(Photo by zev)

For many entry-level photographers, the term AE-L is relatively new. It can make the camera one value maintain an ideal exposure value, allowing you to change the composition at will! Let’s take a look at the usage of the AE-L button!


Camera’s Automatic Metering System

If you have read the previous article (using the camera’s automatic metering system), you will also know that there are roughly three types of metering systems built into the camera: matrix metering, center-weighted metering, and spot metering. In environments where the light and dark are very different, we may need to use center-weighted or spot metering if the subject is normally exposed, but if we have to move the central area away from the subject after the metering to recompose the picture, the system will perform re-metering (or the metering value before and after the composition has changed!). To make the previous metering obsolete, then, in this case, we need to use the AE-L button to lock the exposure value!

Several Settings of AE-L/AF-L Button

The MENU can adjust the following responses after pressing AE-L/AF-L:

  • AE/AF lock simultaneously
  • Lock only auto exposure
  • Lock only autofocus
  • Keep AE locked
  • Turn on autofocus
  • FV lock

Let us focus on the above exposure items (red):

Only lock the auto-exposure means that the exposure value will not change after pressing the button, but if you release the button once, the auto metering will resume.

Keep AE lock means that the exposure value will remain locked for some time after pressing the button (the viewfinder will display EL) until the user presses the AE-L button again to release it.

FV lock is not controlling exposure. It is used to control the flash output value, and its usage is similar to the metering system.

Application of AE-L Button

AE-L is also useful in shooting landscapes or portraits. Let us look at the following examples:

No locked exposure

Figure 1-Unlocked Exposure Value

Use AE-L to lock the exposure value

Figure 2-Locking exposure value with AE-L

Figure 1 above moves the camera to recompose the picture after focusing on the text. Because the photographer’s camera automatically locks focus and metering after pressing the shutter button halfway, the metering system conveniently uses the framed picture when focusing to determine the exposure value because of the ceiling and text. The relationship between brightness and exposure is insufficient after recomposing. The solution is to lock the metering by pressing AE-L when not focusing, and then focus and restore the composition. As shown in Figure 2, you can get the correct exposure, but not press the shutter to lock the metering halfway, so you don’t have to press AE-L (because the camera will automatically use the last frame for metering) unless you want the text to be exposed normally, you can meter the text and press AE-L to maintain exposure lock and recompose.

The same is true for outdoor portrait photography, you can first meter the model’s face and press AE-L to lock the metering, the exposure of the model’s face will be normal and not affected by the external environment, but this method overexposes the background. In fact, a better way is to use a reflector or a flash to fill the light.

Photo source: Tilo Driessen http://www.486word.com/new_page_162.htm

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Author: Alex Tam