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: 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: 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 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 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: An improved zoom telescope which has a freely rotatable annular zoom ring connected through an interposition gear to a cam cylinder.

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 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 zoom lens system is composed of three lens groups. Arranged in the order from an eyepoint side are a first lens group G.sub.1 having a positive refracting power, a second lens group G.sub.2 having a positive refracting power and movable along an optical axis during the period of zooming, and a third lens group G.sub.3 having a negative refracting power and movable along the optical axis during the period of zooming. In the second lens group G.sub.2, at least one positive lens includes a lens surface composed of an aspheric surface at least on one of its eyepoint side and object side. Not only a sufficient eye relief is ensured but also various aberrations are corrected throughout the whole zooming range.

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: 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: 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: An optical assembly (10) includes a first plurality of optical elements (14) providing the viewer a first field of view and a second plurality of optical elements (18) that, when moved into the optical path (16), provides the viewer with a second field of view. A support structure (36) for the second plurality of optical elements (18) includes a permanent magnet (64) that is disposed to cause a switch (66) located on the housing (12) of the optical assembly (10) to close. The changing of the position of the switch (66) results in a signal being provided to identify to the viewer which field of view is being presented by the assembly (10).

Abstract: A Keplerian zoom finder optical system comprises an objective lens group having a positive refracting power on the whole and constructed of, in order from an object side, a first lens unit having a negative refracting power, a second lens unit having a positive refracting power, a third lens unit having a negative refracting power and a fourth lens unit having a positive refracting power. This finder also comprises a regulating element, disposed in the vicinity of a focal position of the objective lens group, for regulating a visual field. The finder further comprises an eyepiece unit having a positive refracting power. The finder varies a magnification by moving at least the second lens unit along an optical axis and satisfies the following condition:-5<f.sub.3 /f.sub.w <-3wheref.sub.w : the synthetic focal length of the first and second lens units in a minimum magnification state, andf.sub.3 : the focal length of the third lens unit.

Abstract: A thermal imaging device (10) provides for its use with a variety of accessory telescopic lenses (12). Each of the accessory telescopic lenses (12) and the thermal imaging device (10) include cooperating physical features allowing the lenses (12) to be mated with the device (10) in a single relative position. Each lens (12) also carries a uniquely positioned magnet (176), and the thermal imaging device (10) includes a plurality of magnetically-responsive sensors (178) responding to the magnets (176) of the various lenses (12) to identify which (if any) of the accessory lens (12) is installed on the device (10). Some of the accessory lenses (12) also include a variable-power feature. These variable-power lenses (12) have an additional magnet (182) moving between an effective position and an ineffective position in response to a user-selected power setting for the lens (12).

Abstract: The present invention provides an erector system characterized by centered erector lenses and lens holder movement capability to alter relative erector lens placement. Alignment of the erector lens optical centers facilitates the reduction of the phenomenon of trackout. Alteration of relative erector lens position permits a pistol scope or another device embodying the erector system to operate at more than one magnification.

Abstract: An objective has a first group of lenses with a first optical axis and a second group of lenses with a second optical axis. The optical axes are offset from and parallel to one another. A pair of Porroprisms is disposed between the first lens group and the second lens group and serves to rotate images. The Porroprisms cause a shift in optical axis, and the first and second optical axes are spaced from each other by a distance corresponding to this shift. The arrangement is such that light travelling along the optical axis of one lens group can enter the Porroprisms for reflection to the optical axis of the other lens group. The first lens group has negative refractive power while the second lens group has positive refractive power. A rhomboidal prism is located on the side of the second lens group remote from the Porroprisms and functions to cause a shift in optical axis equal but opposite to the shift caused by the Porroprisms.

Abstract: A Keplerian zoom finder optical system has an objective lens comprising, in succession from the object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of positive refractive power and having positive refractive power as a whole, and an eyepiece of positive refractive power for enlarging and observing the focused image of the objective lens therethrough. The air gap between the first lens unit and the second lens unit is varied to thereby vary finder magnification.

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: 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.

