Abstract: A zoom lens including, in order from object side: a positive first unit fixed for zooming; a negative second unit moving for zooming; a zoom unit including at least one unit moving for zooming; a stop; and a fixed unit. The first unit includes a negative first sub-unit not moving for focusing, and a positive second sub-unit and a positive third sub-unit moving toward image side and object side, respectively, when focusing from infinity object to proximity object. A focal lengths of the first and second units, a distance from a vertex of a surface closest to the image side in the first unit to an image side principal point position of the first unit, a thickness of the first unit on an optical axis, and lateral magnifications of the second and third sub-units when focusing on infinity object are appropriately set.

Abstract: A zoom lens includes, in order from an object side: a first lens unit having positive refractive power which does not move for varying magnification; a magnification-varying lens unit including at least two lens units which move for varying magnification; an aperture stop; and an imaging lens unit having positive refractive power which does not move for varying magnification, in which: the first lens unit includes, in order from the object side, a first sub-lens unit having positive refractive power, a second sub-lens unit having negative refractive power, and a third sub-lens unit having positive refractive power; the second sub-lens unit is driven to the object side so as to perform focus adjustment to an object at a short distance; and the following expression is satisfied: 0.07<f1/f11<0.35, where f1 represents a focal length of the first lens unit, and f11 represents a focal length of the first sub-lens unit.

Abstract: A zoom lens includes, in order from object side: a positive first lens unit which does not move for zooming; a zoom lens unit including at least two lens units which move for zooming; a stop; and a positive imaging lens unit which does not move for zooming, in which: the first lens unit includes, in order from object side, a positive first sub-lens unit, a negative second sub-lens unit, and a positive third sub-lens unit; the third sub-lens unit includes a movable positive sub-third sub-lens unit; the second sub-lens unit and sub-third sub-lens unit are driven to object side for focusing to a close object; and focal length f12 of the second sub-lens unit, focal length f13f of the sub-third sub-lens unit, drive amount ?×12 of the second sub-lens unit in focusing, and drive amount ?×13f of the sub-third sub-lens unit in focusing satisfy ?2.5<f12/f13f<?0.4 and 0.05<?×13f/?×12<5.0.

Abstract: A zoom lens including, in order from object side: a positive first unit fixed for zooming; a negative second unit moving for zooming; a zoom unit including at least one unit moving for zooming; a stop; and a fixed unit. The first unit includes a negative first sub-unit not moving for focusing, and a positive second sub-unit and a positive third sub-unit moving toward image side and object side, respectively, when focusing from infinity object to proximity object. A focal lengths of the first and second units, a distance from a vertex of a surface closest to the image side in the first unit to an image side principal point position of the first unit, a thickness of the first unit on an optical axis, and lateral magnifications of the second and third sub-units when focusing on infinity object are appropriately set.

Abstract: A zoom lens includes, in order from an object side: a first lens unit having positive refractive power which does not move for varying magnification; a magnification-varying lens unit including at least two lens units which move for varying magnification; an aperture stop; and an imaging lens unit having positive refractive power which does not move for varying magnification, in which: the first lens unit includes, in order from the object side, a first sub-lens unit having positive refractive power, a second sub-lens unit having negative refractive power, and a third sub-lens unit having positive refractive power; the second sub-lens unit is driven to the object side so as to perform focus adjustment to an object at a short distance; and the following expression is satisfied: 0.07<f1/f11<0.35, where f1 represents a focal length of the first lens unit, and f11 represents a focal length of the first sub-lens unit.

Abstract: A zoom lens includes, in order from object side: a positive first lens unit which does not move for zooming; a zoom lens unit including at least two lens units which move for zooming; a stop; and a positive imaging lens unit which does not move for zooming, in which: the first lens unit includes, in order from object side, a positive first sub-lens unit, a negative second sub-lens unit, and a positive third sub-lens unit; the third sub-lens unit includes a movable positive sub-third sub-lens unit; the second sub-lens unit and sub-third sub-lens unit are driven to object side for focusing to a close object; and focal length f12 of the second sub-lens unit, focal length f13f of the sub-third sub-lens unit, drive amount ?×12 of the second sub-lens unit in focusing, and drive amount ?×13f of the sub-third sub-lens unit in focusing satisfy ?2.5<f12/f13f<?0.4 and 0.05<?×13f/?×12<5.0.

Abstract: An optical transmission device for providing stable communication with a partner device by reducing errors in optical axis misalignment. The errors are caused by uneven distribution of the light intensity in a received light beam resulting from atmospheric microscopic fluctuations. One embodiment includes a transmission and receiving unit, which employs two photodetectors, one aligned with and the other misaligned with the optical axis of the optical transmission device. Other embodiments employ a movable means for shifting a photodetector or a lens unit relative to the optical axis of the optical transmission device.

Abstract: A small-sized and light weight zoom lens achieving high optical performance, a wide angle of view, and a high magnification, is disclosed. The zoom lens comprises, in order form the object side, a first lens unit with positive optical power, a second lens unit with negative optical power having a magnification varying function, and at least one other lens unit. The first lens unit includes, in order from the object side, a first negative lens element the object side surface of which is concave toward the object side, a second negative lens element, and a positive lens element.

Abstract: An optical transmission device for providing stable communication with a partner device by reducing errors in optical axis misalignment. The errors are caused by uneven distribution of the light intensity in a received light beam resulting from atmospheric microscopic fluctuations. One embodiment includes a transmission and receiving unit, which employs two photodetectors, one aligned with and the other misaligned with the optical axis of the optical transmission device. Other embodiments employ a movable means for shifting a photodetector or a lens unit relative to the optical axis of the optical transmission device.

