Abstract: A high performance zoom lens with a high zoom ratio is suitable for a wide range of uses. The zoom lens includes, in order from the object side, 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 the fifth lens group having a positive refractive power. A magnification of the second lens group, a magnification of the third lens group and a magnification of the fourth lens group almost simultaneously attain near equal magnification. The zoom lens system satisfies at least one predetermined condition.

Abstract: Disclosed is a zoom lens of an internal focusing system, comprising: a positive focusing lens group positioned close to an object and incorporating a focusing function; and a zoom variable power optical system including a negative variable power lens group disposed towards an image of the focusing lens group and having such a variable power function as to be movable along an optical axis. The focusing lens group includes, sequentially from an object, a first lens element having a positive refractive power, a second lens element having a positive refractive power and movable along an optical axis and a third lens element having a negative refractive power. Only the second lens element is moved along the optical axis to change a synthetic focal distance of the focusing lens group, thus effecting focusing.

Abstract: A lens for an underwater camera is comprised of a first lens unit having no refractive power or having weak refractive power, a second lens unit comprising a forward unit having negative refractive power and a rearward unit having positive refractive power, and having weak refractive power, a third lens unit having positive refractive power, and a fourth lens unit having negative refractive power, the first lens unit being fixed relative to the image plane, the second lens unit and the third lens unit being axially moved together on the optical axis toward the object side relative to the fourth lens unit.

Abstract: The rear conversion lens of the present invention is compact and maintains an excellent imaging performance even when it is mounted on a telephoto objective lens the enlargement magnification of whose focal length is relatively high, e.g. about double and whose F-number is of the order of 2-2.8, and moreover does not intercept a light beam even in the fully open state of the aperture. The rear conversion lens of the present invention is an RCL adapted to be mounted on the image side of an objective lens and having negative refractive power for enlarging the combined focal length of itself and the objective lens, and has, in succession from the objective lens side, a first lens unit of positive or negative refractive power, a second lens unit of negative refractive power and a third lens unit of positive refractive power, the first lens unit having a positive lens most adjacent to the object side, and when the air gap between the first lens unit and the second lens unit is D.sub.

Abstract: A camera system and a rear conversion lens both of which accurately calculate the distance .DELTA.X a focusing lens moves when the rear conversion lens is interposed between an interchangeable lens and the camera body, even when the distance .DELTA.Bf an image surface of the focusing lens shifts, increases, so that a subject can be focused quickly.A factor K.sub.0 for converting the distance the image surface of an interchangeable lens shifts and a factor C.sub.0 for correcting the conversion factor K.sub.0 are stored, and the magnification .beta.c and the focal length fc of the rear conversion lens are also stored independently of the above two factors. The distance .DELTA.X is calculated with precision. The subject can thus be automatically focused smoothly and quickly.

Abstract: A system camera provided with a rear conversion lens barrel interposed between an interchangeable photo-taking lens barrel and a camera body comprises a camera body having a focus detecting apparatus for detecting the amount of deviation of the image plane and a first converting device for correcting the amount of deviation of the image plane detected by the focus detecting apparatus, an interchangeable photo-taking lens barrel disposed forwardly of the camera body and having an interchangeable photo-taking lens and a first memory for storing therein data regarding the exit pupil position PO from the focal plane of the interchangeable photo-taking lens, a rear conversion lens barrel interposed between the interchangeable phototaking lens barrel and the camera body and having a rear conversion lens and a second memory for storing therein data regarding the magnification .beta..sub.R and focal length f.sub.

Abstract: An inner focusing type telephoto zoom lens includes a fixed first lens group having a positive refractive power, the first lens group being disposed closest to the object, a second lens group having a negative refractive power, the second lens group being movable along an optical axis for focusing, a fixed third lens group having a positive refractive power, a fourth lens group having a negative refractive power, the fourth lens group being movable along the optical axis for zooming, a fifth lens group having a positive refractive power, the fifth lens group being movable along the optical axis relative to the fourth lens group, and a fixed sixth lens group having a positive refractive power. The zoom lens satisfies the following condition:0.4<.vertline.f.sub.2 .vertline./f.sub.123 <0.9where f.sub.123 is a composite focal length of the first, second and third lens groups, and f.sub.2 indicates a focal length of the second lens group.

Abstract: A telephoto zoom lens, when viewed from the object, comprises: a first lens group having positive refracting power; a second lens group having negative refracting power; a third lens group having positive refacting power; a fourth lens group having positive refracting power; and a fifth lens group having negative refacting power, wherein, when magnification is varied from the wide angle end to the telephoto end, an air interval between the first lens group and the second lens group is enlarged, an air interval between the second lens group and the third lens group is reduced, an air interval between the third lens group and the fourth lens group is enlarged and an air interval between the fourth lens group and the fifth lens group is reduced.

Abstract: A lens system enabling close distance photographing has an excellent image forming performance for a wide focussing range from infinite distance to equi-magnification distance while employing a relatively simple lens composition. The lens system has a basic composition including a 1st group of positive refractive power, a 2nd group of positive refractive power and a 3rd group of negative refractive power arranged in this order from the object side and in focussing from infinite distance to closest distance, the 1st group and the 2nd group move to the object side away from the 3rd group, which is fixed relative to the image plane, while expanding the space between the 1st and the 2nd groups, the 3rd negative group has a positive lens and a negative lens arranged in this order from the object side.

