Abstract: A variable magnification zoom lens system comprising: in order from the object side, a first lens group having a negative refractive power and a focal length f1; a second lens group having a positive refractive power; and a third lens group having a positive refractive power and a focal length f3 with the first and second lens group arranged to be driven together such that when zooming is performed from the maximum wide-angle state to the maximum telephoto state of the zoom lens system, the first lens group and the second lens group move such that the distance between the first lens group and the second lens group is decreased, and at the same time, the distance between second lens group and the third lens group is increased and with the following condition being fulfilled: 0.4<f3/.vertline.f1.vertline.<0.8.

Abstract: A super-wide angle lens, sequentially from an object side, comprises a first negative lens L1, a second negative lens L2, and a third positive lens L3. The first negative lens L1 with its concave surface toward an image side has an image-side surface with a curvature larger than that on an object-side surface. The second negative lens L2 is disposed at a predetermined spacing from the first negative lens L1 and takes a negative meniscus shape with its convex surface toward the object side. The third positive lens L3 has its convex surface toward the object side.

Abstract: A viewfinder having a high magnification ratio permits satisfactory correction of aberration in spite of its compact and simple structure. An objective lens group of the viewfinder includes a first lens unit having negative refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power and varies magnification by moving at least the second lens unit. Moreover, the first lens unit includes at least one negative lens, the second lens unit includes at least two positive lenses, and the third lens unit includes at least one negative lens. Furthermore, the positive lens is formed so that an object-side surface is aspherical and a predetermined condition is satisfied.

Abstract: A high-performance eyepiece is provided having a high-power magnification finder and a large pupil diameter even if it is used for a camera finder using a pentagonal mirror. The eyepiece includes, in order from the eyepoint end, a negative meniscus lens and a bifocal convex lens, which fulfills the following conditions:0.88<d1/d3<2.7and0.15<r1/f1<0.26where:d1 is the center thickness of the negative meniscus lens;d3 is the center thickness of the biconvex lens;r1 is the radius of curvature of the surface at the eyepoint end of the negative meniscus lens; andf1 is the focal length of the negative meniscus lens.

Abstract: A position controlling device in a lens system with a variable focal length with high-precision focusing having a small amount of required recorded information, even when there are large number of divisions of the object distance and of the focal length includes a distance measuring device that detects the object position and transmits photographic distance information. A detecting device detects the movement amount from a standard position of the movable lens group of the lens system when the focal length of the lens system changes. A calculating device calculates the required movement of the focusing lens unit of the lens system, based on the photographic distance information and the movement amount of the movable lens unit. Finally, a controlling device drives the focusing lens unit and performs focusing, based on the required movement calculated by the calculating device. The movable lens unit moves monotonically to the object side or to an image side when the focal length of the lens system is changed.

Abstract: In a camera comprising a phototaking lens system and a viewfinder lens system having a different optical axis from that of the phototaking lens system, the camera comprises a drive means, for simultaneously zooming the phototaking lens system and the viewfinder lens system, which simultaneously shifts at least one of the lens groups of the phototaking lens system and at least one of the lens groups of the viewfinder lens system. The drive means simultaneously focuses the phototaking lens system and the viewfinder lens system on an object by simultaneously shifting at least one of the lens groups of the phototaking lens system and at least one of the lens groups of the viewfinder lens system based on the position data of the object.

Abstract: A large diameter zoom lens includes a large zooming ratio which is capable of faster auto focussing (AF). A zoom lens, having a zooming ratio of not less than 1.5, includes, in order from an object side to an image side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power and a fifth lens group having positive refractive power, wherein during zooming from a maximum wide-angle state to a maximum telephoto state, the lateral magnification of the second lens group is always positive and decreases monotonically, and predetermined conditional equations are satisfied.

Abstract: A large diameter zoom lens includes a large zooming ratio which is capable of faster auto focussing (AF). A zoom lens, having a zooming ratio of not less than 1.5, includes, in order from an object side to an image side, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, a fourth lens group having negative refractive power and a fifth lens group having positive refractive power, wherein during zooming from a maximum wide-angle state to a maximum telephoto state, the lateral magnification of the second lens group is always positive and decreases monotonically, and predetermined conditional equations are satisfied.

Abstract: A telephoto lens includes, in the following order from the object side, a positive cemented lens component composed of a biconvex lens and a biconcave lens and having a meniscus shape as a whole with the convex side facing the object side, and a negative meniscus lens component with the convex side facing the image side.

Abstract: A camera having an apparatus for correcting parallax includes viewfinder optical system for viewing an object. A shooting lens system for photographing the object is disposed such that the optical axis of the shooting lens system is different from the optical axis of the viewfinder optical system. The shooting lens system includes a correcting lens group such that image shift is accomplished by decentering the correcting lens group. A focusing lens group, spaced from the correcting lens group, is moveable along the optical axis of the shooting lens system. Parallax that is created by changes in the position of the object is corrected by accomplishing an image shift by the shooting lens system.

