Abstract: A zoom eyepiece optical system, which is used with an objective optical system, includes a first lens group which is stationary with respect to the objective optical system, a negative second lens group which is movable upon zooming, a positive third lens group which is movable upon zooming, and a stationary positive fourth lens group, in this order from the objective optical system. Upon zooming from the long focal length extremity to the short focal length extremity of the zoom eyepiece optical system, the negative second lens group and the positive third lens group move away from each other, and an intermediate image is formed between the negative second lens group and the positive third lens group.

Abstract: An image separating device connected to a rigid endoscope has a Pechan prism to shift the optical axis of an objective optical system contained in the rigid endoscope, X- and Y-stages and a moving mechanism for moving the Pechan prism in a direction perpendicular to the optical axis of the objective optical system, and an enlarging optical system having an optical axis parallel with the optical axis of the objective optical system. As the Pechan prism is shifted, the image formed through the objective optical system is relatively shifted within its image plane, so that the image re-formed through a first image re-forming optical system is picked up by a first CCD camera without any decentering aberration, inclination relative to a direction perpendicular to the optical axis of the first image re-forming optical system, nor image rotation about the optical axis.

Abstract: A beam splitter for a digital camera splits light passed through a photographing lens into beams directed to a CCD and a finder optical system. The beam splitter includes at least one optical element provided with a beam splitting surface that is inclined with respect to an optical axis of the photographing lens, and a multi-layer film including a plurality of layers of dielectric materials is formed on the beam splitting surface. The multi-layer film is configured such that the beam splitting surface exhibits a substantially constant reflectivity at least for visible light that is incident on the beam splitting surface at any incident angle within a predetermined range.

Abstract: A zoom eyepiece optical system, which is used with an objective optical system, includes a first lens group which is stationary with respect to the objective optical system, a negative second lens group which is movable upon zooming, a positive third lens group which is movable upon zooming, and a stationary positive fourth lens group, in this order from the objective optical system. Upon zooming from the long focal length extremity to the short focal length extremity of the zoom eyepiece optical system, the negative second lens group and the positive third lens group move away from each other, and an intermediate image is formed between the negative second lens group and the positive third lens group.

Abstract: A telescopic zoom lens system has a minimum magnification thereof is more than 2, and includes a positive objective lens group, and a positive eyepiece lens group, in this order from the object. Further, a zooming lens group which is made moveable along the optical axis upon zooming is positioned on the side of the object with respect to the primary image forming plane of the objective optical system.

Abstract: A finder optical system for a single lens reflex camera is provided with a photographing optical system, a beam splitter for splitting light passed through the photographing optical system. First light deflected by the beam splitter forms a primary image at a position downstream from the beam splitter. Second light passed through the beam splitter is incident on a CCD. A relaying optical system is arranged on an optical path of the light deflected by the optical element to relay the primary image to form a secondary image. A reflection surface is arranged between the relaying optical system and an eyepiece optical system. The reflection surface deflects light, which is directed from the relaying optical system, toward the eyepiece optical system, to proceed in a direction parallel with an optical axis of the photographing optical system. The secondary image is formed between the reflection surface and the eyepiece optical system.

Abstract: In an optical viewer instrument with a photographing function, there is provided a telescopic lens system for observing objects, and a digital camera system including a solid-state image sensor and a photographing lens system associated with each other such that an object is formed as a photographed image on the solid-state image sensor through the photographing lens system. A manually-operable focussing mechanism is associated with the telescopic lens system and the photographing lens system such that the object is brought into focus through the telescopic lens system, and such that the object is brought into focus through the photographing lens system. Optical parameters are selected such that predetermined conditions are fulfilled, whereby the focussing of the telescopic lens system and the focusing of the photographing lens system can be suitably and properly performed by the focussing mechanism.