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: Telescopic optical systems of a binocular have respective objectives movable along respective optical axes for focusing on an object, and respective power-varying lens assemblies movable along respective optical axes for varying magnifications. One of the objectives is manually movable independent of the other objectives for diopter difference adjustment. The binocular has a manually operable mechanism for actuating the power-varying lens assemblies to adjust the magnifications independently of each other, to equalize the magnifications regardless of angular movement of the telescopic optical systems about the optical axes of the objectives for interpupillary adjustment. Electric motors for moving the objectives into an in-focus condition and moving the power-varying lens assemblies to vary the magnifications synchronously, are disposed on one side of a plane interconnecting the optical axes of the objectives. Batteries for energizing the electric motors are disposed on the other side of the plane.

Abstract: A zooming monocular or zooming binoculars having an objective optical system and an eyepiece optical system, which includes at least one variable power lens group driven in the optical axis in the eyepiece optical system, a movable field stop which is provided to define the field of view so as to move in the optical axis direction independently of the variable power lens group, and driving means for moving the movable field stop in association with the movement of the movable variable power lens group in the optical axis direction along a track different from a track of the movement of the movable power lens group. The power is varied by moving a part of the eyepiece or ocular optical system and a reference diopter is maintained constant upon variations of the power at -1.+-.0.5 diopter.

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 compact, simple real image finder includes an objective, a field lens, erecting optics and an eyepiece. The field lens is separated from an internal image sufficiently that it contributes substantially to the magnification of the finder.

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 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: An optical assembly (10) includes a first plurality of optical elements (14) providing the viewer a first field of view and a second plurality of optical elements (18) that, when moved into the optical path (16), provides the viewer with a second field of view. A support structure (36) for the second plurality of optical elements (18) includes a permanent magnet (64) that is disposed to cause a switch (66) located on the housing (12) of the optical assembly (10) to close. The changing of the position of the switch (66) results in a signal being provided to identify to the viewer which field of view is being presented by the assembly (10).

Abstract: A real image type of variable power view finder is disclosed which has an objective lens system, an image erecting optical system, and an eyepiece lens system, located in this order as viewed from an object to be photographed. The objective lens system includes negative and positive lens groups located in this order from the object side, so as to vary the distance therebetween, to change the magnification. The negative lens group of the objective lens system has at least two negative lenses.

Abstract: An apparatus (10) for removable attachment to the adjustment ring (26) of telescope sights (12) for firearms (14) or the like is disclosed including a pinch clamping band (28) having an integral, elongated linear projection (42) extending axially therefrom. The clamping band (28) includes a split, annular wall (30) having a transverse radial cut defining first and second, free ends (32, 34). The free ends (32, 34) of the annular wall (30) are drawn together by a bolt (40) extending between bosses (36, 38) extending outwardly from the annular wall (30) on opposite sides of the transverse cut. A lever (50) has a securement end (52) positionable between the free ends (32, 34) of the annular wall (30) and including an aperture (60) for slideably receiving the bolt (40). The lever (50) extends axially from the clamping band (28) parallel to the axis (A) of the adjustment ring (26) and the projection ( 42).

Abstract: A real image type variable power finder includes an objective lens system, an ocular lens system, a condenser lens, and an image erecting optical system. The objective lens system includes a first lens group having a negative power and a second lens group having a positive power in this order from the object side, so that the two lens groups being removed to vary the magnification. The second lens group has a negative lens and a positive lens in this order from the object side. The variable power finder satisfies the relationships:(1) 2.5<f.sub.E /f.sub.S <4.0;(2) -0.7<f.sub.S /f.sub.1 <-0.3 (f.sub.1 <0);(3) 0.4<f.sub.S /f.sub.2 <0.8;and(4) -0.3<f.sub.S /f.sub.2-1 <-0.05 (f.sub.2-1 <0);wherein "f.sub.E " designates the focal length of the ocular optical system, "f.sub.S " the effective focal length of a lens system including the objective lens system and the condenser lens on the short focal length side, "f.sub.

