Various embodiments of the invention relate to a focus detecting apparatus.
As digital photographing apparatuses, such as digital cameras, camcorders, or the like, have been miniaturized and as technology relating to a battery, or the like, has been developed, digital photographing apparatuses can be easily carried. Thus, an image can be easily captured anywhere. In addition, digital photographing apparatuses provide a wide variety of functions that enable non-professionals to capture a good quality image.
In order to capture a good quality image of a subject, light has to be sufficiently irradiated onto the subject. When light is not sufficiently irradiated onto a subject, it is not easy to focus on the subject and a captured image is dark, and thus it is not easy to recognize the photographed subject. Thus, a lighting device for lighting a subject may be embedded in a digital photographing apparatus or may be separably installed on the digital photographing apparatus as occasion demands.
It is required that a subject be precisely focused on in order to capture a clear still image or a clear moving picture image by using a digital photographing apparatus, such as a camera, a camcorder, or the like. Examples of autofocusing (AF) methods include a contrast AF method and a phase difference AF method.
In the contrast AF method, a photographing operation is performed when a position of a focus lens is changed, a contrast value is obtained from an image signal generated by an image capturing sensor, and the focus lens is driven to a position at which the contrast value is a peak.
In the phase difference AF method, an image capturing sensor and an additional sensing device are disposed, and a focus position is detected from a phase difference in beams of light irradiated onto the sensing device.