Abstract: In an optical viewer instrument with a photographing function, a telescopic lens system for observing an object and a digital camera system for photographing the object are housed in a casing. A manually-operable rotary wheel is rotatably provided in the casing such that a portion of the rotary wheel is exposed to the outside from the casing to bring the object into focus through the telescopic lens system. A display panel unit for displaying the object as a motion picture on a display screen thereof is mounted on the casing so as to be movable between a retracted position, where the display screen of the display panel unit is close to a wall surface of the casing, and a display position, where the display screen of the display panel unit is directed to the ocular-lens-system side of the telescopic lens system. The rotary wheel is arranged such that the exposed portion of the manually-operable rotary wheel is hidden behind the display panel unit when being at the retracted position.

Abstract: A telescope includes an erecting system having first, second, third and fourth reflecting surfaces from an object side, the first and second reflecting surfaces and the third and fourth reflecting surfaces facing each other at right angle, respectively. An objective lens located between the first and fourth reflecting surfaces has a positive refractive power to converge object light that is reflected by at least the first reflecting surface for forming an image. An eyepiece located between the fourth reflecting surface and an eye point, has a positive refractive power to magnify the image formed by the objective lens. The first reflecting surface is formed on a retractable mirror that can swing between a working position such that the first and second reflecting surfaces are perpendicular, and a retracted position such that a free end of the retractable mirror moves close to the second reflecting surface.

Abstract: A finder indication optical system, in which an indication device is provided, includes a correction surface provided in the finder indication optical system to correct an astigmatic difference thereof. The origin of the correction surface is defined on the optical axis; the optical axis defines an X-axis; the transverse direction of the correction surface, perpendicular to the X-axis, defines a Y-axis; the longitudinal direction of the correction surface, perpendicular to the X-axis, defines a Z-axis; the coordinates of the center of the correction surface are (&agr;,&bgr;); and the absolute value of curvature C in a section parallel with a X-Z plane, at the coordinates (y, z) of the correction surface, is |CZ(y, z)|. The correction surface is formed so that the absolute value |CZ(y, z)| of the curvature C increases as the absolute value of z at y=&agr; increases.

Abstract: An image separating device connected to a rigid endoscope has a Pechan prism to shift the optical axis of an objective optical system contained in the rigid endoscope, X- and Y-stages and a moving mechanism for moving the Pechan prism in a direction perpendicular to the optical axis of the objective optical system, and an enlarging optical system having an optical axis parallel with the optical axis of the objective optical system. As the Pechan prism is shifted, the image formed through the objective optical system is relatively shifted within its image plane, so that the image re-formed through a first image re-forming optical system is picked up by a first CCD camera without any decentering aberration, inclination relative to a direction perpendicular to the optical axis of the first image re-forming optical system, nor image rotation about the optical axis.

Abstract: A telescope or binoculars includes an erecting system having a plurality of reflecting surfaces. First and second reflecting surfaces and third and fourth reflecting surfaces respectively face each other at right angles. An intersection line between extended surfaces of the first and second reflecting surfaces is perpendicular to the intersection line between extended surfaces of the third and fourth reflecting surfaces. An objective lens is located between the second and third reflecting surfaces and converges object light that is reflected by the first and second reflecting surfaces for forming an image. An eyepiece is located between the fourth reflecting surface and an eye point to magnify the image formed by the objective lens.

Abstract: Disclosed is a prism having a light incident surface, a light emerging surface, and at least one light reflection surface. The light incident on the light incident surface is reflected, inside the prism, by the light reflection surface, and emerged from the light emerging surface. At least one light reflection surface has a reflecting surface which does not satisfy a total reflection condition. A reflection area is formed on the at-least-one light reflection surface by applying light reflecting material. The reflection-area corresponds to a portion on which a normal light is incident. Further, a portion of the-at least-one reflection surface other than the reflection area is formed to be a low-reflection area-which has a lower reflectance index than the reflection area.

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 front lens group having positive refractive power, and a rear lens group having negative refractive power. The rear lens group is capable of moving in a direction orthogonal to an optical axis to stabilize an image when the binocular is moved due to hand-held shaking of a user.

