Abstract: An imaging device has a zoom lens system comprising a plurality of lens units and forming an optical image of an object so as to be continuously and optically zoomable by varying a distance between the lens units; and an image sensing element converting the optical image formed by the zoom lens system into an electric signal, wherein the zoom lens system comprises from the object side: a first lens unit having positive optical power as a whole and including a reflecting surface that bends a luminous flux substantially 90 degrees; a second lens unit having negative optical power and disposed with a variable air space from the first lens unit; a third lens unit having positive optical power and disposed with a variable air space from the second lens unit; a fourth lens unit having positive optical power and disposed with a variable air space from the third lens unit; and a fifth lens unit disposed with a variable air space from the fourth lens unit, and wherein zooming is optically performed by varying the air

Abstract: This invention relates to a microscope having an infinity-corrected objective and providing a flat field of view.

Abstract: A zoom lens having five lens groups arranged in succession. The zoom lens is configured such that when zooming from a short focal length end toward a long focal length end, the second lens group lens moves toward the third lens group and the fourth lens group moves toward a side of the third lens group, and the fifth lens group corrects the zooming and a shift in a position of an imaging plane of the zoom lens caused by movement of the third lens group and the fourth lens group.

Abstract: The present invention provides a high-performance, thin wide-angle lens suitable for imaging elements with high pixel counts. The wide-angle lens includes, from an object side to an image plane side: a first lens group including a first lens having a negative refractivity and a second lens having a positive refractivity; and a second lens group including a third lens having a negative refractivity, a fourth lens having a positive refractivity, and a fifth lens having a positive refractivity. The fourth lens is bonded to the third lens. The fifth lens is formed with at least one of its convex surfaces being an aspherical surface.

Abstract: A collimator lens comprises, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power. The second and third lenses are cemented together. One of the second and third lenses has a negative refracting power, whereas the other has a positive refracting power. The collimator lens further satisfies Bƒ/ƒ>0.6, where Bf is the back focus of the whole lens system, and f is the focal length of the whole lens system.

Abstract: A zoom lens includes a first lens band having a positive focal length, a second lens band having a negative focal length, and at least third to fifth lens bands having positive focal lengths. An aperture diaphragm is located in the vicinity of the third lens band. When magnification i.e., zooming is performed from short to long focal point ends, the second lens band smoothly moves toward the third lens band and the fourth lens band simultaneously moves from the fifth lens band side toward a long focal point end so as to share a magnification function together with the second lens band.

Abstract: A variable focal length optical system of reducing size and increased zoom ratio is provided. According to one aspect. at least three lens groups, in order from an object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. When a state of lens group positions is changed from a wide-angle end state to a telephoto end state, each lens group moves to the object side such that an air gap between the first lens group G1 and the second lens group G2 increases, and an air gap between the second lens group G2 and the third lens group G3 decreases. An aperture diaphragm is arranged between the first lens group G1 and the third lens group G3. The second lens group G2 is arranged in the vicinity of the aperture diaphragm and has a positive lens having double aspherical surfaces. Particular conditions are satisfied.

Abstract: An optical projection lens system comprising one lens with an aspherical surface and comprising a first bulge followed by a first waist followed by a second bulge, wherein the diameter of the second bulge is smaller than the diameter of the first bulge.

Abstract: A collimator lens comprises, successively from a parallel luminous flux side, a first lens having a positive refracting power, second and third lenses having a negative composite refracting power, a fourth lens having a positive refracting power, and a fifth lens having a positive refracting power. The second and third lenses are cemented together. One of the second and third lenses has a negative refracting power, whereas the other has a positive refracting power. The collimator lens further satisfies Bƒ/ƒ>0.6, where Bf is the back focus of the whole lens system, and f is the focal length of the whole lens system.

Abstract: An imaging lens comprises, successively from an object side, a positive first lens L1 having a convex surface directed onto the object side, a negative second lens L2 having a concave surface directed onto an image side, a third lens L3 of a positive meniscus form having a convex surface directed onto the object side, a fourth lens L4 of a positive meniscus form having a convex surface directed onto the image side, a negative fifth lens L5 having a concave surface directed onto the object side, and a positive sixth lens L6 having a convex surface directed onto the image side, the first lens L1 and the second lens L2 being cemented to each other, the fifth lens L5 and the sixth lens L6 being cemented to each other, the imaging lens satisfying the following conditional expressions: 0.01<d6/f<0.17 0.9<f3/f<1.8 −0.4<f/f12<0.4 0.51<f34/f<0.72 1.15<v1/v2<1.

