Abstract: A multiple-focal-length imaging device includes at least one image sensor positioned in one plane; and a plurality of image-forming optical systems through which a plurality of images at different magnifications are formed on a plurality of different image-forming areas on the image sensor.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, the positive third lens group remains stationary, and the negative first and positive second lens groups move along the optical axis of the zoom lens system. The negative first lens group includes at least one positive lens element which has a convex aspherical surface facing toward the image. Furthermore, the following conditions (1) and (2) are satisfied: 1.2<|f1/f2|<1.6  (1) 0.8<f3/f2<1.3  (2) wherein f1, f2 and f3 designate the focal length of the first, second and third lens groups, respectively.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. The negative first lens group includes a negative meniscus lens element having the convex surface facing toward the object, and the positive third lens group includes a positive biconvex lens element. Upon zooming, at least the negative first lens group and the positive second lens group are moved. A diaphragm is provided on the object side of the positive second lens group, and moves integrally therewith. The zoom lens system satisfies the following conditions: 0.25<R1/D1<0.55 . . . (1); 0.25<f2/TL<0.45 . . .

Abstract: A zoom lens system including a first to third lens groups, and zooming is performed by respectively moving the first to third lens groups. The zoom lens system satisfies the following conditions: 1.3<|f1/f2|<1.8   (1) 2.0<f3/fw<3.4   (2) 1.05<m3t/m3w<1.25   (3) wherein fw: the focal length of the entire the zoom lens system at the short focal length extremity; f1: the focal length of the first lens group; f2: the focal length of the second lens group; f3: the focal length of the third lens group; m3w: the magnification of the third lens group at the short focal length extremity, when an object at infinity is in an in-focus state; m3t designates the magnification of the third lens group at the long focal length extremity, when an object at infinity is in an in-focus state.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, the positive third lens group remains stationary, and the negative first and positive second lens groups move along the optical axis of the zoom lens system. The negative first lens group includes at least one positive lens element which has a convex aspherical surface facing toward the image.

Abstract: A zoom lens system including a first to third lens groups, and zooming is performed by respectively moving the first to third lens groups.

Abstract: The stereoscopic microscope includes a common close-up optical system that faces an object, a pair of zoom optical systems that form a pair of primary image, a pair of field stops, a pair of relay optical systems that relay the primary images to form a pair of secondary images, an inter-axis distance reducing element, an image taking device and an illuminating optical system. The object light rays incident on the close-up optical system form the primary images having predetermined parallax at the field stops through the zoom optical systems. The inter-axis distance reducing element reduces the inter-axis distance of the right and left light rays. The primary images are re-imaged by the relay optical systems as the secondary images on the adjacent regions on the single image taking surface of the image taking device, respectively.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and a positive third lens group, in this order from the object. Zooming is performed by moving the second lens group and the third lens group, and the zoom lens system satisfies the following conditions: 0.0<Fw/f1<0.15  (1) 0.75<|f2/f3|<1.0  (2) 1.65<LD/Ft<2.25  (3) wherein Fw designates the focal length of the entire lens system at the short focal length extremity; Ft designates the focal length of the entire lens system at the long focal length extremity; f1 designates the focal length of the first lens group; f2 designates the focal length of the second lens group; f3 designates the focal length of the third lens group; and LD designates the distance, at the short focal length extremity, from the most object-side surface of the first lens group to the most image-side surface of the third lens group.

Abstract: A photographing lens includes a front lens unit and a rear lens unit that are arranged in this order from the object side. The front lens unit comprises, in this order from the object side, a first lens element which is a positive meniscus lens having a convex surface facing the object side, a second lens element which is a positive meniscus lens having a convex surface facing the object side and a third lens element that is cemented to the second lens element. The third lens element is a negative meniscus lens having a convex surface facing the object side. The rear lens group comprises, in this order from the object side, a fourth lens element which is a positive meniscus lens having a convex surface facing the image side, a fifth lens element which is a negative meniscus lens having a concave surface facing the object side and a sixth lens element which is cemented to the fifth lens element. The sixth lens element is a positive meniscus lens having a convex surface facing the image side.

