Canon Kabushiki Kaisha

Yusuke Ohmura

Keiji Ohtaka

Shuusuke Tobita

A surface of a base material of a Fresnel lens has a central area having circular zones arranged therein and an outer area located on the outer side of the central area and having circular-arc zones arranged therein. The pitch of zones in a boundary area between the central area and the outer area and where the zone shape changes is smaller than a basic pitch which is the pitch of the circular and circular-arc zones in the central area and the outer area.

Fresnel lens and injection mold

An image-taking apparatus is disclosed that includes an image-pickup portion having a plurality of image-pickup regions, and a plurality of image-forming portions respectively corresponding to the plurality of image-pickup regions. The plurality of image-forming portions of the image-taking apparatus include a combination of image-forming portions that form object images on the corresponding image-pickup regions, by using light of mutually different wavelength regions. The image-forming portions constituting the combination have mutually different F numbers or mutually different apertures diameters of stops.

Image-taking apparatus

Disclosed is a focus detecting apparatus which is capable of enlarging a focus detection region and of enhancing focus detection precision. The focus detecting apparatus includes a secondary image forming optical system for forming a plurality of light, quantity distributions related to an object image from light beams passed through different pupil regions of an objective lens, and a photoelectric transducer having a plurality of pixel lines each having a plurality of pixels aligned in a predetermined direction, each of the plurality of light quantity distributions being formed on a corresponding pixel lines of the plurality of pixel lines. The secondary image forming optical system includes a deflecting member for deflecting at least one of the plurality of light quantity distributions in a direction perpendicular to the predetermined direction, and a correcting member for correcting displacement of an image formation position in the deflection direction of the deflecting member due to wavelength dependency.

Focus detecting apparatus

In the microlens array, a plurality of microlenses are formed with an irregularity or probability-distributed regularity so as to differ from a hypothetical base pattern, the hypothetical base pattern having apexes of hypothetical microlenses each spaced apart from every adjacent microlens thereof by an equal distance L. All the apex positions of the microlenses lie within circles each centered on an apex position in said hypothetical base pattern and having a radius equal to or smaller than 0.3L, or meet a condition: 0.4L &lE;P &lE;1.6L. In this way, a microlens array with bright and clean viewing characteristics and a high reproducibility of a shape of each microlens is provided.

Microlens array, optical apparatus, single lens reflex camera and optical finder

A focus detecting device for detecting a focusing state of an objective lens includes a field lens disposed adjacent to a prescribed image forming plane of the objective lens and having lens surfaces which differ in shape from each other correspondingly with a plurality of focus detecting areas, a reimaging lens disposed behind the field lens and having a pair of lens parts for forming a pair of light distributions for each of different pupils of the objective lens, and a light receiving sensor arranged to receive the pair of light distributions so as to detect the focusing state of the objective lens, wherein a first area of the field lens has a first field lens part having an optical axis which coincides with an optical axis of the objective lens, and a second area of the field lens which differs from the first area has a second field lens part having an optical axis which does not coincide with the optical axis of the first field lens part. The focus detecting device is thus compactly arranged and is capable of highly accurately making focus detection for a plurality of focus detecting areas.

Focus detecting device

A focus detecting device of the kind using an area sensor which has a plurality of focus detecting areas necessitates setting a correction value for every one of the focus detecting areas and storing all the correction values thus obtained, whereas, according to the invention, the correction value for each of the focus detecting areas of the area sensor is obtained by an arithmetic operation using, as variables, two parameters indicative of the position of the area, so that a focus detecting device can be arranged to obviate the necessity of storing all the correction values for the respective focus detecting areas.

A viewfinder system adapted for a single-lens reflex camera includes an optical system which guides light from an object to a viewer, a display part which displays information in a visual field of the optical system, a light combining member which is disposed in an optical path of the optical system and combines the light from the object with the information displayed by the display part, the light combining member having spectral transmission characteristics which differ with angles of incidence of light, and a correction member for keeping a spectral transmission characteristic of the entirety of the optical system substantially constant irrespectively of the angles of incidence of light on the light combining member.

Viewfinder system and single-lens reflex camera having the same

A light-projecting system for illuminating a central portion of a screen and a pair of peripheral portions on either side of the central portion in order to perform focus detection for each of the central portion and the pair of peripheral portions, comprises a first pattern for forming first illumination light for illuminating the central portion of the screen, and a second pattern common to the pair of peripheral portions, for forming second illumination light and third illumination light, different in light intensity distribution from the first illumination light, for illuminating the pair of peripheral portions separately, thereby providing the light-projecting system for automatic focus detection, permitting high-accuracy focus detection by expanding the illumination range.

Light-projecting system for automatic focus detection

A focus detection function is disposed on the focal plane of an objective lens. The in-focus state of the objective lens is determined with respect to a plurality of range-finding regions in a photographic range by employing the focus detection function. A correction value of the objective lens corresponding to a predetermined range-finding region among the plurality of range-finding regions is already stored, thereby finding correction values corresponding to regions other than the predetermined region. As a result, focus detection with respect to the regions other than the predetermined region can be performed.

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Tochigi, Japan

Yusuke Ohmura