| 摘要 |
<p>Autofocus (AF) assist lighting can be useful as a camera rangefinder in low light conditions. When ambient light conditions are inadequate for determining camera-to-subject distance using through-the-lens autofocus (TTL-AF) procedures, the AF assist light is used to attempt to raise the light level enough that the camera-to-subject distance can be determined using TTL-AF. If a camera-to-subject distance is not determined when the AF assist light is used, a camera-to-subject distance based on tabulated values is determined using an empirical model of AF assist luminance increment versus distance. If a camera-to-subject distance can be determined using TTL-AF when the AF assist light is used, but the lighting conditions are inadequate, the camera-to-subject distance used for capturing an image is a weighted combination of the TTL-AF camera-to-subject distance and a camera-to-subject distance based on a set of tabulated values determined using an empirical model of AF assist luminance increment versus distance.</p> |
