Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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:-3<.beta.3w<-0.8-0.35<f3/f4<0.430.5<Z2/Z<11<f1/fw<1.70.3<.vertline.f2.vertline./fw<0.48where fi is focal length of the i-th lens group, Z2 is the amount of variation of the magnification power of the second lens group with zooming, .beta.3W is the magnification power of the third lens group in the wide angle position, fw is the shortest focal length of the entire system, and Z is the zoom ratio of the entire system.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: The present invention relates to a liquid crystal cell having a plural number of electrode pairs arranged on both sides of the liquid crystal matter so as to be opposed to each other, being characterized in that a pulse wave generating device for generating the first pulse wave with smaller amplitude than the threshold valve for lighting the liquid crystal and the second pulse wave with larger amplitude than the threshold value for lighting the liquid crystal in reversed phase to each other and a gate device for selectively applying the outputs of the pulse wave generating device to each electrode of the liquid crystal cell in accordance with the input signal are provided. Thus only the voltage between the selecting electrodes is highter than the threshold value. An input change over device is provided so as to change over the input signal group in a time dividing way in such a manner that a plural number of dots can be displayed visually at the same time, as a result, the wiring is simplified.

Abstract: A liquid crystal display device for a camera includes a display member having liquid crystal material for providing a display of photographic information, and a focusing glass for forming an image of an object which is to be photographed. A mask is arranged to face the display member and the focusing glass, the mask including a first transparent part which faces a display part of the display member, and a second transparent part which faces the object image formed on the focusing glass. A light shading part is provided between the first and second transparent parts of the mask to shade an end part of the display member from light. The mask enables view finder optics provided in the camera to display a rectangular view field having straight sides to the camera user.

Abstract: The wide angle objective of the inverted telephoto type with a high relative aperture. It includes from front to rear, a first lens group of negative power, a second lens group of positive power and a third lens group of positive power, well corrected for the various aberrations with predetermined conditions for the focal length of each lens group, lens form and refractive indices of the glasses of the lens elements.

Abstract: A wide angle objective of the retrofocus type, with an increased aperture, is disclosed. This objective comprises three lens groups of which the first counting from the front has a negative power and includes, from front to rear, a positive lens in the meniscus form convex toward the front, a negative lens in the meniscus form convex toward the front, a negative lens likewise in the meniscus form convex toward the front, a positive lens, and a negative lens in the meniscus form convex toward the front. The second lens group includes a cemented bi-convex lens, and the third lens group includes a cemented lens of positive and negative lens elements, a positive lens in the meniscus form convex toward the rear, a cemented lens of negative and positive lens elements, and a positive lens. A diaphragm is positioned in the space between the second and third lens groups. Various conditions are prescribed for every lens group, and for every lens in each group.

Abstract: In the single lens reflex camera disclosed, an elongated entrance window extending across a plane through the roof ridge of a roof pentaprism, and a smaller entrance window more remote from the plane, form a pair of windows, one of which produces light emerging from data on the camera lens barrel, and the other from data at another camera location. A mirror turns light from one of the data transverse to the plane before it is introduced through one of the windows while light from the other of the data is introduced into the other window. The prism directs the lights to the lower portion of an ocular. In a preferred embodiment, the data turned by the mirror is from the lens barrel.