Auto Exposure Lock

Sometimes we may want to take a series of photos with the same exposure parameters (i.e., aperture, shutter speed, sensitivity, and white balance). One possible situation is taking a sequence of photos and stitching them into a panorama or a 360 degree view. Fixing exposure parameters to certain values is not difficult because we can use manual exposure and preset white balance. However, there is a better way: the use of auto exposure lock, or AE Lock for short. This will lock aperture, shutter speed, sensitivity and white balance to the same setting until you unlock them.

Activating AE Lock

To activate AE Lock, follow the procedure below:

1. Set the camera to the P mode, A mode, S mode or M mode by holding the MODE button and turning the command dial at the same time.
2. Press the MENU button once to enter the first page of the SHOOTING MENU. You will see the following screen:
   
3. Use the down arrows of the multi-selector to enter the menu system. The first menu item is highlighted as shown in the left image below. Then, press the MENU button twice to enter the third page as shown in the right image below.

4. The first option Exposure Options is what we need. So, use the right arrow of the multi-selector to make a selection (below left). There are two options. The first one, AE Lock is what we need. Thus, use the right arrow to make a selection. Then, the three AE Lock options appear as shown in the right image below.

   The meaning of these options is shown below.

   Option	Meaning
   Off	Deactivate AE lock and restore normal exposure, sensitivity, and white balance.
   On	Activate AE lock. The exposure parameters used for the first photo taken after activating AE lock is used for all subsequent photos. The parameters include aperture, shutter speed, sensitivity, and white balance. Flash is disabled when AE lock is in effect.
   Reset	Change the "locked" exposure parameters. More precisely, after selecting Reset, the camera is still in the AE lock mode; but, the exposure parameters used for the first photo taken after selecting Reset is used for all subsequent photos. Hence, when you have to change exposure parameters in the middle of a sequence of AE lock shots, use Reset.

   To choose one of these options, press the down arrow of the multi-selector to highlight that option, followed by the right button to select it.

5. Once the above steps complete, press the MENU button twice to return to the shooting mode.

   Note that once this option is chosen, it will stay there even after turning off the camera. Therefore, you need to go through the above procedure again to reverse the setting..

When AE Lock is in effect, AE-L is shown in the upper edge of the monitor.