Abstract: A real-image zoom finder optical system in which the objective lens system, the condenser lens system, the erecting optical system and the eyepiece lens system are arranged in this order from the object. The objective lens system includes a negative lens group (O1) and a positive lens group (O2), in this order from the object, and these lens groups are moveable along the optical axis upon zooming. Further, the negative lens group (O1) includes a negative meniscus single lens element (O11) having a convex surface facing towards the object, and a meniscus single lens element (O12) having a convex surface facing towards the image, in this order from the object.

Abstract: The invention relates to an optical imaging system for imaging an object with progressively adjustable magnification. The inventive system comprises an imaging plane for projecting an image field originating from the object and an imaging optical system situated on the object side in front of the imaging plane, preferably with a fixed focal length for producing the image field on the imaging plane. Said imaging optical system and/or said imaging plane are arranged so that they can move in the direction of the optical axis in order to adjust the magnification and/or focus the image appearing on the imaging plane.

Abstract: A real image mode variable magnification finder has an objective optical system with positive refracting power, an image erecting optical system, and an ocular optical system with positive refracting power. The objective optical system has a first lens unit with negative refracting power, a second lens unit with negative refracting power, a third lens unit with positive refracting power, and a fourth lens unit with negative refracting power. When the magnification of the finder is changed, at least one lens unit, namely the third lens unit is moved. In this way, the total length of the objective optical system can be reduced, and thus a compact finder is obtained.

Abstract: To provide a front tele-converter that may cause less aberrations and has a superior imaging quality though it has a high magnification, disclosed is a front tele-converter TC having an afocal magnification higher than 1.9, which is detachably mountable to a photo-taking lens L on its object side. The front tele-converter has, in order from the object side, a positive lens group GF having a positive refractive power and a negative lens group GR having a negative refractive power. The positive lens group GF has a positive cemented lens, the negative lens group GR has a positive lens with its convex surface facing the image side, and the lens groups fulfill a specific condition.

Abstract: The invention is directed to an infrared Kepler telescope which includes an objective defining an optical axis and including a positive front group and a negative rear group all arranged on the optical axis. The objective further includes an interchangeable optic interposed between the positive front group and the negative rear group with the interchangeable optic being configured to operate as a magnification changer. An ocular is mounted on the optical axis rearward of the negative rear group and the rear group and the ocular are fixedly pregiven. The positive front group is a first positive front group and is exchangeable with at least a second positive front group. The interchangeable optic is a first interchangeable optic and is exchangeable with at least a second interchangeable optic.

Abstract: A variable magnification optical system comprising four optical units each having a reflecting surface inclined with respect to a reference axis ray which is a ray passing from an aperture center of an aperture stop to a center of a final image plane, the variable magnification optical system being arranged to perform a magnification varying operation by moving at least two of the four optical units along the reference axis ray in such a manner as to vary an optical path length which extends along the reference axis ray from a predetermined position on an object side to the final image plane.

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: An optical system for a binocular is provided with an objective optical system, an erecting system and an eyepiece. The objective optical system includes a first lens having positive refractive power, a second lens having negative refractive power and a third lens having positive refractive power. The third lens is movable in a direction orthogonal to an optical axis to stabilize an image. The objective optical system satisfies the following relationships:0.05<d.sub.12 /f.sub.0 <0.20; and0.5<.vertline.tan 1.degree./(.phi..sub.13 -.phi..sub.12)<5.0 (unit: mm)where d.sub.12 is a distance between the first lens and the second lens, f.sub.0 is the focal length of the objective optical system, .phi..sub.12 is a composite power of the first and second lenses, and .phi..sub.13 is a composite power of the first, second and third lenses.

Abstract: A two-stage optical imaging system which is capable of operating in the infra red and which is compact, the system comprising an objective generally in the form of a Cassegrain system with primary and secondary mirrors A, B together with a relay C which may be reflective, refractive or refractive and diffractive, the relay C being located co-axially between the primary and secondary mirrors A, B.

