Abstract: There is provided a subminiature imaging optical system installed in a mobile telecommunication terminal or a PDA, or used in a surveillance camera or a digital camera. The subminiature imaging optical system including: first, second, third and fourth lenses sequentially positioned from an object side to an image side, the first lens having positive refractive power, the second lens having negative refractive power, the third lens having negative refractive power, and the fourth lens having positive refractive power, wherein each of the third and fourth lenses has at least one aspherical surface. The subminiature imaging optical system corrects chromatic aberration superbly to reduce color fringing significantly, thereby achieving high resolution and compactness as well.

Abstract: There is provided a subminiature imaging optical system installed in a mobile telecommunication terminal or a PDA, or used in a surveillance camera or a digital camera. The subminiature imaging optical system including: first, second, third and fourth lenses sequentially positioned from an object side to an image side, the first lens having positive refractive power, the second lens having negative refractive power, the third lens having negative refractive power, and the fourth lens having positive refractive power, wherein each of the third and fourth lenses has at least one aspherical surface. The subminiature imaging optical system corrects chromatic aberration superbly to reduce color fringing significantly, thereby achieving high resolution and compactness as well.

Abstract: A compact and high-performance bright wide-angle zoom lens comprising, in order from the object side, a front group having a negative refractive power and a rear group having a positive refractive power, with a stop diaphragm being disposed between the front and rear groups. The front group, stop diaphragm and rear groups are capable of independent mechanical movement in response to a change in the focal length of the overall system. The rear group having a positive refractive power is composed, in order from the object side, of a positive lens unit, a negative lens unit, and a positive lens unit, with a lens element having a refractive index gradient profile along the optical axis being disposed in the positive lens unit on the image side of the rear group.

Abstract: A photographic lens with a large aperture ratio comprises a plurality of lens elements brighter than F 1.5 and having a total covering power of at least 40.degree., with at least one of the lens elements being capable of passing an entire luminous flux focusing on a center of an image plane through at least 80 percent of a lens aperture thereof, and given a monotonous refractive index variation in the direction of an optical axis of the lens.

Abstract: An optical system for a TTL automatic focusing video camera in which a beam splitter employed in the optical system is formed of at least two totally reflecting surfaces disposed on opposite sides of an optical axis of a main image pickup lens forming an angle with respect thereto of 90.degree. in the lateral direction and 45.degree. in the longitudinal direction., An abberation correction lens is arranged on opposite sides of the optical axis form the main image pickup lens. A light beam reflected and converged by a totally reflecting surface provided at a rear of the aberration correction lens is allowed to pass by the totally reflecting surfaces of the beam splitter to reach the automatic focusing sensor.

Abstract: An adapter for connecting an interchangeable lens, such as a lens which is ordinarily intended for use with a single-lens reflex camera, for which the distance from the rear surface on the lens to a focal plane is relatively great, to a camera body, such as a video camera body, for which the distance from the front surface of the lens mount to a focal plane is relatively small. The adapter includes a diaphragm, which is used in place of the diaphragm of the interchangeable lens, and an electric motor for controlling the aperture value provided by the diaphragm. The aperture data supplied by the interchangeable lens is transmitted to the camera body as electrical data, which is preferably produced with a variable resistor or the like. Contacts are provided on the casing of the adapter for transmitting data to the camera body and receiving an operating signal for the motor from the camera body.

Abstract: An ultracompact telephoto eight-group ten-element or eight-group eleven-element lens comprises, in order from an object, a front four-group four-element lens group including a first positive lens having a surface of a smaller radius of curvature directed toward the object, a second positive lens having a surface of a smaller radius of curvature directed toward the object, a third double-concave lens, and a fourth positive-meniscus lens having a surface of a smaller radius of curvature directed toward the object, an intermediate three-group five-element lens group including a compound lens composed of a fifth negative lens and a sixth double-convex lens, a compound lens composed of a seventh negative lens and an eighth double-convex lens, and a ninth negative lens having a surface of a smaller radius of curvature directed toward the object, and a rear lens group including a single tenth positive lens or a positive compound lens composed of a tenth positive lens and an eleventh negative lens.

