Canon Kabushiki Kaisha

Kikuo Momiyama

Ryoichi Suzuki

Shinji Sakai

Masaharu Kawamura

Takashi Uchiyama

Tsunefumi Tanaka

Keiji Ikemori

Nozomu Kitagishi

Hiroyasu Murakami

Sadatoshi Takahashi

Kazuo Fujibayashi

Keiji Ohtaka

Hiromi Someya

Takashi Matsushita

Kenichi Kumazawa

Yasuyuki Yamada

Takashi Suzuki

Hideo Yokota

Susumu Matsumura

Kazuya Matsumoto

Shigeru Kamata

Shin Yamaguchi

Yujiro Agari

A zoom lens comprising, from front to rear, a first zoom section and a second zoom section, the first zoom section having a plurality of movable lens units which simultaneously move to effect zooming, and the second zoom section having a plurality of axially movable lens units, the light beam exiting from the rearmost unit in the first section enters directly the frontmost unit in the second section, and the refractive powers of the front and rear lens units are made positive and negative respectively, whereby the front and rear lens units are simultaneously moved in such a way that the magnifying power of the rear lens unit remains positive when the focal length of the entire system varies.

Zoom lens capable of obtaining focal lengths beyond a variable focal

The disclosed device prevents degradation of distance measurement accuracy due to alignment error in the mounting of a detachable lens barrel on a camera body. The lens barrel houses a focusing objective lens and a first distance measurement position is set along the optical path of the objective lens within the lens barrel. A second distance measuring position is set within the camera body. A light projector is positioned at one of the distance measuring positions and projects a measuring beam, and a photo detector is positioned at the other of the distance measuring positions to receive a reflection beam from the object being measured to produce a signal to be used for focus adjustment.

Focus detecting device

A focus detecting device arranged to detect the focusing condition of an objective lens by projecting a light flux from a light source onto an object through the objective lens and by sensing the light flux after it is reflected from the object. The focus detecting device is provided with sensors which produce information necessary for detecting the focal point of the objective lens by sensing the light of the light source reflected by the object. Degradation of the device's detection accuracy due to the eccentrically mounted objective lens is prevented when these sensors are symmetrically arranged relative to a plane containing the optical axis of the objective lens.

A zoom lens including, from front to rear, a first lens unit of negative power and a second lens unit of positive power with the separation therebetween being varied to effect zooming. The first lens unit is moved to effect focusing, wherein with the first lens unit focusing a finite object distance on the wide angle side, the second lens unit moves rearward to obtain focal lengths beyond the zooming range.

Zoom lens able to obtain focal lengths beyond the zooming range

The disclosed zoom lens includes, from front to rear, a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit. When zooming, the first and third lens units are axially moved independently of each other, the second lens unit remains stationary, and the fourth lens unit is axially moved but changes the direction of advance at an intermediate point in the zooming range.

High range zoom lens

A compact zoom lens including, from front to rear, a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power and, if desired, further a fourth lens unit, with the separations between the first and second units, between the second and third units and between the third and fourth units being made variable to vary the focal length of the entire system, wherein as the focal length is varied from the shortest to the longest value, the first and third units move axially forward, and the third unit is provided with a positive lens having an aspherical surface.

Compact zoom lens

An eye-piece constituting part of a finder optical system in a camera is constructed from three lens components, one of which is made axially movable to effect adjusting diopter, wherein the refractive powers and forms of all the components are so properly chosen as to maintain good stability of aberration correction throughout the adjusting diopter range.

Finder optical system for a camera

The disclosed zoom lens is composed of four lens groups. Counting from the front, the first lens group has a positive power, the second a negative power, the third a positive power and the fourth a positive or a negative power. At least the first, third and fourth lens groups are movable for zooming. The zoom lens satisfies the following conditions:

A zoom lens includes, from front to rear, a positive first component, a negative second component, a positive third component and a positive or negative fourth component. The first, third and fourth components are movable to vary the focal length of the entire system. In the wide angle position, the image modification of the third component contributes to the ratio of the focal length of the third component to the focal length of the fourth component, and the ratio of that fraction of the zoom ration of the entire system which the second component assumes to the zoom ratio of the entire system, satisfies specific conditions such that minimization of the bulk and size of the zoom lens and a stabilized correction of aberrations are achieved.

Zoom lens

A light measuring device for a camera has a light receiving photo-sensitive element, the light receiving surface of which is divided at least into two regions including a center part and a peripheral part and a diffusing member which is disposed in front of the photo-sensitive element and is arranged to have a diffusing surface formed solely in the peripheral area thereof. The light measuring operation of the device is arranged to be shiftable between one mode in which light measurement is carried out solely through the center part of the light receiving surface of the photo-sensitive element and another mode in which light measurement is carried out approximately through the whole light receiving surface.

Light measuring device for camera

In the single lens reflex camera including a photographic system having an objective lens and an image detector, and a viewfinder optically disposed of the photographic system and comprising a focusing screen having a transparent area surrounded by a light diffusing area, a prism for changing the direction of an optical path, and an eye-piece in sequence from the object, a light receiving element for light measuring is positioned away from an optical axis of the viewfinder in rear of an image forming lens for converging the light from the focusing screen to the light receiving element, and is provided with a mask for blocking the main part of an image of the transparent area which is formed by the image forming lens, thereby the proportionality between the variation of F-number of the objective lens and the amount of light measured is improved.

Single lens reflex camera with light measuring device

In the disclosed viewfinder, a focusing plate receives light from an objective via a reflex mirror, and after focusing, passes light to an eyepiece via a penta prism. A by-pass optical system receives light from outside the view field of the viewfinder and directs the light through an information carrier outside the optical path of the photographic light and into the penta prism so that the information can be displayed close to the view field of the viewfinder.

Finder for single lens reflex camera

In the disclosed apparatus, a photographic optical system passes light to an image plane on which a film or other sensor is to be arranged, and an optical member between the optical system and the image plane allows light from the optical system to pass while it directs light from the image plane toward a light sensor. The light sensor is outside of the light path from the optical system to the image plane.

Light measurement device for single lens reflex camera

A focus detection device for detecting the in-focus condition of an objective lens by arranging in rear of an image of an object to be photographed by said objective lens, second-image forming lenses for reforming said object image on the surfaces of photo-sensitive elements, wherein the output signals from said photo-sensitive elements are used to indicate the detection of the in-focus condition, whereby said second-image forming lenses are constructed in proper form to increase the accuracy of detection of the in-focus condition.

Focus detection device

A camera includes a viewfinder with an indicator having two opposing substrates sandwiching a liquid crystal between them. One substrate includes a common electrode arrangement with a plurality of electrodes. The other substrate includes a segmented electrode arrangement with a number of electrodes facing the respective electrodes of the common electrode arrrangement. Short-circuit connectors connect predetermined electrodes in the segmented electrode arrangement. A first contactor has a number of conductors connected to the respective electrodes of the segmented electrode arrangement to deliver predetermined drive signals thereto. At least one of the short-circuiting connectors is arranged at the input portion of the first contactor. A second contactor with a number of conductors is connected to respective electrodes of the common electrode arrangement so as to deliver predetermined drive signals thereto.

Growing community of inventors

Yokohama, Japan

Kikuo Momiyama