Abstract: A method (400) of determining a custom illumination scheme for a projection-type photolithography system (500) is disclosed. The custom illumination scheme provides compensation for imaging system aberrations within the photolithography system (500) and thereby reduces critical dimension non-uniformities of features produced by the photolithography system (500) across a substrate (120). The method (400) includes the steps of performing a lithography simulation (404) for one or more nominal features using imaging system aberration data which characterizes the photolithography system (500) and an initial illumination scheme. The lithography simulation includes one or more simulated features which differ from the one or more nominal features due to the imaging system aberration data.

Abstract: A real-image finder optical system includes a positive objective optical system, an image-erecting optical system and an eyepiece optical system, in this order from the object. The image-erecting optical system includes a pattern display surface having a reflective pattern, and a half mirror surface, transmitting a portion of the light rays incident from the object, and again reflecting the light rays having been reflected from the pattern display surface. The real-image finder optical system forms a real image of the object formed through the objective optical system and a virtual image of a pattern on the pattern display surface formed by an optical system including the half mirror surface so that an operator can simultaneously view both the real image of the object and the virtual image of the pattern through the eyepiece optical system; and the real-image finder optical system satisfies the condition:0<d.sub.1 /f.sub.e .ltoreq.0.1 (1)wherein d.sub.

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 finder optical system has an objective optical system for forming an intermediate image of an object and an eyepiece optical system, and is disposed independent of a photographing optical system. The objective optical system includes a reflecting member. A lens unit situated on the object side of the intermediate image is used as a correcting lens and moved along the optical axis. The finder optical system is thus corrected for diopter and satisfies a condition:0.1<.vertline.1000.times..alpha..sub.F /f.sub.R.sup.2 .vertline.<7.0where .alpha.F is the maximum longitudinal magnification of the correcting lens and f.sub.R is the focal length of the eye-piece optical system.

Abstract: A real image mode zoom finder includes, in order from the object side, an objective optical system with positive refracting power having a first lens unit with negative refracting power, a second lens unit with positive refracting power, a third lens unit with positive refracting power, and a fourth lens unit with negative refracting power; an image erecting system for erecting an intermediate image formed by the objective optical system; and an ocular optical system with positive refracting power. In this case, each of lens units constituting the objective optical system is constructed with a single lens, and the object-side surface of the first lens unit is configured to be concave. Moreover, the objective optical system satisfies the following condition:2.5<.alpha..sub.T(R2) <5.7where .alpha..sub.T(R2) is a combined longitudinal magnification ranging from the second lens unit of the objective optical system to the intermediate image at the telephoto position of the finder.

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: The invention comprises a real image zoom finder including an objective lens group, an erecting group, and an eyepiece lens group. The objective lens group includes a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a positive refractive power, and a fourth lens having a positive refractive power. The surface of the fourth lens closest to the image side of finder is convex and the second lens is biconvex. The real image zoom finder has a simple structure and good performance for all magnification ranges.

Abstract: A real-image variable magnification finder includes an objective optical system of positive power, a condenser lens located at an image forming surface of the objective optical system, an eyepiece optical system of positive power, and an image erection optical system. The objective optical system of positive power includes a first positive lens group, a second negative lens group, a third positive lens group, and a fourth negative lens group. Upon change of magnification from the low magnification extremity to the high magnification extremity, the second lens group is moved to monotonically increase the distance between the second lens group and the first lens group; and the third lens group is moved to monotonically increase the distance between the third lens group and the fourth lens group while the first and fourth lens groups are kept immovable. The finder satisfies the condition defined by (1) 1.2<m.sub.4 <2, wherein m.sub.4 represents the lateral magnification of the fourth lens group.

Abstract: A system and a method of designing and mechanical packaging of a fully integrated multifunctional multispectral miniaturized sight assembly to allow its use on hand-held man-portable units. All the subsystems of the compact sight assembly, namely, a direct view day subsystem, a CCD-based visible TV subsystem, a staring IR night subsystem, an eyesafe laser rangefinding subsystem and a display subsystem for viewing the output of the TV or IR subsystem, are aligned and use a single telescope and eyepiece in order to decrease the size of the assembly. In addition, each sight assembly subsystem operates in a first and a second field of view, preferably in a narrow field of view and a wide field of view, with wavelengths from 0.45 .mu.m to 12 .mu.m, thereby creating a very small but highly powerful sight assembly.