Abstract: A zoom lens comprising, in order from the object, 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 and a fourth lens group having a positive refractive power. The first through fourth lens groups are independently moved in an axial direction to vary the overall focal length. The zoom lens meets the following conditions:(1) 0.25F.sub.W <F.sub.I <0.45F.sub.W(2) 1.65<n.sub.IV(3) 1.2f.sub.BW <f.sub.BT <0.95f.sub.BMwhere F.sub.W is the overall focal length at the minimum end,F.sub.I is the focal length of the first lens group,n.sub.IV is the average refractive index, at d-line, of the lens elements constituting the fourth lens group,f.sub.BW and f.sub.BT are the backfocuses at the minimum and maximum ends of the overall focal length, respectively, andF.sub.BM is the backfocus at the intermediate end of the overall focal length.

Abstract: A zoom lens system having, in order from the object side, a first lens group with a positive focal length, a second lens group with a negative focal length, a third lens component with a negative focal length and a fourth lens group with a positive focal length. The second lens group and third lens component are moved along the optical axis to achieve variation in the overall focal length and correction for focus movement. The first lens group includes one negative lens and at least two positive lenses, the second lens group includes, in order from the object side, a negative lens, a negative lens and a positive lens, the third lens component includes at least one negative lens, and the fourth lens group includes an optical path separation prism, and, in order from the object side, at least three positive lenses, at least two negative lenses and at least two positive lenses.

Abstract: A zoom lens comprising a first lens component having a positive refractive power, a second lens component having a negative refractive power, a third lens component having a negative refractive power, and a fourth lens component having a positive refractive power, the first through fourth lens components being arranged in order from an object.

Abstract: A zoom lens system in which aberration degradation due to focusing to a closer position, particularly a rapid increase in distortion of the focused image at the peripheral image field, is well compensated for. The lens system includes, from the object side, a first convergent lens component, a second convergent lens component, either a third convergent or divergent lens component and a fourth convergent lens component with the second and third components being movable for zooming. An afocal region is provided either in the space between the third and fourth lens components or within the fourth lens component.

Abstract: A rear stop diaphragm type zoom lens is disclosed. The zoom lens is composed, in order from the object side, of a first lens group as a whole having a negative refractive power and consisting of two negative lenses and a positive lens and a second lens group as a whole having a positive refractive power and consisting of two or three positive lenses, a negative lens and one or two lenses including at least one positive lens. An aerial space between the lens groups is varied to thereby vary the magnification, and a stop diaphragm is disposed behind the overall lens system with the stop diaphragm being maintained at a constant position with respect to the focusing surface during variation of magnification.

Abstract: A high performance compact wide angle zoom lens, composed, in order from the object side, of a divergent front lens group and a convergent rear lens group, wherein the front and rear lens groups are moved mechanically to thereby vary the overall focal length. The front lens group being composed, in order from the object side, of a first lens including a negative meniscus lens convex to the object, a second lens including a positive biconvex lens, a third lens including a negative meniscus lens convex to the object, a fourth lens including a negative lens and a fifth lens including a positive lens. The rear lens group being composed of a sixth lens including a positive lens, a seventh lens including a positive meniscus lens convex to the object, an eighth lens including a biconvex positive lens, a ninth lens including a biconcave negative lens, a tenth lens including a positive lens and an eleventh lens including a positive lens.

Abstract: A high performance zoom lens including, in order from the object side, a convergent first lens group including a cemented lens composed of a negative meniscus lens having a surface of greater curvature on the image side and a first positive meniscus lens having a surface of greater curvature on the object side and a second positive meniscus lens having a surface of greater curvature on the object side, a divergent second lens group including a negative meniscus lens having a surface of greater curvature on the image side, a biconcave lens and a positive meniscus lens having a surface of greater curvature on the object side, a convergent third lens group including a biconvex lens and a convergent fourth lens group including a cemented lens composed of a biconvex lens and a biconcave lens, a cemented lens composed of a negative meniscus lens having a surface of greater curvature on the image side and a biconvex lens, and a negative meniscus lens having a surface of greater curvature on the object side.

