Abstract: A real image type finder optical system comprising, in order from the object side, an objective optical system of non-telecentric system, a first prism having a wedge angle of 3°, a second prism, a third prism, and an eyepiece lens. The second prism has a first face as the entrance surface in contact with the back surface of the first prism, a second face forming an angle of 22.5° with respect to the first face and a third face for transmitting the optical axis bend by these second face and first face. The third prism has a first face as the entrance surface spaced in parallel from and confronting the third face of the second prism, a second face forming 45° with respect to the first face in order to bend the optical axis toward the object side at an angle of 90° within a horizontal plane, and a third face formed as roof faces for bending the optical axis bent by the second face toward the first face at an angle of 45° within a horizontal plane.

Abstract: A variable-power eyepiece optical system, which is used in combination with an objective optical system, includes a negative first lens group, a second lens group having a positive first sub lens group and a positive second sub lens group, and a positive third lens group, in this order from the objective optical system. The first lens group, and the first and second sub lens groups of the second lens group are made moveable along the optical axis upon variable power, while the third lens group is made immoveable. At the time of variable power, the first sub lens group and the second sub lens group move independently of each other in a direction opposite to the direction along which the first lens group moves, and thereby the resultant power of the first and second sub lens groups is varied.

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 group having positive refractive power, a second lens group having negative refractive power and a third lens group having positive refractive power. The second lens group and/or the third lens group is capable of moving in a direction perpendicular to an optical axis to stabilize an image. The objective optical system satisfies the following conditions: (1) 0.1<d12/f0 (2) 0.7<f0/f1<3.0 where, d12 is a distance between the first lens group and the second lens group, f0 is the focal length of the objective optical system, and f1 is the focal length of the first lens group.

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 binocular is provided with a pair of telescopic optical systems. Each of the pair of telescopic optical systems has an objective lens system, an erecting optical system, and an observing optical system. The erecting optical system of each of the telescopic optical systems may be a type I or type II Porro prism, which is divided into two sub prisms respectively have two reflection surfaces. First and second hand vibration compensation mechanism is provided: (a) between the objective lenses and erecting optical systems; and (b) between the first sub prisms and the second sub prisms.

Abstract: A binocular is provided with a hand-vibration compensation system. The hand-vibration compensation system includes an arm member which rotatable about a rotation axis extending in parallel with the optical axes of the pair of telescopic optical systems of the binocular. Compensation lenses for shifting images are held at the end portions of the arm. It should be noted that the rotation axis of the arm is located between the optical axes of the pair of telescopic optical systems, and more importantly, the arm is substantially equally balanced at the rotation axis thereof. The arm is driven to rotate about the rotation axis by an actuator in accordance with a hand-vibration applied to the binocular.

Abstract: Disclosed is an observation optical system such as a binocular. A telescopic optical system of the observation optical system is provided with a plurality of optical elements, which are arranged such that the observation optical system has a first optical axis horizontally extending and a second optical axis vertically extending when the binocular is held horizontally by a user. The observation optical system is further provided with first and second compensation optical systems that are movable to shift optical paths of light passed through the first and second compensation optical systems to compensate trembling of image due to hand vibration applied to the observation optical system. The compensation optical systems are constituted and arranged such that movement thereof will not be affected by the gravity.

Abstract: A binocular is provided with a pair of telescopic optical systems. Each of the pair of telescopic optical systems has an objective lens, an erecting system, a compensation lens and an observing optical system. The erecting system of each of the telescopic optical systems is divided into two sub prisms, a vertically extending optical axis is defined therebetween. The compensation lens is located between the first and second sub prisms such that it is movable in a horizontal plane by a driving mechanism. As the compensation lens moves, an optical path of light passed therethrough changes. Accordingly, by driving the compensation lens in accordance with the hand-vibration, trembling of the image can be compensated.

