Abstract: The invention aims to provide binoculars suitable to be used in a theater or a sports stadium, which can provide a wide and bright field of view on one hand, and which are compact and lightweight with improved portability and maneuverability on the other hand. Inverse reflection of an image is achieved by providing optical systems of inverse reflection, each comprising a pair of specular reflectors opposed to each other on an object side and an eyepiece side, respectively, so that an optical axis of light exiting the optical system of inverse reflection on the eyepiece side extends in parallel with an optical axis of light entering the optical system of inverse reflection on the object side, and one or more object lens(es) is or are placed on one or more path(s) selected from optical paths of reflection from respective specular reflectors forming the optical systems of inverse reflection.

Abstract: A real image mode variable magnification finder includes, in order from an object side, an objective optical system with positive power, having at least three lens units; an image erecting device; and an ocular optical system with positive power. This finder also satisfies the following condition:0.1.gtoreq..beta..sub.W Z/D.sub.W .gtoreq.0.080where .beta..sub.W is a magnification at a wide-angle position of the finder, Z is the variable magnification ratio of the finder, and D.sub.W is an axial distance, in millimeters, from the object-side surface of the first lens unit of the objective optical system to the pupil-side surface of the third lens unit thereof at the wide-angle position of the finder. In this way, the real image mode variable magnification finder which Is small in size, high in magnification, large in angle of emergence, and easy to observe can be provided.

Abstract: A real image mode variable magnification finder optical system is provided with an objective system having a positive refracting power, a correctly erect image forming system having a plurality of reflecting members for converting an intermediate image formed by the objective system into a correctly erect image, and an eyepiece system having a positive refracting power. The objective system includes a first lens unit having a negative refracting power, a second lens unit having a positive refracting power, and a third lens unit having a negative refracting power. At least one of the light reflecting members is arranged between the third lens unit and a position of said intermediate image, and the first, second and third lens units are adapted to be moved along the optical axis when magnification of the optical system is to be changed. Thus, the finder optical system enables one to change magnification thereof with high ratios and to form a good image of visual field with decreased flare.

Abstract: A real image mode variable magnification finder has an objective system with positive refracting power, an image erecting optical system for erecting an object image formed by the objective system, and an eyepiece system with positive refracting power. The objective system includes a first lens unit with negative refracting power, a second lens unit with positive refracting power, and a third lens unit with positive refracting power, so that a space between the first lens unit and the second lens unit and a space between the second lens unit and the third lens unit are changed when the magnification of the finder is changed in the range from a wide-angle position to a telephoto position. The image erecting optical system has a first prism and a second prism so that a field frame is interposed between the first prism and the second prism. The finder also satisfies the following condition:-0.5<n/m<0.

Abstract: A sight including an infrared camera. A first admission aperture receives an incident image. The position of the first admission aperture is rotatable vertically and sideways. A mirror arrangement is rotatable about a common axis for derotation of the incident image. An output aperture is fixed with respect to the infrared camera. The incident image passes through the output aperture to the infrared camera.

Abstract: A branch image pickup and view system includes an objective lens system, an eyepiece lens system through which an image formed by the objective lens system is viewed, an image pickup surface which is adapted to pick up an image formed by the objective lens system, an optical separation system provided behind the objective lens system to split a bundle of light into a light bundle for the image pickup surface and a light bundle for the eyepiece lens system, an optical reduction system which is provided between the optical separation system and the image pickup surface, a condenser lens which is provided in the optical separation system to relay an image formed by the objective lens system to the eyepiece lens system, and an optical enlargement system which is provided between the optical separation system and the condenser lens.

Abstract: A real-image finder optical system is provided with an information display element located between an image plane of an objective optical system and a moving lens group of the objective optical system, and a partial mirror surface provided on an object side with respect to the information display element. The finder optical system includes the objective optical system having a positive power, an erecting optical system for erecting a reversed real image formed by the objective optical system, and an eyepiece optical system for observing the real image. Magnification of the finder optical system varies with the movement of at least one moving lens group of the objective lens system in a direction of an optical axis.

Abstract: In a variable magnification viewfinder of real image type in which an object image formed by an objective lens system of positive refractive power is converted into an erecting image by an image inverting optical system and the erecting image is observed through an eyepiece lens system, the objective lens system includes, in order from the object side, a negative first lens unit, a negative second lens unit and a positive third lens unit, and, during variation of magnification from the lowest magnification side to the highest magnification side, both the second lens unit and the third lens unit move toward the object side monotonically, so that a good optical performance throughout the entire range of variation of magnification can be attained.