Abstract: A photographic lens comprising: a front lens group and a rear lens group that are arranged in order from the object side; wherein the front lens group comprises, in order from the object side, a first lens element which is a positive meniscus lens having a convex surface facing the object side, a second lens element which is a positive meniscus lens having a convex surface facing the object side, and a third lens element that is cemented to the second lens element, the third lens element being a negative meniscus lens having a convex surface facing the object side; wherein said rear lens group comprises, in order from the object side, a fourth lens element which is a positive meniscus lens having a convex surface facing the image side; a fifth lens element which is a negative meniscus lens having a concave surface facing the object side; a sixth lens element that is cemented to the fifth lens element, the sixth lens element being a positive meniscus lens having a convex surface facing the image side; and wher

Abstract: A projector in which light emitted from a light source is made incident upon a transmission type picture panel and is projected onto a screen through a projection lens system having a condenser lens and an imaging lens. The condenser lens and the imaging lens are relatively movable with respect to the transmission type picture panel in an optical axis direction. Thus, when a projection distance from the projection lens system to the screen is varied, both the condenser lens and the imaging lens are relatively moved, with respect to the transmission type picture panel, to adjust a focus of the emitted light on the screen. A focusing method for the projector is also provided.

Abstract: A projection lens assembly having an imaging lens group, including a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a Fresnel lens group having a positive refractive power and at least one Fresnel lens surface, in this order from the enlargement side. The projection lens assembly satisfies the relationships 1.4<f.sub.1 /f<2.8, and 1.5<f.sub.2 /f<6.0. In these relationships, f represents the focal length of the whole lens system, f.sub.1 the focal length of the first lens group, and f.sub.2 the focal length of the second lens group.

Abstract: A variable power projection lens is provided and includes, in order from an magnifying side (a screen side), a first lens group having positive power, a second lens group having negative power, a third lens group having positive power, and a fourth lens group having positive power. At least two lens groups of the first, second, and third lens groups are movable along the optical-axis direction to vary the image magnification and to focus, and the variable power projection lens satisfies the following condition:.vertline.f.alpha..vertline.>5fwwheref.alpha.: the synthetic focal length at the wide end from the first lens group to the third lens group; andfw: the focal length at the wide end of the overall lens system.

Abstract: A pupil conjugate-coupling device in a projecting optical system includes a first projection lens system which forms an intermediate image of an image indicating element, a second projection lens system which projects the intermediate image onto a screen, said first and second projection lens systems having optical axes intersecting at a predetermined angle, and an optical element having structural periodicity positioned between the first and second projection lens systems. The optical element has a positive power and a prism function for deflecting a bundle of rays transmitted through the first projection lens system towards the optical axis of the second projection lens system to thereby couple pupils of the first and second projection lens systems. The optical element is deviated from an intermediate image forming position by a predetermined offset in the optical axis direction thereof.

Abstract: A projector has projecting optical systems which include image formers and projecting lenses for projecting the formed images onto a screen. The optical axes of the projecting lenses are intersected with each other on or very near the surface of the screen. The image formers are arranged such that an image surface of each image former is coincident with the screen in accordance with Scheimpflug's rule.

Abstract: In an imaging apparatus, a magnified image of an object is formed on a predetermined plane through a plurality of lens groups. A plurality of filters are selectively inserted into the light path between the object and the predetermined plane. An optical device is provided in the imaging apparatus, in which the plurality of lens groups are driven as a unit along the optical axis while the positional relation among the respective lens groups are correspondingly changed, wherein at least one of the plurality of lens groups is independently driven along the optical axis. The plurality of lens groups are driven to move in accordance with a desired image magnification, and at-least-one of the plurality of lens groups is independently driven, depending upon the selected filter, so as to place the object image on the predetermined plane.

Abstract: An image combining and projecting apparatus having a plurality of light transmission type image panels through which light beams are transmitted, condenser lenses corresponding to the light transmission type image panels, a beam combining mechanism which combines beams transmitted through the image panels, and a projection lens through which beams are projected after being combined by the beam combining mechanism, wherein the condenser lenses are provided on the light outgoing side of the corresponding image panels. The apparatus further has a condenser lens adjusting mechanism for adjusting the positions of the condenser lenses.

Abstract: A magnifying projecting lens has a negative first lens group, a positive second lens group and a positive third lens group that is arranged in this order from a magnifying side. The lens groups are arranged so as to satisfy the following condition:fb/f>1.7,whereinfb equals a back focus when an object distance is .infin.f equals a focal length of the lens.

Abstract: A zoom lens system is disclosed in which a high zoom ratio of 2.5 or more, that is short in the overall lens length, that is composed of a smaller number of lens elements, that will experience less deterioration in performance due to manufacturing or assembly errors or less focus shift due to temperature or humidity changes, and which hence is suitable for use with a compact camera.

Abstract: A zoom lens system comprising, in order from the object side, a first lens group that includes at least three lens elements and that has a negative overall power and a second lens group that includes at least four lens elements, with the negative lens element of the greatest powre being cemented to the adjacent positive lens element, and that has a positive overall power. The zoom lens system is capable of changing its focal length by adjusting the distance between the first and second lens groups. The zoom lens system satisfies the specific conditions.