Focusing information detecting device, focus detecting device and camera utilizing the same
AssigneeCanon Kabushiki Kaisha
InventorsMasaki Higashihara, Masato Ikeda
Life of this patent
Estimating the term…
Abstract
A focus detecting device for detecting images from different pupil areas on time-shared basis, and detecting the phase difference of the images from the different areas, thereby detecting the defocus amount, is described. The focus detecting device of this type is incapable of exact defocus amount detection, because of the influence of the relative movement between the object and the photographing optical system. The exact defocus amount can be determined by detecting images from a same pupil area on time-shared basis, determining the phase difference between such images and effecting correction corresponding to the phase difference between the images from the same pupil area.
Claims3
A focus detecting device provided with an image pickup portion, a focusing optical system, a pupil shape varying portion for time-sequentially dividing a light beam passing through said optical system into at least two different areas and projecting on said image pickup portion, and a calculation circuit for calculating the focus state of said optical system by converting optical images projected time-sequentially on said image pickup portion through said respective areas into image signals and detecting the phase difference of said image signals,
- wherein said calculation circuit includes a correction calculation portion for correcting the influence caused by the movement of the optical image resulting from a relative positional change between the object and a camera in the phase difference of two image signals formed through said different areas, utilizing the phase differences of three or more image signals, said calculation circuit is adapted to detect the phase difference of the two images formed through said different areas, after correction of the influence caused by the movement of the optical image resulting from the relative positional change between the object and the camera, and
- wherein said correction calculation portion has plural different calculation process modes and includes selecting means for selecting one of said plural modes according to the photographing condition.
Dependencies are inferred from the claim text.