Abstract: A real image finder optical system, having a relay lens system, comprises a positive first lens group, a positive second lens group, and a positive third lens group, in this order from the object. The finder optical system is arranged to form an inverted primary image of an object by the positive first lens group, and to form an erected secondary image by the positive second lens group functioning as the relay lens system so that the erected secondary image can be viewed through the third lens group. Furthermore, the second lens group comprises a diffractive optical element having at least one diffractive surface having positive diffractive power.

Abstract: A real image type zoom finder includes: an objective lens having a plurality of lenses, having a positive refracting power; a field diaphragm provided in the vicinity of a focal point of the objective lens, for defining a viewing field; a structure for erecting an image formed by the objective lens; and an eyepiece having a positive refracting power for enlarging an image formed by the objective lens and the field diaphragm. The objective lens includes at least a first lens group provided closest to an object side, having a negative refracting power, and satisfies the following conditions:1.9<f.sub.B /f.sub.W and1.0<.vertline.f.sub.1 .vertline./f.sub.W <2.0where f.sub.B represents a minimum value of a distance between a surface of the object lens closest to a pupil side and the field diaphragm, which is equivalent to a corresponding air gap, f.sub.1 represents a focal length of the first lens group, and f.sub.W represents a focal length at a wide angle end of the objective lens.

Abstract: A dual purpose optical device that is convertible between binocular and stereoscope modes of operation while using a common eyepiece arrangement for both. The device includes a housing containing a pair of optic supports mounted side-by-side for lateral movement towards and away from one another. Each support preferably carries three lenses. Two lenses on each support serve as the eyepiece and are aligned in a common plane with an eyepiece opening through the housing and a rotatable mirror assembly. The assembly pivots substantially ninety degrees from opposing forty-five degree angle positions with respect to the plane through the eyepiece opening and the eye and field lenses so as to fold the lines of sight either up or down within the housing. A circular photo transparency reel is received horizontally in a slot provided on an upper side of the housing.

Abstract: A zoom lens comprises a plurality of optical elements each of which includes a transparent body having two refracting surfaces and a plurality of reflecting surfaces and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from front surface mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: A real image finder system is disclosed. The finder system includes a common objective optical system for forming a real image of an object. A first erecting optical system for erecting an object image formed by the objective optical system, a first eyepiece optical system for observing an image erected by the first erecting optical system, a branch plane which is constructed as one plane of a plurality of reflection surfaces included in the first erecting optical system, and guides a luminous flux from the objective optical system to proceed along a first optical path and/or along a second optical path different from the first optical path, a second erecting optical system which is arranged on the second optical path and erects an object image formed by the objective optical system, and a second eyepiece optical system for observing an image erected by the second erecting optical system.

Abstract: An optical system includes a first optical element formed of a noncrystalline polyester resin having a copolymer ratio of 9,9-bis [4(2-hydroxyethoxy) phenyl]fluorene in a range of 35 molar percent to 45 molar percent when the dicarboxylic acid component is 100 molar percent, and a second optical element formed of material incorporating an ultraviolet light absorption agent and disposed at least either anteriorly or posteriorly to the first optical element.

Abstract: A viewfinding system for use with an optical system that creates a first object image includes an objective block which is sealed as a unit. The objective block includes a focusing screen for forming the first object image and relay optics for transmitting the first object image. A zoom block includes a zoom optical system for providing a modification of the magnification of the first object image to provide a second object image. An eyepiece block receives the second object image and includes a reflecting member and an eyepiece through which the second object image is observed. The eyepiece block is sealed and the second object image is realized within the sealed eyepiece block.

Abstract: Binoculars which are flat in the direction of view include two powerful Keplerian telescopes placed in two flat containers covering each eye and held by an eyeglass frame resting on the nose and ears; the binoculars can be easily converted into magnifying reading eyeglasses by touching a knob on the temple side of each telescope.

Abstract: A variable magnification optical system comprises at least three optical units which are a first moving optical unit, a fixed optical unit and a second moving optical unit. The three optical units are arranged in that order in a propagation direction of light, and a variation of magnification is effected by a relative movement between the first moving optical unit and the second moving optical unit.