Abstract: A beam splitter for a digital camera splits light passed through a photographing lens into beams directed to a CCD and a finder optical system. The beam splitter includes at least one optical element provided with a beam splitting surface that is inclined with respect to an optical axis of the photographing lens, and a multi-layer film including a plurality of layers of dielectric materials is formed on the beam splitting surface. The multi-layer film is configured such that the beam splitting surface exhibits a substantially constant reflectivity at least for visible light that is incident on the beam splitting surface at any incident angle within a predetermined range.

Abstract: Disclosed is a prism having a light incident surface, a light emerging surface, and at least one light reflection surface. The light incident on the light incident surface is reflected, inside the prism, by the light reflection surface, and emerged from the light emerging surface. At least one light reflection surface has a reflecting surface which does not satisfy a total reflection condition. A reflection area is formed on the at-least-one light reflection surface by applying light reflecting material. The reflection-area corresponds to a portion on which a normal light is incident. Further, a portion of the-at least-one reflection surface other than the reflection area is formed to be a low-reflection area-which has a lower reflectance index than the reflection area.

Abstract: A finder indication optical system, in which an indication device is provided, includes a correction surface provided in the finder indication optical system to correct an astigmatic difference thereof. The origin of the correction surface is defined on the optical axis; the optical axis defines an X-axis; the transverse direction of the correction surface, perpendicular to the X-axis, defines a Y-axis; the longitudinal direction of the correction surface, perpendicular to the X-axis, defines a Z-axis; the coordinates of the center of the correction surface are (&agr;,&bgr;); and the absolute value of curvature C in a section parallel with a X-Z plane, at the coordinates (y, z) of the correction surface, is |CZ(y, z)|. The correction surface is formed so that the absolute value |CZ(y, z)| of the curvature C increases as the absolute value of z at y=&agr; increases.

Abstract: A real image type finder optical system includes, in order from the object side, an objective optical system, a first prism, a second prism, and an eyepiece lens. The first prism includes a first face as an entrance surface confronting the exit plane of the objective optical system, a second face making an angle of 22.5° with respect to this first face and a third face for transmitting the finder optical axis bent in order by the second face and the first face. The second prism includes a first face as an entrance surface confronting the third face of the first prism with a space therebetween, a second face opposed to the first face so as to bend the finder optical axis toward the object side within a horizontal plane, a third face for turning the finder optical axis bent in order by the second face and the first face to a direction generally coaxial with the eyepiece lens and a fourth face for transmitting the optical axis turned from the third face.

Abstract: A negative ocular having a positive eye-side lens element positioned on the side of the user's eye and a positive field lens element positioned on the side of the object whereby an intermediate image formed by an objective lens system is formed between the eye-side lens element and the field lens element, and whereby the eyepiece lens system satisfies the following conditions: 0.8<L(1+S)/{f1(P+S)}<1.05   (1) 0.5<S(1—1/P)/(1+S)   (2) wherein S=&ngr;1/&ngr;2; P=f2/f1; f1 designates the focal length of the eye-side lens element; f2 designates the focal length of the field lens element; &ngr;1 designates the Abbe number of the eye-side lens element; &ngr;2 designates the Abbe number of the field lens element; and L designates the distance between the principal points of the field lens element and the eye-side lens element.

Abstract: A finder optical system for a single lens reflex camera is provided with a photographing optical system, a beam splitter for splitting light passed through the photographing optical system. First light deflected by the beam splitter forms a primary image at a position downstream from the beam splitter. Second light passed through the beam splitter is incident on a CCD. A relaying optical system is arranged on an optical path of the light deflected by the optical element to relay the primary image to form a secondary image. A reflection surface is arranged between the relaying optical system and an eyepiece optical system The reflection surface deflects light, which is directed from the relaying optical system, toward the eyepiece optical system, to proceed in a direction parallel with an optical axis of the photographing optical system. The secondary image is formed between the reflection surface and the eyepiece optical system.