Abstract: Provided is a hand-vibration compensation system for compensating trembling of images due to a hand-vibration applied to a binocular having a pair of telescopic optical systems. The hand-vibration compensation system includes first and second compensation optical systems respectively provided in the pair of telescopic optical systems. The optical axes of the pair of telescopic optical systems intersect the first and second compensation optical systems, respectively. The compensation system further includes a driving system that moves at least one optical element included in each of the first and second optical systems in opposite directions within a plane perpendicular to the optical axes of the pair of telescopic optical systems.

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 binocular is provided with a pair of telescopic optical systems. Each of the pair of telescopic optical systems has an objective lens, a pair of positive and negative compensation lenses, an erecting system, and an observing optical system. The negative compensation lens of the right telescopic optical system and the positive compensation lens of the left telescopic optical system are held by a rotatable first frame. The positive compensation lens of the right telescopic optical system and the negative compensation lens of the left telescopic optical system are held by a rotatable second frame. The first and second frames are driven in the opposite directions to each other such that the vibration of the image can be compensated.

Abstract: An eyepiece including a positive first lens element, a negative second lens element, a positive third lens element and a positive fourth lens element is provided. The first, second, third, and fourth lens elements are spaced from one another and arranged in this order from an object side. At least one of the four lens elements is a plastic lens with at least one aspherical surface satisfying the relationships defined by;d.sup.2 x/dh.sup.2 .ltoreq.{c/(1-0.sub.+ 5c.sup.2 h.sup.2).sup.3/2 }: when c >0; andd.sup.2 x/dh.sup.2 .gtoreq.{(c/1-0.sub.+ 5c.sup.2 h.sup.2).sup.3/2 }): when c<0;wherein"c" represents paraxial curvature;"x" represents sag amount; and,"h" represents a height from an optical axis.

Abstract: An eyepiece system includes a single positive lens and a cemented lens assembly having a positive biconvex lens and a negative lens cemented thereto, in this order from the object side. The eyepiece satisfies the relationships defined by d<0.3f, and f.sub.1 >1.5f, wherein "d" represents a distance between the single positive lens and the cemented lens assembly, "f" a focal length of the whole lens system, and "f.sub.1 " a focal length of the single positive lens.

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: 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: A wedge prism unit is positioned on the optical axes of the objective optical systems of two telescope systems of a binocular. The wedge prism unit includes a front wedge prism element and a rear wedge prism element that are oppositely oriented. When rotated by equal amounts in opposite directions, the wedge prism elements deflect incident light in a direction perpendicular to the rotation axis. The wedge prism unit is placed along the objective optical axes of the binocular, oriented to deflect the visual field to compensate for vibration. A control circuit controls a single motor according to a vibration sensor to deflect the visual field in a direction opposite to the vibration. The rotation axis is either within or outside of an imaginary plane containing both of the optical axes.

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 double Porro prism having an incident surface, an exit surface, and a plurality of reflecting surfaces for internally reflecting light rays from the incident surface to the exit surface. The plurality of reflecting surfaces having a final reflecting surface that is positioned near the exit surface. The double Porro prism also has a ghost preventing surface that is formed between a ridge of the final reflecting surface and a ridge of the exit surface.

Abstract: A telescope includes a master telescope whose aberration has been independently corrected and which has an objective lens and an ocular lens. A rear conversion lens is provided on the image side of the objective lens of the master telescope and is made of a single lens having a concave surface that faces an object side. The rear conversion lens meets the requirements defined by the following relationships: f.sub.o '/f.sub.o >1 and 0.5<(dx.sub.2 /dh.sub.2)/(dx.sub.1 /dh.sub.1)<1.3, wherein "f.sub.o " represents the focal length of the objective lens of the master telescope; "f.sub.o '" represents the resultant focal length of the objective lens of the master telescope and the rear conversion lens; "dx.sub.1 /dh.sub.1 " represents an inclination of an incident surface of the rear conversion lens at an incident point thereof, upon which light is incident at a height h.sub.1 ; "dx.sub.2 /dh.sub.