Abstract: The optical reproduction system comprises an even number (e.g., four) of reflecting surfaces for producing an image rotated 90.degree. relative to an object to be produced, on an image plane that is parallel to the plane of the object. The incoming optical axis and the outgoing optical axis rest on the same straight line.

Abstract: Compact, low-cost keplerian variable-magnification viewfinders are disclosed that have a zoom ratio of at least 2 and simple composition that favorably corrects all aberrations. The viewfinders are useful for use with various types of cameras, and comprise a positive objective lens system and a positive ocular lens system. The objective lens system comprises, from the object side, first, second, and third lens groups preferably comprising a single negative lens, a single positive lens, and a single negative lens, respectively. Two of the first, second, and third lens groups are axially movable for adjusting the magnification of the viewfinder. The objective lens system preferably includes a fourth lens group preferably comprising a single positive lens. The ocular lens system preferably comprises at least a positive lens and a reflector array for producing an erect image. Several groups of embodiments satisfy respective conditional expressions.

Abstract: A binocular includes two parallel telescope systems. Each telescope system includes an objective system, an erecting system and an eyepiece system. The erecting system and the eyepiece system of each telescope system are part of a movable unit which is movable toward and away from a front-most lens of the objective system. The movable unit can be moved towards the front-most lens to a position in which an object cannot be viewed through the telescope system.

Abstract: A real image finder includes an objective lens group, an inverting group and an eyepiece lens group. The objective lens group includes a first lens unit of a negative refractive power, a second lens unit of a positive refractive power, a third lens unit of a positive refractive power, and a first prism of a positive refractive power, where an exit surface of the first prism is convex toward an image. The objective lens group forms an inverted image. The inverting group forms an erect image by inverting the image formed through the objective lens group. The eyepiece lens group magnifies the erect image formed by the inverting group.

Abstract: The present invention relates to a variable magnification finder comprising an objective lens group having a positive refractive power for enabling a wide angle view of an object. The objective lens group includes a first lens sub-group having either a negative or a positive refractive power; a second lens sub-group having a negative refractive power; a third lens sub-group having a positive refractive power and having a cemented lens with at least two pieces; and a fourth lens sub-group having a positive refractive power. The third lens sub-group is movable for magnifying the image, and the second lens sub-group is movable for compensating the focus of the magnified image. The finder further comprises an eyepiece lens group having a positive refractive power for viewing the image.

Abstract: A real image mode finder optical system has an objective system constructed with an objective lens including a single lens with positive refracting power and a first reflecting member; an intermediate image plane; and an ocular system constructed with a second reflecting member and an eyepiece including a single lens with positive refracting power. This finder optical system satisfies the following conditions:-4<r1/r2<-1, r2<0where r.sub.1 and r.sub.2 are radii of curvature of the surfaces of the objective lens which are located on the object and image sides, respectively.

Abstract: An optical system affords wide-angle imaging with a width in azimuth and a height in elevation respectively greater than and less than those of the field of view of an imaging device to which it is fitted. A median optical axis images a central format view on the optical axis of the imaging device, and two lateral optical paths image two lateral format views on a bearing axis at a bearing angle to the optical axis equal to the width in azimuth of the field of view of the imaging device. The three paths juxtaposed in the wide-angle field of view are superposed into a resultant format image.

Abstract: A zoom finder optical system of real image type of the present invention is provided with an objective lens system of a positive refractive power, a condenser lens of a positive refractive power and an eyepiece system of a positive refractive power from an object side. The objective lens system includes from the object side a first lens unit of negative refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power and a fourth lens unit of a positive refractive power.

Abstract: A real image finder includes an objective optical system which forms an image of an object to be viewed on a primary image forming surface, a viewing optical system which is adapted to view the object image formed on the primary image forming surface, and an image erection optical system having four reflection surfaces. The optical axis of the objective optical system is aligned parallel with the optical axis of an ocular optical system. Two of the four reflection surfaces of the image erection optical system are located before the primary image forming surface and the remaining two reflection surfaces are located after the primary image forming surface. The first two reflection surfaces are defined by mirrors and the latter two reflection surfaces are defined by a prism.

Abstract: A prism is provided having a surface on which light is made incident, surfaces at which light is reflected and a surface from which light is emitted. The prism includes an uneven surface portion provided on at least one of the incident, reflecting or emitting surfaces and located outside a light transmission area through which effective light of an associated optical system, in which the prism is to be incorporated, can be transmitted. The disclosure is also directed to a real image type view finder having such a prism.