Abstract: An automatic focusing device for use in camera lens systems comprises lens means such as a zoom lens for forming the image of an object, detecting means for detecting the amount of defocus of the image of the object formed by the lens means from a predetermined plane such as a film surface, memory means for storing at least one value of conversion coefficient and at least one value of correction coefficient which is used in a calculation for correcting the conversion coefficient, calculating means for correcting the conversion coefficient in accordance with the amount of defocus and the correction coefficient and for calculating the driving amount of at least a portion of the lens means on the basis of the corrected conversion coefficient and the amount of defocus, and lens driving means for driving at least a portion of the lens means, e.g., the front lens group of a zoom lens, in accordance with the driving amount calculated by the calculating means.

Abstract: A detecting apparatus for focus in a camera has a memory storing at least two independent rates indicating an aberration of a photographing lens. The memory is provided on an interchangeable photographing lens. If an optical characteristic of the focus detecting apparatus within the camera body changes from a conventional one, a suitable aberration correction rate is decided accordingly on a camera body side, thereby ensuring a high precision focus detection then forward.

Abstract: An auto focusing light device detachably mounted on a camera has a plurality of photoelectric conversion elements arranged in a unidimensional direction and detects the focusing condition of a photographic lens in accordance with the output of the plurality of photoelectric conversion elements. The device comprises a plurality of light-emitting elements arranged in a unidimensional direction, and an optical projection system for projecting images of the plurality of light-emitting elements on an object in such a manner that the direction of arrangement of the images of the plurality of light-emitting elements is substantially perpendicular to the direction of arrangement of the plurality of photoelectric conversion elements.

Abstract: A photo-taking lens assembly having a movable lens movable in the direction of the optic axis thereof comprises electric moving means including an electric rotating member electrically rotatively driven to move the movable lens, manual moving means including a manually operable member extraneously manually operable to move the movable lens, and means for combining the amounts of movement of the movable lens by the electric moving means and the manual moving means during the operation of the electric rotating member and the manually operable member.

Abstract: A rear conversion lens apparatus mounted between an objective lens and a camera body for enlarging the focal length of the composite system of the rear conversion lens apparatus and the objective lens more than the focal length of the objective lens includes a converter barrel removably mounted between the objective lens and the camera body, a lens group of negative refractive power movable along the optic axis within the converter barrel, the lens group of negative refractive power having a forward subgroup and a rearward subgroup, the forward subgroup having a negative meniscus lens disposed most adjacent to the object side and having its convex surface facing the object side and a positive lens disposed on the image side of the negative meniscus lens, and moving means for moving the lens group of negative refractive power along the optic axis. Focusing to objects at infinity to a short distance is effected by the movement of the negative lens group by the moving means.

Abstract: A rear conversion lens is composed of a front lens group comprising three lenses of positive, negative and positive from the object side and a rear lens group comprising two lenses of negative and positive from the object side and satisfying certain conditions.

Abstract: A rear-focus conversion lens device is interposed between an objective lens and a camera body so as to provide a focal length of a combined lens system with the objective lens greater than that of the objective lens. The conversion lens device has a movable lens system which is movable on an optical axis relative to the objective lens and the camera body. The conversion lens device can focus on an object falling within a range of infinity and a predetermined short distance by moving the movable lens system. The conversion lens device satisfies certain conditions.

Abstract: A four-group telephoto zoom lens consists of, in succession from the object side, first group having a positive refracting power and movable on the optical axis of the lens for focusing, second group having a negative refracting power and movable on the optical axis for changing a composite focal distance of an entire system, a third group having a positive refracting power and movable on the optical axis for maintaining image plane at a fixed position and a fourth group as relay lens system having a positive refracting power. The second group consists of a first cemented negative lens component having, in the order from the object side, a positive lens and a negative lens cemented together and a second cemented negative lens component having a negative lens and a positive lens cemented together. The four-group telephoto zoom lens further satisfies a certain condition.

Abstract: A photographic lens of a great aperture ratio comprises, in succession from the object side, a first unit having a positive refractive power, a second unit having a positive refractive power, a third unit having a positive refractive power, and a stop member disposed between the first unit and the second unit. The first, second and third units are movable at different speeds toward the object side relative to the image plane during the shift from the infinity photography condition to the short distance photography condition. The photographic lens satisfies certain conditions.

Abstract: A rear conversion lens removably mounted between an objective lens and a camera body for making the combined focal length of the rear conversion lens and the objective lens greater than the focal length of the objective lens includes a converter barrel, a lens group of negative refractive power movable in the converter barrel along the optical axis, and means for moving the lens group of negative refractive power along the optical axis. Focusing to objects from infinity to a short distance is effected by the movement of the lens group of negative refractive power by said moving means.

Abstract: A rear conversion lens for a single lens reflex camera, constructed with a front lens group including a positive lens with its surface having a greater curvature facing to the image side, a negative biconcave lens, and a positive lens with its surface having a greater curvature facing to the object side, and a rear lens group including a negative lens, the rear conversion lens being provided between an objective lens and a camera body to extend a composite focal length, and satisfying certain conditions.