Image capturing device and auto-focus method for the same

An image capturing device comprising:

• a taking lens;
• an image sensor configured for converting light transmitted through the taking lens into electrical signals;
• a driving device for moving the taking lens;
• an input device used for selecting a plurality of focus areas in a photographing area formed by the taking lens before an image of the photographing area is captured;
• and
• an auto-focus system comprising:
• an auto-focus module capable of controlling the image capturing device to focus on each focus area alone to obtain a plurality of in-focus positions of the taking lens corresponding to the plurality of focus areas;
• a calculating module for calculating a plurality of distances between a predetermined starting position of the taking lens and the plurality of in-focus positions of the taking lens, and averaging the plurality of distances to obtain an average distance;
• a driving module for controlling the driving device to move the taking lens the average distance to arrive at an in-focus position of the taking lens corresponding to the plurality of focus areas.