Abstract: An ultra-broadband ultraviolet (UV) catadioptric imaging microscope system with wide-range zoom capability. The microscope system, which comprises a catadioptric lens group and a zooming tube lens group, has high optical resolution in the deep UV wavelengths, continuously adjustable magnification, and a high numerical aperture. The system integrates microscope modules such as objectives, tube lenses and zoom optics to reduce the number of components, and to simplify the system manufacturing process. The preferred embodiment offers excellent image quality across a very broad deep ultraviolet spectral range, combined with an all-refractive zooming tube lens. The zooming tube lens is modified to compensate for higher-order chromatic aberrations that would normally limit performance.

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: A viewfinder optical system has a relay optical system and an eyepiece optical system. The relay optical system has a first, a second, and a third relay lens. The eyepiece optical system has a first and a second eyepiece lens. The first eyepiece lens, which is disposed closest to a secondary-image plane formed by the relay optical system has an aspherical surface on its secondary-image plane side.

Abstract: A dual field optical system [20] comprises an objective [A, B,] which forms an intermediate image [10] and a relay [E, F,] which transfers radiation to a focal plane [12]. The objective [A, B] comprises a primary mirror [A] and a secondary mirror [B] arranged in the form of a Cassegrain system and is rendered dual-field by the provision of an alternative primary mirror [A.sup.1 ] which is axially movable between in-use and out-of-use positions. The primary mirror [A] forms part of a housing [J] for a linear actuator [15] which is connected by co-axial rods [14] to the alternative primary mirror [A.sup.1 ] so that the system is both compact and of low mass due to symmetry.

Abstract: A real image mode variable magnification finder includes an objective system having a positive refracting power, an image erecting optical system for erecting an image formed by the objective system, and an eyepiece system having a positive refracting power. The objective system is composed of a first lens unit of a negative biconcave lens, a second lens unit of a positive lens, and a third lens unit of a positive meniscus lens with a convex surface directed toward the image side. The first lens unit is fixed and the second and third lens units are moved along the optical axis, thereby changing the magnification of the finder. In this way, the real image mode variable magnification finder of wide-angle design can be provided which is compact in size, has a high variable magnification ratio, and exhibits excellent performance for correction for aberration.

Abstract: A relay lens system which may be used with, e.g., a video camera or still video camera so that these video cameras can use, as the image forming lens, various preexisting interchangeable image forming lenses originally designed for single lens reflex cameras. The image forming lenses which form a first image can have various exit pupils. The entry pupil of the relay lens system can be changed in accordance with each particular exit pupil by selecting one from a plurality of apertures or by a movable aperture. Consequently, a second image can be formed that reproduces the first image while maintaining good quality.

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: An optical system having a selected one of a pair of fields of view. The optical system includes a primary reflector; a secondary reflector; a refractive optical system; and a drive. The drive orients the secondary reflector to a first region in optical alignment with the primary reflector to provide the optical system with one of the pair of fields of view and for reorienting the secondary reflector to a second region out of optical alignment with the primary reflector and orienting the refractive optical system at the first region to provide a refractive optical system with a second one of the pair of fields of view. The optical system includes a detector and a second refractive optical system disposed between the first region and the detector. The detector comprises an array of detector elements.

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: A Keplerian variable magnification finder includes an objective system having a positive refracting power, an image erecting system for erecting an intermediate image formed by the objective system, and an eyepiece system having a positive refracting power. The objective system is composed of a first lens unit having a negative refracting power, a second lens unit having a positive refracting power, a third lens unit having a positive refracting power, and a fourth lens unit having a negative refracting power. At least two of these four lens units are moved along the optical axis so that the magnification of the finder is changed.

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: An optical system is provided with a plurality of field of view optical groups for insertion into the optical path. The field of view optical groups each subtend a prescribed field of view angle and are rotatably mounted on a rotary assembly for insertion into an operational position in the optical path. The rotary assembly is provided with hard stop contacts which rotate along a path and interact with stationary stops to locate the optical groups in the operational position. Additionally, movable stops are reciprocated into the rotation path of the hard stop contacts to provide additional modes, including a calibration mode. The system is also provided with extender optical groups which can be inserted in the optical path to provide intermediate fields of view between those of the field of view optical groups, thereby doubling the total number of fields of view available.