Abstract: The present invention provides a real image type of zoom finder which, albeit having a zoom ratio as high as at least 3, is short in terms of the total length of an objective, is well corrected in terms of aberrations and ensures good viewing, and which comprises, in order from the object side, an objective having a positive refracting power, an optical system for inverting the upper, lower, left and right parts of an image formed by said objective, and an eyepiece having a positive refracting power, wherein the objective consists essentially of a first lens group G.sub.1 having a negative refracting power, a second lens group G.sub.2 having a positive refracting power, a third lens group G.sub.3 having a negative refracting power and a fourth lens group G.sub.4 having a positive refracting power, each consisting of one lens or the second lens group G.sub.2 consisting of two lenses, and conforms to the following conditional inequality (1):1.35<.vertline.f.sub.1 /f.sub.2 .vertline..times.m.sub.T <2.

Abstract: A real image mode finder optical system, situated separate from a photographing optical system, includes an objective system for forming an object image; an optical path splitting member for dividing a finder optical path formed by the objective system into a reflecting optical path and a transmitting optical path; a prism member whose refractive index is greater than 1, disposed on at least one of a surface on the reflection side and a surface on the transmission side of the optical path splitting member; a photometric member disposed on the reflecting optical path; and an eyepiece system situated on the transmitting optical path and disposed behind the optical path splitting member and the prism member. In this way, the real image mode finder optical system having a function for photometry keeps the number of parts to a minimum.

Abstract: A real image mode variable magnification finder optical system is provided with an objective system having a positive refracting power, a correctly erect image forming system having a plurality of reflecting members for converting an intermediate image formed by the objective system into a correctly erect image, and an eyepiece system having a positive refracting power. The objective system includes a first lens unit having a negative refracting power, a second lens unit having a positive refracting power, and a third lens unit having a negative refracting power. At least one of the light reflecting members is arranged between the third lens unit and a position of said intermediate image, and the first, second and third lens units are adapted to be moved along the optic axis when magnification of the optical system is to be changed. Thus, the finder optical system enables one to change magnification thereof with high ratios and to form a good image of visual field with decreased flare.

Abstract: An inner focus type telescope includes a sighting objective lens, a focusing lens, a horizon compensating optical system, a focal plane, and an eyepiece through which an object image formed on the focal plane can be viewed, arranged in this order from the object side. The position of the focusing lens is adjustable to form the object image on the focal plane in accordance with the distance of an object to be viewed. The telescope further includes a beam splitting optical system provided in the optical path between the objective lens and the focal plane to split the optical path, a surface equivalent to the focal plane, provided in the beam splitting optical system, and a focus detecting system which detects the state of the focus at the equivalent surface.

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, an 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 scope apparatus is provided with an image forming optical system and a condenser lens on the exit side of the image forming optical system. The condenser lens is positioned so that a convex exit surface thereof is disposed in the vicinity of the image plane of the image forming optical system.

Abstract: A variable magnification viewfinder comprises, from the object side, an objective lens group of an overall positive power, including a first lens unit of a negative refractive power, a second lens unit of a positive refractive power, a third lens unit of a positive refractive power and a fourth lens unit of a positive refractive power, wherein the objective lens group forms an actual image of an object, a reverse group for reversing an image formed through the objective lens group, and an eyepiece lens group for observing an image reversed through the reverse group, and where 2.4<L/fw<3.7, wherein, fw represents the focal length of the objective lens group at a wide angle position, L represents the distance between a closest surface of the objective lens group to the object and the actual image of the object formed by the objective lens group.

Abstract: A real-image variable magnification viewfinder includes, from the object side, an objective lens group of an overall positive power, including a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, and a fourth lens unit of a positive refractive power. The objective lens group forms an actual image of an object. The viewfinder also includes a reverse lens group for reversing an image formed by the objective lens group, and an eyepiece lens group for observing an image reversed by the reverse lens group.

Abstract: A Keplerian variable magnification finder includes, in order from the object side, an objective system having a positive refracting power as a whole; an image erecting system for erecting an intermediate image formed by the objective system; and an eyepiece system having a positive refracting power as a whole. The objective system including a first lens unit having a negative refracting power; a second lens unit having a positive refracting power; and a third lens unit having a positive refracting power. When the magnification of the finder is changed, the second and third lens units can be moved along the optical axis. The objective system satisfies the following conditions at the same time:0.1<.vertline.f.sub.1 /(f.sub.S Z).vertline.<0.40.2<f.sub.3 /(f.sub.S Z)<0.53where f.sub.1 is the focal length of the first lens unit, f.sub.3 is the focal length of the third lens unit, f.sub.S is the intermediate focal length of the objective system (f.sub.S =(f.sub.W f.sub.T).sup.

