Abstract: A zoom viewfinder system for a single reflex camera comprises a relay optical system through which said first object image is formed as a second object image and plural reflecting members for reflecting light rays of said first object image, wherein the reflecting members except one reflecting member provided closest to a first object image is moved in order to adjust an angle of light rays of the first object image to the reflecting members. The zoom viewfinder system also comprises a holder for holding the reflecting members located parallel in the relay optical system in order to determine relative positions of the reflecting members precisely. The zoom viewfinder system further comprises holding members for holding plural parts of an optical system respectively, wherein each part is fixed to compose a viewfinder system, so that assembly and maintenance can be easy and the optical axis can be prevented from deviating.

Abstract: A finder optical system including an objective system, an image erecting system for erecting an object image formed by the objective system, and an eyepiece system for observing the object image. These systems are constructed of low-hygroscopic organic materials. Thus, the finder optical system can prevent transient variations of optical properties caused by hygroscopicity.

Abstract: A real image mode variable magnification finder optical system is provided with an objective lens having a positive refracting power and an eyepiece having a positive refracting power. The objective lens includes the first lens unit having a negative refracting power, the second lens unit having a positive refracting power which is movable for varying magnification, and the third lens unit having a positive refracting power which is movable for varying magnification. Moreover, the objective lens has the first reflecting surface for erecting an image on the entrance side of the region of a space provided on the object side of the second lens unit to move lenses when a change of magnification is made, and the second reflecting surface for erecting the image between the third lens unit and an intermediate imaging plane. Thus, the finder optical system brings about a reduction of thickness of a camera body, favorable correction for aberration, and cost reduction.

Abstract: A real image mode finder optical system includes an objective lens, a relay lens, and an eyepiece. A plurality of reflecting surfaces is arranged between the objective lens and the eyepiece. At least one of the reflecting surfaces is movable for deflecting an optical axis, and thereby an optical component disposed behind this reflecting surface is moved in accordance with the deflected optical axis. Thus, a variable angle is provided in a wide range from an eye level to a waist level.

Abstract: A finder optical system includes a finder objective lens provided independent of a photographic objective lens, an image erecting unit for erecting an image formed by the finder objective lens, and an eyepiece. The distance from a surface, closest to an image, of the finder objective lens to a surface, closest to an object, of the eyepiece is changed and at the same time, the focal length of the eyepiece is also changed, thereby converting the state of ordinary photography into the state of panoramic photography. Thus, in the panoramic photography, aberration is favorably maintained and finder magnification is improved.

Abstract: A spyhole viewer for a door or wall, includes an objective system for producing a real, inverted image. The objective system is mounted in a tubular member fixedly installable in the door or wall. An erector is provided for inverting the inverted image of the objective system and is located behind at least one of the elements of the objective system. At least one reflector is provided for angularly deflecting the light beams from the objective system, and a housing is fixedly attachable to the tubular member for accommodating at least the erector and the reflector. A viewing lens is provided for magnifying the real image as inverted by the erector means. The viewing lens is adapted to swivel in a substantially vertical plane about an imaginary horizontal axis at a radius of swivel at least approximately equal to the length of the light path from the image-side focal plane of the objective system to the first principal plane of the viewing lens.

Abstract: A real image type viewfinder is provided with, in the following order from the object side: an objective lens group, a condenser lens group which transmits the image of the object formed by the objective lens group towards an eyepiece lens group, an image erecting optical system that erects an inverted image, and, the eyepiece lens group. The eyepiece lens group consists of a negative lens and a positive double-convex lens, in this order from the eye side, and satisfies the following three relationships:-0.5<f.sub.E /f.sub.E1 <0 (1)-1.5<f.sub.E /r.sub.E1 <1.0 (2)0.03<d.sub.E1-2 /f.sub.E <0.1 (3)wherein f.sub.E designates the overall focal length of the eyepiece lens group; f.sub.E1 designates the focal length of the negative lens of the eyepiece lens group; r.sub.E1 designates the radius of the eye-side surface curvature of the negative lens of the eyepiece lens group; and d.sub.

Abstract: A real image mode finder optical system includes an objective system having a positive refracting power as a whole, an image erecting system for erecting an image, and an eyepiece system having a positive refracting power. The objective system has a meniscus lens with a negative refracting power, whose convex surface is directed toward the eye, and an objective lens with a positive refracting power. Thus, even when finder magnification is high, a wide field angle can be derived and the distance between the last surface of the eyepiece system and the eyepoint can be ensured in a long range, with a resultant easy observation.

