70Reference—ExposureAutoexposure LockWhen center-weighted metering is used, an area in the center of the frame isassigned the greatest weight when determining exposure. Similarly, when spotmetering is used, exposure is based upon lighting conditions in the selected fo-cus area. If the subject is not in the metered area when the picture is taken,exposure will be based on lighting conditions in the background, and the mainsub ject may be under- or over-exposed. To prevent this, use autoexposure lock:1 Select exposure mode P, S, or A and choose cen-ter-weighted or spot metering (exposure lockhas no effect in exposure mode M). If us ing cen-ter-weighted me tering, select the center focusarea with the multi selector ( 53).2 Position the subject in the selected focus area and press the shutter-re-lease button halfway. With the shutter-release button pressed halfway andthe subject po si tioned in the fo cus area, press the AE-L/AF-L button to lockexposure (and focus, except in man u al focus mode). Confi rm that the in-focus in di ca tor (●) appears in the viewfi nder.While expo sure lock is in effect, an AE-L indicator will appear in the view-fi nder.3 Keeping the AE-L/AF-L but ton pressed, re com -pose the photo graph and shoot.