Abstract: An optical system for a real image type view finder having an objective lens system and an ocular lens system, including a first deflector and a second deflector. The first deflector has a first reflection surface which reflects on-axis light, incident thereupon along an optical axis of the objective lens system, towards an optical axis of the ocular lens system. The second deflector has an incident surface upon which light, reflected by the first deflector, is made incident, and second and third reflection surface to internally reflect that light incident upon the incident surface, before emitting the light through an exit surface toward the ocular lens system. The on-axis light incident upon the first deflector and the light reflected by the first deflector defines an acute angle therebetween. The second deflector satisfies the following relationships:90.degree.<.theta.<120.degree.90.degree.<.psi.<120.degree.wherein ".theta.

Abstract: Four cameras provide a 360 degree view of an area using a four sided pyramid shaped element. The four sides of the pyramid shaped element are reflective and reflect images from four different directions. Each camera is positioned to receive a reflected image from one of the reflective sides of the pyramids. The cameras are arranged so that they share a common virtual optical center.

Abstract: A 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 objective lens group consists of a first negative lens group and a second positive lens group, located in this order from the object side wherein first negative lens group and second positive lens group forming a movable variable focal length lens group. The first negative lens group comprises a double-aspheric lens which satisfies the following relationships:-0.5<.DELTA.X.sub.1-1 /f.sub.ow <0-0.10<.DELTA.X.sub.1-2 /f.sub.ow <0wherein .DELTA.X.sub.1-1 designates the aspheric value in the effective radius of a first surface of the double-aspheric lens; .DELTA.X.sub.

Abstract: A wide-angle variable magnification viewfinder comprises from an object side: an objective lens group of a positive refractive power, including a fixed first lens unit of a negative refractive power, a movable second lens unit of a negative refractive power for compensating the change of a view angle, a movable third lens unit of a positive refractive power for changing the magnification of the optical system, a prism for erecting an image, a fixed fourth lens unit of a positive refractive power; and an eyepiece lens group of a positive refractive power; wherein the objective lens group forms an actual image of an object and the actual image can be observed through the eyepiece lens group; and wherein -1.20<L.sub.t /f.sub.1 <-0.75, 0.04<m2w.times.m2.sub.t <0.13; where f.sub.1 represents a focal length of the first lens unit of the objective lens group, L.sub.

Abstract: An intermediate lens barrel for a microscope, in which an image is formed only once, the direction of the image does not change when returning to the original optical path, and no pupil aberration occurs. In this intermediate lens barrel, assuming that its round optical path is formed by n pieces of reflecting surfaces R (n being an even number not smaller than 4), an intermediate image is formed once in the round optical path, the angle formed by the normal N.sub.1 of the first reflecting surface R.sub.1 and the normal N.sub.2 of the second reflecting surface R.sub.2 with respect to each other when projected onto a plane orthogonal to the optical axis X.sub.1 reflected by the first reflecting surface R.sub.1 is .alpha..sub.1, the angle formed by the normal N.sub.N of the reflecting surface R.sub.N and the normal N.sub.1 of the reflecting surface R.sub.1 with respect to each other when projected onto a plane orthogonal to the optical axis X.sub.N reflected by the reflecting surface R.sub.N is .alpha..sub.

Abstract: A real-image zoom finder has an objective lens having a positive refractive power, and an eyepiece lens which is used for observing a real image of an object formed via the objective lens and has a positive refractive power. The objective lens includes, in the order from the object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, and attains zooming by moving at least the second lens unit along the optical axis. The objective lens satisfies the following conditions:-0.6<(R2+R1)/(R2-R1)<00.3<.vertline.f3.vertline./fT<0.

Abstract: Apparatus and methods are disclosed for re-imaging a primary image produced by a prime lens to form a positively demagnified secondary image at a secondary image plane, wherein the secondary image is smaller than, but has the same field angle as, the primary image. The apparatus comprises a field lens group and an optical relay. The optical relay can comprise a first lens group having negative refractive power, a second lens group having positive refracting power, and an erecting lens group interposed coaxially between the first and second lens groups. The apparatus also can comprise a beam-splitter imagewise to the optical relay to form multiple secondary images. The apparatus and methods have especial utility for adapting prime lens, designed for use on older, larger TV cameras, for use on newer, smaller TV cameras without sacrificing field angle.