Abstract: A color image readout lens usable within a magnification range from −0.6X to −1.7X comprises, successively from the object side, a first lens group G1 comprising by a lens having a positive refracting power with a convex surface directed onto the object side, a second lens group G2, comprising by a cemented lens, composed of a biconvex lens and a biconcave lens, having a negative refracting power as a whole with a convex surface directed onto the object side, a third lens group G3, comprising a cemented lens, composed of a biconcave lens and a biconvex lens, having a negative refracting power as a whole with a convex surface directed onto an image side, a fourth lens group G4 comprising a positive lens with a convex surface directed onto the image side, and a fifth lens group G5 comprising a negative meniscus lens with a stronger concave surface directed onto the object side. The color image readout lens further satisfies predetermined conditional expressions.

Abstract: A zoom lens system has the first to fifth lens units from the object side. Refractive powers of the first to fifth lens units are positive, negative, negative, positive, negative, respectively. During zooming, the distances between the lens units are varied. Image blur compensation is made by parallel decentering the second lens unit. When f2 is the focal length of the second lens unit, f5 is the focal length of the fifth lens unit, and fw is the focal length of the entire lens system, then the following conditions are satisfied. 0.2<|f2/fw|<4.0 0.2<|f5/fw|<0.

Abstract: A zoom lens system with an anti-vibration function, which is provided with, in order from the object end: a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power, and whose focal length at the wide-angle end is shorter than the diagonal width of the image plane of the zoom lens system, at least one lens group selected from the first lens group and the fifth lens group moves toward the object end and all of the distances between each of the lens groups are changed when zooming from the wide-angle end to the telephoto end. At least one lens group selected from the second, third, and fourth lens groups moves in a direction substantially perpendicular to the optical axis of the zoom lens system when preventing vibration.

Abstract: A projection lens for use with LCD panels is provided. The lens has a first lens unit which has a positive power and a second lens unit which has a negative power. The first lens unit contains at least four lens elements, namely, a positive first lens element, a negative second lens element which is composed of a high dispersion material, a third lens element of weak optical power, and a positive fourth lens element of strong optical power. The projection lens achieves a correction of chromatic aberration on the order of about a quarter of pixel for large LCD panels having pixels on the order of 200 microns.

Abstract: An aberration-controllable optical system has a large angle of view and is capable of continuously varying spherical aberrations from negative values to positive values, including a point at which a sharp image can be produced. A master lens group includes a first sub lens group having a positive refractive power, a second sub lens group having a negative refractive power, and a third sub lens group having a positive refractive power in this order from the object side of the system. The converter lens group includes a positive lens element and a negative lens element in this order from the object side. The on-axis distance of the air gap which is formed between the positive lens element and the negative lens element can be controlled to mainly change the spherical aberrations in this system. When f.sub.m is a master lens group focal length and f.sub.C is a converter lens group focal length, the aberration-controllable optical system satisfies a condition:-1<f.sub.M /f.sub.C <0.

Abstract: A projection lens system has a wide angle with small value for back focus, superior telecentric characteristics, and small distortion. The projection lens system includes a first lens group having a negative refractive power and a second lens group having a positive refractive power. The focal length of the entire system, the focal length of the first lens group and the focal length of the second lens group satisfy conditional formulas.

Abstract: Eyepiece lenses of wide visual field, one of which has a field angle of 75.degree. or wider, and another one of which has a field angle of 60.degree. with a smaller number of constituent lenses than the former has. One of these eyepiece lenses comprises, in the order from the light incidence side, a first lens unit of negative refractive power, a second lens unit of positive refractive power in the meniscus form concave toward the light incidence side, a third lens unit of meniscus form concave toward the light incidence side, a fourth lens unit of positive refractive power, and a fifth lens unit of positive refractive power in the meniscus form convex toward the light incidence side. A middle image plane lies within the second lens unit, or in a space between the second and third lens units.

Abstract: In a variable focal length optical system which has, in succession from an object side, a first lens unit G1 having a positive refractive power, a second lens unit G2 having a negative refractive power, a third lens unit G3 having a positive refractive power, a fourth lens unit G4 having a positive refractive power, and a fifth lens unit G5 having a negative refractive power, when the focal length is varied from the maximum wide-angle state to the maximum telephoto state, at least the fifth lens unit G5 moves toward the object side, so that a first variable air gap between the first lens unit G1 and the second lens unit G2 increases, a second variable air gap between the second lens unit G2 and the third lens unit G3 decreases, a third variable air gap between the third lens unit G3 and the fourth lens unit G4 increases, and a fourth variable air gap between the fourth lens unit G4 and the fifth lens unit G5 decreases, the second lens unit G2 at least has a negative sub lens unit G21 which is disposed at a po

Abstract: A high-performance taking lens system suitable for a lens shutter type camera, which is capable of displaying superior optical performance as far as the edges of film image field with minimal deterioration of the performance despite a simple arrangement. The taking lens system has a front lens unit including at least one positive lens (G1) and at least one negative lens (G2) whose image-side surface has a higher curvature than that of the object-side surface thereof, and a rear lens unit disposed behind the front lens unit and including a doublet (G3) which consists of one positive lens and one negative lens and which has a positive refractive power, and a positive lens (G4). The lens surface of the doublet (G3) that is the closest to the image side is concave toward the image side. The intermediate lens surface of the doublet (G3) is convex toward the image side. The negative lens (G2) is preferably a meniscus negative lens having a concave surface directed toward the image side.