Abstract: A compact zoom lens covering a range from standard to telephoto and having a high zoom ratio of approximately four adapted for use with 35 mm SLR cameras. The zoom lens system includes a first convergent lens group, a divergent lens group and a second convergent lens group in that order from the object. The first convergent lens group includes three lens components including at least one negative lens component, the divergent lens group is composed of at least three lens components including at least one positive lens component while the second convergent lens group includes at least two negative and two positive lens components with the last lens component being a negative lens the surface of smaller radius of curvature of which is directed to the object. The first and second convergent lens groups may be either rigidly coupled to be movable together or movable independently from one another to vary the overall focal length of the zoom lens system.

Abstract: A high performance telephoto lens having a small telephoto ratio including eight lenses disposed in seven lens groups in front, intermediate and rear groups. The front lens group is composed of, in order, a positive lens having two curved surfaces with the surface of greater absolute value of curvature disposed on the object side, a positive meniscus lens having its convex surface disposed toward the object, a negative biconcave lens having the surface of greater absolute value of curvature disposed toward the image side, a positive meniscus lens having a convex surface directed toward the object. The intermediate lens groups includes two cemented lenses one of which is a negative biconcave lens disposed on the object side and a positive lens disposed on the image side.

Abstract: A compact standard zoom lens having a high performance, composed, in order from the object side, of a front lens group being a divergent lens group and a rear lens group being a convergent lens group. Both lens groups are mechanically movable to vary the focal length. The divergent lens group is composed, in order from the object side, of a first positive lens, a second double concave negative lens and a third positive meniscus lens convex on the object side. The convergent lens group is composed of less than five positive lenses and one negative lens. The zoom lens satisfies the following conditions:0.7.vertline.r.sub.3 .vertline.<.vertline.r.sub.2 .vertline.<0.95.vertline.r.sub.3 .vertline.r.sub.2, r.sub.3 <0 (1)n.sub.2 >1.80 (2)d.sub.1 +d.sub.2 +d.sub.3 +d.sub.4 +d.sub.5 <0.45 Fs (3)0.6<r.sub.4 /r.sub.5 <1.0, (4)where:Fs is the minimum focal length of the overall zoom lens,n.sub.i is the refractive index of the i-th lens at d-line,.nu..sub.i is the Abbe number of the i-th lens,r.sub.

Abstract: A compact wide angle zoom lens in order from the object side, of a divergent front lens group and a convergent rear lens group, the overall focal length being variable by mechanical movement of the front and rear lens groups. The divergent front lens group is composed, in order from the object side, of a first lens being a negative meniscus lens convex toward the object side, a second lens being a double convex positive lens or a positive cemented lens having positive and negative lenses, a third lens being a negative meniscus lens convex toward the object side, a fourth lens being a negative lens and a fifth lens being a positive lens. The convergent rear lens group is composed of a sixth lens being a positive lens, a seventh lens being a positive meniscus lens convex toward the object, an eighth lens being a double convex positive lens, a ninth lens being a double concave negative lens, the eighth and ninth lenses being cemented to each other, and the tenth lens being a positive lens.

Abstract: The present invention relates to a wide angle zoom lens system having a high variation ratio and a zooming range between a wide angle and a semi-telescopic angle, with the zoom ratio being approximately 2.3 to 3.0 times. The present invention provides the wide variation especially at the wide angle portion of the zoom. The present invention comprises, in order from the object side, a first lens group I having a positive focal length f.sub.I, a second lens group II (also referred to as a first variator lens group) having a negative focal length f.sub.II, and a third lens group III (also referred to as a second variator lens group) having a positive focal length f.sub.III. The present invention may include a lens group III' having a positive focal length f.sub.III'. The lens group III' may be disposed along the optical axis either at the image side or at the object side of the third lens group III. The lens group III' is unmovable during zooming.

Abstract: Compact, high performance low zoom ratio variable viewing angle lens systems are provided by constructing the lens systems of two lens groups separated by a variable aerial space and limiting the dimensions of the lens systems by various mathematical conditions.