Abstract: Disclosed are a focus detecting apparatus capable detection in various light illumination conditions and an image acquiring apparatus having the same. The focus detecting apparatus may include a mark disposed on a primary image plane. A pair of images of the mark is detected by a sensor, the distance between which images is used to determine the main wavelength of the light received from a subject. The main wavelength is used in determining the chromatic aberration correction by which the defocus amount may be adjusted.

Abstract: An image pick-up apparatus which is capable of increasing an AF area is provided. The image pick-up apparatus includes a photographing lens to focus light received from a subject, a main mirror that passes a portion of light passing through the photographing lens and that reflects the remaining portion of the light, an auto focus module to detect the state of focus the photographing lens and a sub-mirror having a plurality of reflective areas that reflect respectively divided portions of the light passing through the main mirror and that guide the divided light portions to the auto focus module.