Abstract: A real image mode variable magnification finder optical system has a finder objective for forming an optical path different from a photographic objective, an image erecting optical member for erecting an image formed by the finder objective, and an eyepiece having a positive refracting power. The finder objective includes the first lens unit having a negative refracting power, the second lens unit having a positive refracting power, the third lens unit having a negative refracting power, and the fourth lens unit having a negative refracting power, so that the second lens unit and said third lens unit are movable along the optical axis to change spaces among respective lens units from the first lens unit to the fourth lens unit. In this way, the finder optical system is obtained which bears a high variable magnification ratio, but is compact in size and provides good correction for aberration.

Abstract: A real-image finder having variable power includes an objective lens system of positive power, a condenser lens, and an ocular lens system. The objective lens system includes a first positive lens group, a second negative lens group, and a third positive lens group from an object side towards an image side. The second lens group is moved toward an image side and the third lens group is moved toward an object side, when the magnification changes from a wide angle side to a telephoto side. Thus, the distance between the first and second lens groups increases, the distance between the second and third lens groups decreases, and the distance between the third lens group and the condenser lens increases. The real-image finder meets the requirements defined by the relationships 0.5<.vertline.m.sub.2w .vertline.<1.0; 1.1<.vertline.m.sub.2T .vertline.; 0.5<.vertline.m.sub.3w .vertline.1,0; and, 1.1<.vertline.m.sub.3T .vertline., where "m.sub.2w " and "m.sub.

Abstract: A sliding binocular body has two optical assemblies which slide on an intermediate plate to adjust for intraocular distance and which slide closed. Two shells are joined to form one assembly. Front and back contour plates cover the assembly. A field and eye lens holder slides into the box through the back plate. An eye piece is attached to the lens holder. Inward horizontal surfaces have inward extending rails, which engage outward facing grooves on the intermediate plate. The two shells are secured together and joined to the intermediate plate before mirrors are slid and clamped into place. The objective lenses are placed in position, and the contour plates are sealed in place. The eye lens and field lens are inserted in the holders before the holders are inserted in the assemblies. The assemblies hold and clamp mirrors against fixed reference surfaces. Objective lens holders formed in the assemblies permit vertical or horizontal adjustment of an objective lens before its fixing.

Abstract: A real image type viewfinder optical system configured so as to allow observation, through an eyepiece, of an image of an object which is formed by an objective, and inverted by image inverting optical members in both a vertical direction and a horizontal direction. This viewfinder optical system uses an objective which is formed as a member integrated with a prism having a first reflecting surface of the image inverting optical members and an eyepiece which is formed as a member integrated with a prism having a final reflecting surface of the image inverting optical members.

Abstract: A mechanism for adjusting the diopter setting of a finder assembly which has an objective optical system and an eyepiece optical system, includes an object side image forming position adjusting device which adjusts the position where an image is to be formed by the objective optical system. The mechanism effectively compensates for any change that occurs in the position where an image is formed by the objective optical system due to temperature or humidity variations. Thus, the problem of plastic lenses having their focal lengths extended in a hot and humid environment is solved by the invention.

Abstract: An asymmetric binocular viewing device having a first and a second optical axis forming a horizontal plane. A single objective, a related luminance intensifier tube, a semi-reflecting optical image splitter and a first ocular are aligned in succession the first optical axis. A second ocular related to the optical image splitter by an optical image transmitting system is aligned on the second optical axis. The optical image transmitting system includes in succession a first mirror, an lens system, a second mirror, and a third mirror. The elements are arranged so that an optical path is defined starting from the optical splitter and including a first vertical axis section, a horizontal axis section, and a second vertical axis section describing a U turned upside down in the shape of a bridge located on a vertical plane and perpendicular to both parallel first and second optical axes. This defines a free space between both the first and second oculars freeing up the space for the user.

Abstract: A prismatic telescope optical system is available to include one of a plurality of optical systems different in magnification from one another, each having an objective system, an image erecting prism system, and an eyepiece system. Each of plurality of optical systems is constructed so that its respective overall length is are made practically equal by varying the refractive indices of an included image erecting prism system.