Abstract: A Keplerian zoom finder optical system comprises an objective lens group having a positive refracting power on the whole and constructed of, in order from an object side, a first lens unit having a negative refracting power, a second lens unit having a positive refracting power, a third lens unit having a negative refracting power and a fourth lens unit having a positive refracting power. This finder also comprises a regulating element, disposed in the vicinity of a focal position of the objective lens group, for regulating a visual field. The finder further comprises an eyepiece unit having a positive refracting power. The finder varies a magnification by moving at least the second lens unit along an optical axis and satisfies the following condition:-5<f.sub.3 /f.sub.w <-3wheref.sub.w : the synthetic focal length of the first and second lens units in a minimum magnification state, andf.sub.3 : the focal length of the third lens unit.

Abstract: A lens system has a front unit having a positive refractive power and a rear unit having a negative refractive power, in order from the object side, and performs a refractive power varying (zooming) operation by changing an air gap between the two units. The front unit is composed of three lens components of negative, negative, and positive refractive powers.

Abstract: A Keplerian zoom finder optical system has an objective lens comprising, in succession from the object side, a first lens unit of negative refractive power, a second lens unit of positive refractive power, and a third lens unit of positive refractive power and having positive refractive power as a whole, and an eyepiece of positive refractive power for enlarging and observing the focused image of the objective lens therethrough. The air gap between the first lens unit and the second lens unit is varied to thereby vary finder magnification.

Abstract: The lens system includes, in order from an object side, a 1-st lens unit having a positive refractive power which has at least two positive lens elements and a negative lens element positioned on an image side of said positive lens elements, a 2-nd lens unit having a positive refractive power and a 3-rd lens unit having a positive refractive power. During focusing, both 1-st and 3-rd lens units are fixed, whereas the 2-nd lens unit is movable along an optical axis. The lens system satisfies at least one of the conditions 1.8<F1/f<2.4 and 0.8<F2/f<0.96.

Abstract: In a phototaking lens with the focal length variable from a predetermined value at the wide-angle end position to another predetermined value at the telephoto end position, a part of lens elements constituting the phototaking lens is rendered movable relative to other lens components. There is provided means for converting the lens, by the relative movement of a part of the lens elements, to a panorama state with a focal length even shorter than that at the wide-angle end position. The phototaking lens is a zoom lens having a first lens group of a positive refractive power and a second lens group of a negative refractive power in the order from the object side, wherein the focal length is varied by a change in the distance between the first and second lens groups, and the panorama state is obtained by a relative movement of the first lens group relative to the second lens group.

Abstract: In a large-aperture medium-range telephoto lens system, which includes, in the following order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a positive refractive power, and attains focusing by moving the second and third lens units along the optical axis while the first lens unit is fixed in position, the telephoto lens system satisfies:______________________________________ 0.8 < f1/f < 1.5 -3.0 < f2/f < -1.0 0.7 < f3/f < 1.0 0.02 < .vertline.x2/x3.vertline. < 0.

Abstract: A lens holding device and a lens system equipped with the holding device are simple in structure and low in cost. The lens holding device includes a cylindrical lens barrel that is structured as one body with a single plastic lens and has an inside diameter larger than the effective diameter of the plastic lens. A holding ring, made from an impermeable substance, holds at least one lens that has been inserted into the lens barrel and fixes the position of the lens. The holding ring covers the edge surface of the lens barrel.

Abstract: A triplet lens using plastic lens elements is disclosed. The triplet lens includes, in order from the object side, a glass lens element that is positively meniscus having the convex surface on the object side, a plastic lens element formed of polycarbonate, polystyrene, or a copolymer of polystyrene and methacrylate which is biconcave in shape with a more pronounced concave surface on the image side, a plastic lens having a copolymer of polystyrene and methacrylate that is biconvex in shape, and a diaphragm. Lens characteristics are chosen to satisfy various conditions for optimum imaging.

Abstract: A camera comprises a photographing lens, a finder having its optical axis disposed substantially in parallel with the optical axis of the photographing lens and a lens drive for moving the photographing lens for focusing, the lens drive including a guide member for rectilinearly moving the photographing lens in a direction set at a predetermined angle to the optical axis of the photographing lens.

Abstract: A large aperture wide angle type photographic lens system comprises a positive meniscus lens having a convex surface directed toward an object, a bi-concave lens provided at the image side with respect to the positive meniscus lens, a bi-convex lens provided at the image side with respect to the bi-concave lens and a negative meniscus lens having a convex surface directed toward an image and provided at the image side with respect to the bi-convex lens. The characteristics of the lenses have predetermined relationship.