Abstract: A viewfinder having a high magnification ratio permits satisfactory correction of aberration in spite of its compact and simple structure. An objective lens group of the viewfinder includes a first lens unit having negative refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power and varies magnification by moving at least the second lens unit. Moreover, the first lens unit includes at least one negative lens, the second lens unit includes at least two positive lenses, and the third lens unit includes at least one negative lens. Furthermore, the positive lens is formed so that an object-side surface is aspherical and a predetermined condition is satisfied.

Abstract: A finder optical system is provided which is made up of an object lens system and an eyepiece system wherein the object lens system comprises, arranged from the object side:a first lens group, which has a negative lens L.sub.1,a second lens group, which has a positive lens L.sub.2, anda third lens group, which has a negative lens L.sub.3, and has an overall positive refractive power, and whereinthe eyepiece system is used for observing an image formed via the object lens system,the positive lens L.sub.2 of the second lens group in the object lens system has a bi-aspherical surface, andthe magnification of the finder optical system is changed by moving at least the second lens group in the object lens system along the optical axis.

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: 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: 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 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 reflecting illumination optical system for microscopes has a light source, a lamp house section including a collector lens with a focal length corresponding to the light source, and a reflecting projection tube section including a projection optical system for projecting the image of the light source at a position adjacent to the pupil of an objective lens. Further, a variable magnification section composed of a nearly afocal variable magnification lens unit is removably inserted between the reflecting projection tube section and the lamp house section, or in the interior of the reflecting projection tube section. Thus, when the lamp house section is replaced by another, the magnification of projection of the light source at the position adjacent to the pupil of the objective lens can be changed.

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: A magnification change-over device is arranged to be highly suitable for a camera of the kind having a photo-taking lens and a viewfinder arranged independently of each other. The device includes the photo-taking lens having an image magnification which is variable; the viewfinder which is arranged to have an image magnification thereof also variable; an operating device for varying the image magnification of the viewfinder; a detecting device for detecting the magnifying state of the viewfinder; and a driving apparatus for driving the photo-taking lens according to a detection signal of the detecting device when a shutter release operation is performed. After a magnification setting operation is performed on the viewfinder, the change-over device changes the magnification of the photo-taking lens according to the magnification of the viewfinder when a photographing operation is actually performed.

Abstract: A lens mounting arrangement (10) for, for example, an optical telescope, permits movement of the lens from an initial position to an accurately defined first position. The arrangement comprises a track (16) including a first stop (18) at a first end of the track, a lens carriage (12) moveable along the track, and a rotating drive (20) coupled to the lens carriage for moving the lens along the track and into contact with the stop, the stop defining the first position. A coupling (22, 26) is provided between the drive and the lens carriage and includes a resilient link (26) such that the lens carriage may be brought into positive contact with the stop, deformation of the resilient link accommodating excess movement of the drive.

Abstract: An eyepiece for use in a viewfinder optical system has a wide dioptric power adjustment range. The eyepiece is provided with, from a side of a secondary-image plane formed by a first, a second, and a third relay lens, a first, a second, and a third eyepiece lens having a positive, a negative, and a positive refractive power, respectively. For dioptric power adjustment, the positive first eyepiece lens or the negative second eyepiece lens is moved in an optical axis direction.

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: A super wide-angle variable magnification viewfinder includes an objective lens group of a positive refractive power. The objective lens group further includes 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, and a fixed fourth lens unit of a positive refractive power. Also included in the finder is a prism for erecting an image and an eyepiece lens group of a positive refractive power. The objective lens group forms an actual image of an object, and the actual image can be observed through the eyepiece lens group. The view finder satisfies the condition:1.75<L.sub.t /f.sub.T <1.87where f.sub.T is the focal length of the objective lens group at the telephoto position, and L.sub.t is the distance from a first lens surface of the objective lens group to a focus.

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.