Abstract: A spyhole viewer, mountable in a wall surface is disclosed and provides a wide angle view, while requiring a small diameter mounting hole. An objective lens system produces a real inverted image, a reflector angularly deflects light from the objective lens system, and an erector, located behind an element of objective lens system, erect the image. Further, a image surface upon which the image will appear, and a projection viewing lens are provided. The image optical axis is angularly deflected at least once between the objective and viewing lens systems.

Abstract: A real image mode variable magnification finder optical system has an objective lens system including a first lens unit of negative refracting power, a second lens unit of positive refracting power, and a third lens unit of negative refracting power, provided with positive refracting power as a whole; and image erecting system for erecting an image of an object; and an eyepiece system for observing the erected image, in which the first and second lens units are moved and the third lens unit is fixed to vary magnification. Thus, the finder optical system has important advantages in practical use that its overall length is reduced, aberrations are favorably corrected, and manufacturing costs are low.

Abstract: A monocular telescope in which the beam path is so laid out that the casing may be flat in the direction of view, and the optical axis of the beam path in the casing describes a somewhat rectangular route, and in which the telescope has a view finder beam path intesecting with the telescope beam path in the users eye.

Abstract: A real image mode variable magnification finder optical system comprising an objective lens system including a rotatable prism, an image erecting optical system for erecting an image formed by the objective lens system and an eyepiece lens system having a positive refractive power. The prism is rotated 180.degree. for changing the finder optical system between a wide angle condition and a telephoto condition. This variable magnification finder optical system permits minimizing a space required for operating an optical member for changing a magnification thereof and composing the objective lens system compactly of a small number of component parts.

Abstract: The invention is directed to an electro-optical rangefinding-type apparatus which uses electronic sensors to detect the position and orientation of the apparatus relative to a fixed point. Data from the sensors is relayed to a microprocessor which can calculate parameters such as range, horizontal distance and angle, vertical distance and angle, relative speed and magnetic bearing of a target objective, which are then displayed. A preferred embodiment of the invention is convertible between the functions of a stereoscopic binocular and a coincidence-type range-finder and means are provided for converting the apparatus to and from the binocular and rangefinding modes.

Abstract: An erect image finder is provided in which a real erect image formed by an objective optical system can be observed through an erect image forming optical system having a plurality of reflecting surfaces and an eyepiece optical system. The erect image finder includes a plate-like mirror which constitutes a first reflecting surface of the erect image forming optical system, and a prism separate from the mirror which defines the other reflecting surfaces.

Abstract: A real image mode variable magnification finder optical system includes an objective lens system having a positive refractive power as a whole, an image erecting system for erecting an intermediate image formed by the objective lens system, and an eyepiece system having a positive refracting power as a whole, in which the entrance surface of the image erecting system has a negative refracting power and an intermediate image is formed between the entrance surface of the image erecting system and the eyepiece system. Thus, the real image mode variable magnification finder optical system, although it is such an optical system that an erect image is obtained by a Porro prism system constructed of a plurality of reflecting members, has important advantages in practical use that a finder length is reduced, optical performance is favorable, design is compact, and finder magnification is high.

Abstract: The invention relates to an episcopic sight usable for observation and firing by day or night on a vehicle equipped with a gun. The sight includes an assembly of interchangeable moduli grouping the optical elements, particularly made of a head modulus 1 containing a mirror controlled in elevation, a height increase modulus 2, a day sight modulus 4, a night sight modulus 5, a rangefinder modulus 6, an electronic case associated to a fire-control computer. It includes a modulus of separation 3 of the day and night channels interposed between the height increase modulus 2, and the day and night moduli 4, 5, the modulus of separation 3 containing the means for generating a sight reticle in the day and night channels. The means of generating a firing reticle include a projection collimator of this reticle and a rhombohedron to inject this reticle into the day and night moduli.

Abstract: A door viewer includes two prisms of rectangular isosceles triangle shape in cross section whose hypotenuse surface abut horizontally, a front convex lens and a plano-convex eyepiece lens. The front convex lens has a front concave surface and a rear convex surface to correct chromatic aberration. The convex surfaces of the front and eyepiece lens are positioned face to face with each other to correct barrel distortion. The view casts an image onto a ground glass section formed on or provided abutting the eyepiece lens.