A Short Course Book
Using Your Digital Camera
A Guide To Great Photographs

How To Override Automatic Exposure

 
Underexposing by 2 stops kept the background dark while correctly exposing the spotlit subjects.
 
 
Click to explore exposure compensation.
 
 
The universally recognized icon for exposure compensation.
 
 
Pressing the shutter button halfway down locks exposure and pressing it all the way down takes the picture.
 
 
Click to explore exposure lock.
 
 
If you took the picture without first locking exposure, it would be too dark because the background influenced the exposure.
 
 
A common icon for AE Lock buttons.
 
 
Click to explore autoexposure bracketing.
 
 
Some cameras let you select the number of shots and the exposure increment between each. Here the scale has no bracketing (top) followed by settings for one, two, and three stops difference between exposures.
 
 
The standard icon for auto exposure bracketing.
Most digital cameras provide ways to override the automatic exposure system to get the exposure you want. The most common choices are exposure compensation, exposure lock, or autoexposure bracketing.

Exposure Compensation

Exposure compensation lets you lighten or darken the photograph that the camera would produce if operated automatically. To lighten a picture, you increase the exposure; to darken one, you decrease the exposure. The amount you increase or decrease the exposure is specified in "stops". For example, to increase the exposure 1 stop, you specify +1 to open the aperture or slow down the shutter speed. It's easy to use exposure compensation because you can preview your changes on the monitor and reshoot if warranted.

When you adjust exposure compensation you can do so in full stops and even finer increments—usually one-third (shown here) or one-half stops. On most cameras you will see a scale displayed when you use this command. The "0" indicates the exposure suggested by the camera. As you adjust the exposure toward the plus (+) side of the scale the image gets lighter. As you adjust it toward the minus (-) side it gets darker. Here you see the results as it's adjusted from +2 (left) to -2 (right). The effect of the changes on the image are dramatic.
 
Use + exposure compensation when the subject is bright and when it's dark.

Auto Exposure Lock (AE Lock)

You can adjust exposures with a procedure called autoexposure lock (AE Lock) that works much like focus lock. You point the camera so the part of the scene you want to base the exposure on is metered (spot metering works best) and press the shutter button halfway down to calculate the exposure and focus and lock them in. While continuing to hold down the shutter button, you recompose and shoot the picture using the locked in settings. Some cameras also have an AE Lock function that lets you lock exposure independently of focus. The only real difference is that you lock exposure by pressing the AE Lock button instead of the shutter button and it remains locked until you take the picture. Focus is then determined when you take the picture, even if you have changed your position.

Top. Point the camera so you are metering the area on which you want to base the exposure. Press the shutter button halfway down to lock exposure (and focus).

Bottom. Without releasing the shutter button, compose the image the way you want it and press the shutter button the rest of the way down to take the photo.
 
HOW TO: USING EXPOSURE LOCK

1. Point the camera so the subject that you want to lock exposure on is in the focus area in the center of the viewfinder.
2. Press the shutter button down halfway and hold it there to lock in the exposure.
3. Without releasing the shutter button, recompose the scene and press the shutter button the rest of the way to take the picture.

Auto Exposure Bracketing (AEB)

When you want to be absolutely certain you have the best exposure, autoexposure bracketing (AEB) mode takes a series of photos—each at a slightly different exposure. It's basically an automated form of exposure compensation. Some cameras let you specify both the number of exposures, usually 3 or 5 of them, and the change in exposure between each shot. Some cameras take all of the pictures with a single press of the shutter button. With others you have to press it once for each picture.

Bracketing gives you a series of images at different exposures.


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