Abstract: Binoculars designed to provide a large aided static field of view are provided. The binoculars are characterized by S/D ratios of above 2.8, where S is the binocular' aided static field of view calculated by multiplying the binoculars' magnifying power by the binoculars' semi field of view in object space and D is given by tan.sup.-1 [(R.sub.ex +1.5)/13], where R.sub.ex is the radius of the binoculars exit pupil and where R.sub.ex and the constants 1.5 and 13 are measured in millimeters. As a result of the increased S/D ratio, the binoculars' of the invention minimize the sensation of tunnel vision which normally occurs when binoculars are used and reduce the user's apprehension of missing activities in his or her peripheral vision. In certain embodiments, a movable field lens unit is employed to provide variable power and a negative corrector lens unit is employed for aberration correction and to minimize the size of the binoculars. The binoculars are suitable for mass production and general consumer use.

Abstract: A finder optical system includes an objective system having a positive refracting power, a reflecting member having a field frame of variable shape, for erecting an image, and an eyepiece system having a positive refracting power. At least one positive lens unit of the eyepiece system is moved along the optical axis, and at least one positive tens unit is inserted in the optical path of the eyepiece system. The magnification of the finder optical system can thus be increased.

Abstract: A zoom finder of a real image type has an objective lens having positive refracting power and an eyepiece having positive refracting power. The objective lens is constructed by first, second, third and fourth lens groups sequentially arranged from an object side. The first lens group has positive refracting power. The second lens group has negative refracting power. The third lens group has positive refracting power. The fourth lens group has positive refracting power. The zoom finder is constructed such that a real image is focused and formed by the objective lens between the fourth lens group and the eyepiece and is observed through the eyepiece. A magnification of the zoom finder is increased by moving the second lens group from the object side to an eyepiece side. A change in diopter caused by this increase in magnification is corrected by moving the fourth lens group. In accordance with the above structure, an entire length of the zoom finder is short and is not changed in a zooming operation.

Abstract: A real image type of variable power view finder is disclosed which has an objective lens system, an image erecting optical system, and an eyepiece lens system, located in this order as viewed from an object to be photographed. The objective lens system includes negative and positive lens groups located in this order from the object side, so as to vary the distance therebetween, to change the magnification. The negative lens group of the objective lens system has at least two negative lenses.

Abstract: A variable power telescope with an automatic adjustment feature which enables the user of a firearm to automatically and quickly adjust the magnification power of the telescope while maintaining a secure grasp on the firearm with both hands and without losing the target viewed through the telescope. The magnification of the telescope is controlled through a battery-powered motor which can be operated by a switch near the trigger hand, allowing control with one finger on the user's trigger hand. The telescope also prevents operation of the motor beyond the adjustment range of the telescope by providing a shut-off switch that serves as a limit switch at the operational extremes of the telescope.

Abstract: A Keplerian zoom finder optical system has an objective lens comprising, in succession from the object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power and a third lens unit of positive refractive power and having positive refractive power as a whole, and an eyepiece of positive refractive power for enlarging and observing the focus image of the objective lens therethrough. The air gap between the first lens unit and the second lens unit is varied to thereby vary finder magnification. The Keplerian zoom finder optical system satisfies a predetermined condition.

Abstract: Binoculars designed to provide a large aided static field of view are provided. The binoculars are characterized by S/D ratios of above 2.8, where S is the binoculars' aided static field of view calculated by multiplying the binoculars' magnifying power by the binoculars' semi field of view in object space and D is given by tan.sup.-1 [(R.sub.ex +1.5)/13], where R.sub.ex is the radius of the binoculars' exit pupil and where R.sub.ex and the constants 1.5 and 13 are measured in millimeters. As a result of the increased S/D ratio, the binoculars of the invention minimize the sensation of tunnel vision which normally occurs when binoculars are used and reduce the user's apprehension of missing activities in his or her peripheral vision. In certain embodiments, a movable field lens unit is employed to provide variable power and a negative corrector lens unit is employed for aberration correction and to minimize the size of the binoculars. The binoculars are suitable for mass production and general consumer use.

Abstract: An afocal zooming optical system includes, in order from the object side, an objective optical unit comprising a positive first lens group, an erecting prism component and a negative second lens group, and an eyepiece optical unit comprising a three-element positive third lens group and a single-element positive fourth lens group, which system performs zooming by moving the second and third lens groups in different directions along the optical axis and satisfies certain conditions.

