutter speed. The two modes differ only in how much control they give you over the camera’s other settings:

Automatic mode: The camera controls all its own settings—you just frame the shot and press the shutter button to take it. Automatic mode is usually represented on the camera dial with the word auto.
Program mode: The camera sets the aperture and shutter speed automatically, but you can still control other options, such as whether to use the flash. Program mode is usually represented with a P on the camera dial.

Aperture Priority Mode

In aperture priority mode (usually represented by an A or Av on your camera dial), you select the aperture setting before you take a picture, and the camera chooses the shutter speed that will provide the optimum amount of light for that setting.

Aperture Settings

The size of the aperture is represented by settings, called f-stops, which usually range from f/2.8 (largest aperture size) to f/22 (smallest aperture size). As the f-stop number increases, the size of the aperture opening decreases, allowing less light to pass through the lens.

Aperture and Depth of Field

Besides controlling the amount of light that passes through the lens, the aperture setting affects the depth of field, or the portion of the photograph that appears in focus.

Smaller aperture settings (higher f-stop numbers): Yield a greater depth of field
Higher aperture settings (lower f-stop numbers): Yield a shallower depth of field

In both of the photos above, the lens is focused on the hand holding the mug. But the depth of field is shallower in the right-hand photo because the photographer used a larger aperture. As a result, the subject in the background of the right-hand photo appears out of focus.

Why Choose Aperture Priority Mode?

Use aperture priority mode when you care about the depth of field in a photo. For instance, when shooting a vast landscape, you might choose a smaller aperture (higher f-stop number) so objects in the foreground and in the distance appear in focus. Or you might use a larger aperture (lower f-stop number) to emphasize a particular object in the foreground, such as a person’s face, and blur the background intentionally.

Shutter Priority Mode

In shutter priority mode (usually represented by an S or a Tv on the camera dial), you set the shutter speed before you take a photo, and the camera chooses an aperture that will provide the optimum amount of light required to expose the photograph.

Shutter Speed Settings

Shutter speed is measured in fractions of a second. A setting of 1/30 means that the shutter will be open for one-thirtieth of a second. Shutter speeds can range from 30 seconds to 1/8000 of a second or shorter. Most cameras also include a setting called bulb that lets you keep the shutter open for as long as you like.

Shutter Speed and Movement

Shutter speed affects how a camera captures movement:

Faster shutter speeds: Capture fast-moving objects crisply and clearly. The shutter opens and closes so fast that the object covers almost no distance in that time.
Slower shutter speeds: Blur moving objects. The shutter is open long enough that it captures the moving object as it moves through space.

In the images above, the shutter speed used in the right-hand photo was not fast enough to capture a sharp image of a moving subject.

Why Choose Shutter Priority Mode?

Choose shutter priority mode when you're dealing with moving objects and want to create a particular effect. For instance, if you want to freeze an object that’s moving quickly, such as a child on a swing, or if you want to blur objects in motion, such as a stream of headlights on a highway, intentionally for effect.

Manual Mode

Manual mode allows you to select both aperture size and shutter speed. You can still refer to the camera’s built-in light meter to guide your choices, but you’ll be able to override the camera’s suggestion if you’d like.

How to Use a Light Meter

When you press the shutter button halfway down in manual mode, you activate the light meter. The light meter evaluates the aperture and shutter speed settings and tells you whether the combination you’ve selected will let in the right amount of light. It usually indicates its assessment, called a light reading, on a scale that rates the current light in terms of too much, too little, or just right. The light reading appears on the LCD screen or in the camera’s viewfinder, the small hole you look through to frame your photos.

If the light meter indicates too much light: Choose a smaller aperture or shorter shutter speed.
If the light meter indicates too little light: Choose a larger aperture or longer shutter speed.
If the light meter indicates just the right amount of light: Take your shot or adjust the shutter and/or aperture to get the exposure you prefer.

Why Choose Manual Mode?

The main reason to use manual mode is to ensure that you can override the camera’s light readings to achieve a certain effect, such as blurring an object in motion or taking a long exposure at night. Manual mode also allows you to change either the shutter speed or the aperture on the fly, an action that can require several steps in other modes. Many photographers use the camera’s light meter for reference but then take several shots with various shutter speed and aperture combinations to increase the likelihood of getting a perfect exposure. Since digital photos cost nothing to take, you can shoot dozens of shots of one scene and pick the best exposure later.

Acknowledgments & Disclaimer