Digital camera and focus control method

A digital camera comprising:

• a taking lens which forms a subject image of a subject;
• a lens drive section which moves the taking lens along an optical axis;
• an imaging section which repeatedly takes the subject image formed by the taking lens at a predetermined time interval to output continuous image signals;
• a focus evaluation value calculation section which repeatedly calculates a focus evaluation value representing a degree of a focusing state of the taking lens with respect to the subject image, on the basis of the image signal output from the imaging section;
• a manual focus controller which controls the lens drive section to move the taking lens in response to a manual operation;
• a splitting optical system which splits a light path, having entered through the taking lens, into a plurality of light paths to form an image;
• a phase difference detection section which detects an amount of deviation between a plurality of optical images formed by the splitting optical system;
• a first auto focus controller which controls the lens drive section on the basis of the amount of deviation between said each optical image, detected by the phase difference detection section, to move the taking lens such that the subject image is focused on the imaging section;
• a focus evaluation value change detection section which detects a change in the focus evaluation value generated by the movement of the taking lens;
• a second auto focus controller which controls the lens drive section in accordance with the change in the focus evaluation value detected by the focus evaluation value change detection section to move the taking lens so as to be focused on the imaging section;
• and
• a focus mode selection section which selects at least one of an auto focus mode, a manual focus mode and a semi auto focus mode, the auto focus mode driving the lens drive section under the control of the first auto focus controller to move the taking lens to the focusing position, the manual focus mode driving the lens drive section under the control of the manual focus controller to move the taking lens by an manual operation, the semi auto focus mode automatically switching from the manual focus controller to the second auto focus controller when a predetermined change pattern in the focus evaluation value is detected by the focus evaluation value change detection section to move the taking lens to the focusing position.

A focus control method for a digital camera comprising:

• repeatedly taking a subject in a continuous manner at predetermined time interval by an imaging section and outputting a sequence of image signals;
• displaying a live image on the basis of the sequence of image signals taken by the imaging section to a monitor of the digital camera repeatedly calculating a focus evaluation value, representing a degree of a focusing state of a taking lens, on the basis of an image signal output from the imaging section;
• performing manual focusing for moving the taking lens in response to a manual;
• detecting a change in the focus evaluation value generated in accordance with the movement of the taking lens;
• and
• when a predetermined change pattern in the focus evaluation value is detected during manual focusing, performing one of a first focusing mode for continuing manual focusing and a second focusing mode for making transition to auto focusing in which the taking lens is automatically moved such that the focus evaluation value becomes a peak value in accordance with a predetermined selection by an user.