Abstract: An auxiliary lens attachment, installed a prescription or colored enhancement lens, is mounted onto an end of a rifle scope. The auxiliary lens attachment includes an adaptor having a lens receiving portion at a first end, a lens securing portion in a middle and a rifle scope mounting portion at a second end. A distance adjusting member is positioned on the securing portion of the adaptor to adjust the distance between the securing portion and the mounting portion.

Abstract: A variety of optical systems can be formed from select configurations of micro-optic multiplets (MOM) comprised of two or more microlens modules (MLM). The MLMs themselves are formed from planar arrays of microlenses. An optical system configured in accordance with the present invention forms a single primary image, together with a set of images transversely displaced from an optic axis and is characterized by the property that the image distance and the object distance move in the same direction, in stark contrast to known lens systems. For example, when an object distance decreases, the corresponding image distance also decreases with the present optical system.

Abstract: An all reflective multiple field of view optical system has a first (10) and second (12) objective assembly sharing a common eyepiece assembly (16) in a common packaging volume in a single unit. The second objective assembly is movable with respect to the first to provide multiple fields of view utilizing a common entrance pupil region (18) and viewing exit pupil plane (20).

Abstract: A power change mechanism for variable power riflescopes includes a resilient member disposed between the riflescope housing and the power change ring for automatically rotating the power change ring from one power setting to another upon activation of a latch mechanism. The automatic power change mechanism may include apparatus for overriding such automatic capabilities in order to provide for manual power change.

Abstract: A variable power hunting scope has an objective, an eyepiece, and a barrel therebetween. The barrel carries a reticle, a zoom assembly, a vertical cross-hair, a horizontal cross-hair, vertical and horizontal posts, and an adjusting ring for altering the scope magnification. A locking mechanism interferes with rotation of the adjusting ring at a desired maximum magnification setting, the desired maximum magnification setting being between the minimum and maximum magnifications of the scope.

Abstract: Adjustment means for a scope having a tubular body and a zoom ring mounted on the tubular body for varying the magnification power of the scope are disclosed. A first gear is concentrically mounted on the zoom ring for rotation therewith, and a second gear is carried on the tubular body and is engageable with the first gear. The second gear has a concentric shaft, and manual, electro-mechanical or dual means for rotating the shaft are provided. When the scope is used with a rifle, the means for rotation may be adjusted by a shooter without removing one hand from the firing position.

Abstract: The present optical system provides an all-reflective zoom optical system (10, 12, 14,16 and 60, 62, 64). An imaging mechanism including one or more movable mirrors (12, 14, 16 and 60, 62) is utilized to effect the change in the magnification, field of view or both of the system.

Abstract: A Keplerian zoom finder optical system includes an objective lens unit comprising a forward group having negative refractive power and a rearward groups having positive refractive power, the objective lens unit having positive refractive power as a whole and having the magnification changing function of changing the finder magnification by the spacing between the forward group and the rearward group being changed, an eyepiece unit having positive refractive power for enlarging and observing therethrough a spatial image formed by the objective lens unit, and an image erecting optical system for erecting an inverted spatial image formed by the objective lens unit. The forward group in the objective lens unit comprises a first lens having negative refractive power and a positive meniscus-shaped second lens having its convex surface facing the object side, and is designed to have negative refractive power as a whole.

Abstract: In a Keplerian zoom finder optical system including an objective lens unit having a magnification changing function and having positive refractive power, and an eyepiece unit having positive refractive power for enlarging and observing therethrough a real image formed by the objective lens unit, the objective lens unit has, in succession from the object side, a forward from the object side, a forward group comprising a negative first lens and a positive meniscus-shaped second lens having its convex surface facing the object side, and having negative refractive power as a whole, and a rearward group comprising a biconvex positive third lens and a positive meniscus-shaped fourth lens having its convex surface facing the image side, and having positive refractive power as a whole, the spacing between the forward group and the rearward group being changed to thereby accomplish finder magnification change. The objective lens unit is designed to satisfy the following conditions:-0.12<r.sub.7 /f.sub.4 <-0.