Abstract: A zoom lens includes a first lens group having a positive refracting power, a second lens group having a negative refracting power, a third lens group having a positive refracting power, a fourth lens group having a negative refracting power, and a fifth lens group having a positive refracting power in this order from the object side in order to perform zooming by varying the distance between the lens groups, the fifth lens having at least one positive lens and a cemented lens which has a negative refractive index as a whole, its positive lens being cemented to its negative lens, and the cemented surface being convex on the image side.

Abstract: A zoom lens incorporating a vibration-proofing function comprises, sequentially from an object side, a first lens group G.sub.1 having a positive refracting power; a second lens group G.sub.2 having a negative refracting power; a third lens group G.sub.3 having a negative refracting power; a fourth lens group G.sub.4 having a positive refracting power; and a fifth lens group G.sub.5 having a negative refracting power. The lens groups move so that when varying a magnifying power from a wide-angle end to a telephoto end, a spacing between the first and second lens groups G.sub.1, G.sub.2 increases; a spacing between the second and third lens groups G.sub.2, G.sub.3 changes linearly or non-linearly; and a spacing between the fourth and fifth lens groups G.sub.4, G.sub.5 is reduced. The zoom lens comprises a shift means for moving one of the third and fourth lens groups G.sub.3, G.sub.4 perpendicularly across the optical axis.

Abstract: A projection TV lens (60) includes first (64), second (66), third (70), and fourth (72) element-groups counted in numerical order and arranged on a common optical axis (62). The first, third, and fourth groups each include at least one lens element. The first and third group has positive power and the fourth group has negative power. The second group includes a first lens element (67) having negative power and having a graded refractive index.

Abstract: A projection lens has a five-group structure, in which a first-group lens is a positive lens, a second-group lens is a negative lens, third- and fourth-group lenses are respectively positive lenses, and a fifth-group lens is a negative lens. The projection lens has a half view angle of 34.degree. or greater, and satisfies the following conditions: 0.04<d.sub.4 /f.sub.0 <0.08, 0.2<.phi..sub.1 <0.9, -0.6<.phi..sub.2 <0, 0.7<.phi..sub.3 <1.0, 0<.phi..sub.4 <0.5, and -1.36<.phi..sub.5 <-0.6, where: f.sub.0 : focal distance of the overall system, d.sub.4 : on-axis interval between the second-group lens and the third-group lens, .phi..sub.1 : power of the first-group lens, .phi..sub.2 : power of the second-group lens, .phi..sub.3 : power of the third-group lens, .phi..sub.4 : power of the fourth-group lens, and .phi..sub.5 : power of the fifth-group lens, (where .phi..sub.1 -.phi..sub.5 are respectively values obtained when the optical power of the overall system is set to 1).

Abstract: A zoom lens of five group construction utilizing an inner focus system. The zoom lens includes a first lens group G1 having a positive refracting power, a second lens group G2 having a negative refracting power, a third lens group G3 having a negative refracting power, a fourth lens group G4 having a positive refracting power and a fifth lens group G5 having a negative refracting power, which are arranged in this order from an object side, and the distances among the respective lens groups are selectively varied to effect the desired zooming operation. During close-up photographing, the second lens group G2 is moved along an optical axis to effect the desired focusing.

Abstract: In a projection lens device having at least two plastic lenses for magnification-projecting an original image displayed on a display screen onto a screen, one of the two plastic lens is convex at a center thereof toward the screen and concave at a periphery thereof, and the other lens has a weak positive refractive power toward the screen at a center thereof and a stronger positive refractive power at a periphery thereof. A variation of a lens power due to a change of a surrounding environment is cancelled out by the concave shape at the periphery of the one lens and the positive refractive power at the periphery of the other lens.

Abstract: In a zoom lens apparatus having a lens component which is movable for variation of image magnification, a lens component to compensate for the shift of focus caused by the variation of the image magnification and which is movable to bring an object to be photographed into focus, and a device for driving and positioning each of the lens components, there is provided a controller to control the device. The controller has a position table for each of the lens components and a memory to store the actual positions of the lens components. The controller compares each of the actual positions of the lens components stored in the memory with the position table, based on a signal for a desired magnification so that the zoom lens can focus on a predetermined image plane.

Abstract: The present invention provides a focal length changeable lens system which comprises a master lens group of a positive refractive power having at least one negative lens element made of a synthetic resin material; and a rear conversion lens group of a negative refractive power retractably arranged on the image side of the master lens group and having at least one positive lens element made of a synthetic resin material, in order to well compensate the change of back focal length of the lens system due to the change in temperature thereof without increasing the cost of the lens system.