Abstract: A high-powered zoom lens system comprising at least three lens groups including a first positive lens group, a second positive lens group, and a negative lens group, arranged in this order as viewed from the side of an object to be photographed. The three lens groups are moved toward the object to be photographed during zooming from a wide-angle extremity to a telephoto extremity. The negative lens group satisfies the relationships defined by (1) 3.3<m.sub.Tn <6 and (2) 2.5<m.sub.Tn /m.sub.wn <4, wherein "m.sub.Tn " represents the lateral magnification of the negative lens group at the telephoto extremity, and "m.sub.wn " represents the lateral magnification of the negative lens group at the wide-angle extremity, respectively.

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: A zoom lens includes a positive first lens group, a positive second lens group, and a negative third lens group, in this order from the subject side. The first lens group consists of a negative first lens element, a positive second lens element and a positive third lens element in this order from the object side and satisfies the following relationships:4.3<m.sub.3T <61.7<f.sub.T /f.sub.1G <331<.nu..sub.1 <550<.nu..sub.2 -.nu..sub.1 <30where "m.sub.3T " represents the lateral magnification of the third lens group at the longest focal length position, "f.sub.T " represents the focal length of the entire lens system at the longest focal length position, "f.sub.1G " represents the focal length of the first lens group, ".nu..sub.1 " represents the Abbe number of the negative first lens element of the first lens group, and ".nu..sub.2 " represents the Abbe number of the positive second lens element of the first lens group.

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 finder system of a camera has an objective lens, an eyepiece lens and deflecting system. The deflecting system includes an erecting system positioned between the objective lens and the eyepiece lens. The finder system also includes an LCD panel that is located on an image plane of the objective lens with the LCD panel displaying information which is viewed through the eyepiece lens. A first polarizer is positioned between the objective lens and the LCD panel while a second polarizer is positioned between the LCD panel and the eyepiece lens. The first and second polarizers are arranged such that their transmission axes are perpendicular to each other. Further at least one optical component of the deflecting system is located between the first polarizer and the second polarizer.

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 shiftable lens system having front and rear lens groups, wherein a part or the whole of the rear lens group is shiftable in a direction perpendicular to the principal optical axis thereof.

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 camera viewfinder having a plurality of lens groups, wherein a photographing optical system of the camera is separate from the viewfinder. The viewfinder includes a parallax error compensating and diopter adjusting lens group which is one of the plurality of lens groups. The viewfinder further includes a guide member for guiding the compensating and adjusting lens group in a direction that intersects the optical axis of the viewfinder so as to move the lens group towards and away from the optical axis of the photographing optical system. In addition, there is provided an object distance detecting mechanism for detecting a distance of an object to be photographed, and a movement control mechanism for continuously moving the parallax error compensating and diopter adjusting lens group along the guide member in accordance with the object distance detected by the object distance detecting mechanism.

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 zoom lens system which includes a positive first lens group and a negative second lens group, arranged in this order from an object side so that a distance between the first and second lens groups is changed to alter the focal length. The first lens group includes a first negative sub-lens group, and a first positive sub-lens group. The first negative sub-lens group includes a first negative lens made of glass, and a second negative lens made of plastic. The first positive sub-lens group includes a positive third lens made of glass. The negative second lens group includes a positive fourth lens made of plastic, and a negative fifth lens made of glass lens, in this order from the object side. The zoom lens system satisfies the following relationships:SF1=(r.sub.1-1 +r.sub.1-2)/(r.sub.1-1 -r.sub.1-2).ltoreq.0;andSF2=(r.sub.2-1 +r.sub.2-2)/(r.sub.2-1 -r.sub.2-2)>0where SF1 designates the shaping factor of the first negative lens, SF2 the shaping factor of the second negative lens, and r.sub.

Abstract: A tilting lens system including a plurality of lens groups in which at least one lens group subsequent to a first lens group can be tilted about a predetermined point on a principal ray axis thereof.

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

Abstract: A real image 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 real image finder system of a camera has an objective lens, an eyepiece lens and deflecting system. The deflecting system includes an erecting system positioned between the objective lens and the eyepiece lens. The finder system also includes an LCD panel that is located on an image plane of the objective lens with the LCD panel displaying information which is viewed through the eyepiece lens. A first polarizer is positioned between the objective lens and the LCD panel while a second polarizer is positioned between the LCD panel and the eyepiece lens. The first and second polarizers are arranged such that their transmission axes are perpendicular to each other. Further at least one optical component of the deflecting system is located between the first polarizer and the second polarizer.

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: A real image type of finder optical system, provided separately from a photographing optical system. A real image is formed by an objective optical system and is observed through an ocular optical system. The objective optical system includes at least one lens that is made of synthetic resin and has at least one lens surface coated with an anti-reflection material.

Abstract: A real image type of view finder including a positive objective lens group, a positive condenser lens group, an image erecting optical system which erects an inverted image formed by the objective lens group and the condenser lens group, and an eyepiece lens group through which the erected image can be observed. The condenser lens group is spaced at a predetermined distance from an image forming plane in the direction of the objective lens group. The inverted image is formed on the image forming plane.