Abstract: A small-sized and light weight zoom lens achieving high optical performance, a wide angle of view, and a high magnification, is disclosed. The zoom lens comprises, in order form the object side, a first lens unit with positive optical power, a second lens unit with negative optical power having a magnification varying function, and at least one other lens unit. The first lens unit includes, in order from the object side, a first negative lens element the object side surface of which is concave toward the object side, a second negative lens element, and a positive lens element.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power arranged to move during variation of magnification, a third lens unit of negative refractive power arranged to compensate for shift of an image plane due to the variation of magnification, and a fourth lens unit of positive refractive power. The fourth lens unit has a focal-length changeover subunit arranged to be insertable onto and detachable from an optical axis of the zoom lens and provided for changing the focal length of the zoom lens, and an image-stabilizing lens subunit different from the focal-length changeover subunit. The image-stabilizing lens subunit is movable in such a way as to have a component perpendicular to the optical axis so as to displace an image.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power for variation of magnification, a third lens unit for compensating for shift of an image plane caused by the variation of magnification, and a fixed fourth lens unit of positive refractive power, wherein the first lens unit comprises a first lens subunit of negative refractive power fixed during focusing, a second lens subunit having a focusing function, and a third lens subunit of positive refractive power fixed during focusing, and at least one of the first lens subunit and the second lens subunit and the third lens subunit respectively have aspheric lenses.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power for variation of magnification, a third lens unit for compensating for shift of an image plane caused by the variation of magnification, and a fixed fourth lens unit of positive refractive power, wherein the first lens unit comprises a first lens subunit of negative refractive power fixed during focusing, a second lens subunit having a focusing function, and a third lens subunit of positive refractive power fixed during focusing, and at least one of the first lens subunit and the second lens subunit and the third lens subunit respectively have aspheric lenses.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power arranged to move during variation of magnification, a third lens unit of negative refractive power arranged to compensate for shift of an image plane due to the variation of magnification, and a fourth lens unit of positive refractive power. The fourth lens unit has a focal-length changeover subunit arranged to be insertable onto and detachable from an optical axis of the zoom lens and provided for changing the focal length of the zoom lens, and an image-stabilizing lens subunit different from the focal-length changeover subunit. The image-stabilizing lens subunit is movable in such a way as to have a component perpendicular to the optical axis so as to displace an image.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of positive refractive power, a second lens unit of negative refractive power arranged to move during variation of magnification, a third lens unit arranged to move during variation of magnification, and a fourth lens unit of positive refractive power. The first lens unit includes a first lens subunit arranged to be stationary during focusing, and a second lens subunit of positive refractive power arranged to move during focusing. The first lens subunit includes, in order from the object side to the image side, at least one first positive lens, at least one negative lens of bi-concave form, and at least one second positive lens.

Abstract: This specification discloses a zoom lens which has, in succession from the object side, a first lens unit of positive refractive power, a second lens unit of negative refractive power for focal length change, a third lens unit for correcting the changing of an imaging plane resulting from a focal length change, and a fourth lens unit of positive refractive power, and in which an aspherical surface AS1 is provided on at least one lens surface constituting the first lens unit and satisfying 1.65<hw/ht and 1.15<hw/hz, where ht is the maximum incidence height of an on-axis light beam, hw is the incidence height of an off-axis light beam of a maximum angle of view at the wide angle end, and hz is the incidence height of the off-axis light beam of a maximum angle of view at a zoom position at a variable power ratio Z.sup.1/4, and the power disposition and achromatism condition of the first lens unit, a focusing system, etc. are appropriately set.

Abstract: This specification discloses a zoom lens which has, in succession from the object side, a first lens unit of positive refractive power, a second lens unit having negative refractive power and movable during a focal length change, a third lens unit for correcting the changing of an image plane resulting from the movement of the second lens unit, and a fixed fourth lens unit having positive refractive power, and in which an aspherical surface of a predetermined shape for correcting well spherical aberration and distortion resulting from a focal length change is provided on a predetermined lens surface in the first lens unit.

Abstract: There is disclosed a zoom lens having, in order from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power and adapted to move in the zooming operation, a third lens unit for correcting the variation in the image plane resulting from the movement of the second lens unit, and a fixed fourth lens unit having a positive refractive power, wherein an aspherical surface of a predetermined shape for satisfactorily correcting the spherical aberration and the distortion aberration resulting from the zooming operation is applied onto a predetermined lens in the lens unit.

Abstract: A zoom lens is disclosed comprising, from front to rear a first lens unit of positive refractive power, a second lens unit of negative refractive power for varying the focal length, a third lens unit for compensating for the image shift with zooming, and a fourth lens unit having the image forming function and stationary during zooming, wherein the first lens unit is divided into two or three lens subunits, one of which is moved to effect focusing, and various rules of design are set forth to suppress well the variation of aberrations with focusing.

Abstract: A high range zoom lens is disclosed, comprising, from front to rear, a first lens unit of positive refractive power, a second lens unit of negative refractive power, a third lens unit of positive or negative refractive power and a fourth lens unit of positive refractive power, the second and third lens units being movable for zooming, wherein an aspheric surface is introduced into the second or third lens unit at a specified location so that the variation of aberrations with zooming is as far reduced for high performance as possible.