Abstract: A zoom lens system has a first set of lenses having a positive focal length and a second set of lenses having a negative focal length. The first set of lenses which is located closer to the object than the second set constitutes a reflecting system, while the second set of lenses constitutes a transmission lens system.

Abstract: A compact telephoto zoom lens is composed of twelve lenses grouped into nine lens groups. These include, from the object side, a variator system including a first lens group functioning as a focusing group having a positive focal length, a second lens group functioning as a main variator having a negative focal length, a third lens group functioning as a compensator for maintaining an image plane constant which has a positive focal length, and a relay lens system. The first lens group includes a positive meniscus lens convex on the object side and a positive cemented lens composed of a negative meniscus lens convex on the object side and a positive lens. The second lens group includes a negative lens whose lens concave surfaces confront one another and a negative cemented lens composed of a biconcave and a positive lens. The third lens group includes a positive cemented lens composed of a biconvex lens and a negative meniscus lens while the relay lens system includes first and second fourth lens groups.

Abstract: A variable power copying lens system having an intermediate range of variable magnification with superior distortion aberration compensation and compact size. The lens system includes, in order from the object side, a first lens group having a negative focal length, a second lens group having a positive focal length and a third lens group having a negative focal length. The distance between the first and second lens groups and the distance between the second and third lens groups is variable simultaneously with variation of the overall lens system position to thereby maintain the distance between the object surface and image surface constant.

Abstract: A zoom lens for a copying system capable of both magnification and reduction of the image of an original to be copied in which the overall lens system may be miniaturized but yet various aberrations such as distortion are well corrected for. The lens includes a first lens group having a negative focal length and a second lens group having a positive focal length disposed in that order from the object side of the lens system. The distance between the first and second lens groups is variable while the distance between the object surface and the image surface is maintained constant. Movement of the first lens group serves primarily to maintain constant the distance between the object and image surfaces while the movement of the second lens group serves mainly to provide a variator effect.

Abstract: The present invention provides a compact zoom lens which exhibits small distortion aberration. The lens system comprises, in order from the object side, a front lens group having a negative focal length and a rear lens group having a positive focal length. The front lens group is a first lens group. The rear lens group is separated into a second lens group having a positive focal length and a third lens group having a negative focal length. The overall focal length is variable by moving mechanically the first, second and third lens groups, but the position of the image surface is maintained constant. The first lens group comprises, in order from the object side, positive, negative and positive units. The second lens group comprises, in order from the object side, positive, negative and positive units. The third lens group comprises, in order from the object side, a positive lens, a double concave negative lens and a positive lens.

Abstract: A miniaturized, super-wide angle zoom lens system of the two lens group type wherein barrel shaped distortion aberration in the wide angle position is compensated for by providing one of the lenses with an aspherical surface.

Abstract: The present invention provides a compact zoom lens which exhibits only small distortion aberration. The present invention comprises, in order from the object side, a first lens group having a negative focal length, a second lens group having a positive focal length, and a third lens group having a negative focal length. The overall focal length is variable by moving mechanically the first, second and third lens groups, but the position of the image surface is maintained constant. In the zoom lens of the present invention, the resultant focal length of the first and second lens groups is positive during the entire zoom range, and the aerial spaces between the first and second lens groups and between the second and third lens groups, respectively, are reduced so that the overall viewing angle is also reduced. The first lens group is composed of a negative lens component and a positive lens component in order from the object side. The negative lens component is constructed using two negative lenses.

Abstract: A two lens group type of miniaturized zoom lens system having a minimum wide end viewing angle of 76.degree. and a zoom ratio at least 2.3. The first or object side lens group includes at least two positive and two negative lenses with the image side lens being positive. The second or image side lens group includes at least two positive lenses facing the object. The variable aperture is mounted in front of the second lens group and the fixed aperture, which may be proportionally movable, is mounted behind the second lens group. The overall lens system satisfies the following conditions: ##EQU1## wherein: Z is the zoom ratio (Z=f.sub.T /f.sub.W),f.sub.1 is the focal length of the first lens groups,f.sub.2 is the focal length of the second lens group,f.sub.W is the focal length in the wide angle position,f.sub.T is the focal length in the telescopic or narrow angle position, andr.sub.

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.

Abstract: A zoom lens having small distortion including a front lens group having a negative focal length and a rear lens group having a positive focal length, the front and rear lens groups being mechanically movable to vary the overall focal length while maintaining the image position constant.