Abstract: A zoom lens system comprising a front lens unit having a negative refractive power and a rear lens unit having a positive refractive power, and configured so as to perform a change of a magnification thereof by varying an airspace reserved between these two lens units. The rear lens unit consists, in order from the object side, of a positive lens component, a positive lens component and a negative lens component which has at least one aspherical surface. The zoom lens system is composed of a small number of lens elements, sufficiently compact, and has high optical performance, a wide field angle and a high vari-focal ratio.

Abstract: The invention provides a four-unit type of zoom lens system which is of compact size albeit having a high zoom ratio, and comprises a first unit G1 of positive refracting power, a second unit G2 of positive refracting power, a third unit G3 of negative refracting power, and a fourth unit G4 of negative refracting power, wherein the spaces between the units vary during zooming, said zoom lens system being characterized in that all these units are moved toward the object side for zooming from the wide-angle to telephoto end.

Abstract: A wide-angle photographic lens system comprising a front lens unit having a positive refractive power, an aperture stop and a rear lens unit having a positive refractive power or a negative refractive power; the front lens unit comprising at least one positive lens component and at least one negative lens component, whereas said rear lens unit consisting of a positive lens component having a convex surface on the image side. This photographic lens system has a short total length (a length as measured from a first surface to an image side surface of the lens system and a small value of .SIGMA.d (a distance as measured from the first surface to a final surface thereof), and is suited for use with collapsible mount type cameras.

Abstract: The invention provides a two-unit or positive-negative type of zoom lens that has a zoom range of the order of 38-70 mm, comprises six lens groups or six lenses, and makes use of an aspherical plastic lens for cost reduction and for improving its performance as well. This zoom lens system is constructed from a first unit I of positive power and a second unit II of negative power and is designed to be variable in the air space between both the units for zooming. The first unit I includes a positive meniscus lens L1 convex on the object side, a negative lens L2, a positive lens L3 and a lens L4, and the second unit II includes a positive meniscus lens L5 convex on the image side and a negative meniscus lens L6 convex on the image side. At least L5 consists of a plastic lens having an aspherical surface.

Abstract: The present invention provides a three-unit zoom lens system comprising, in order from the object side, a first lens unit G1 consisting of a negative meniscus lens convex on the object side and a positive meniscus lens convex on the object side and having a positive refracting power as a whole, a second lens unit G2 consisting of one positive lens, or one negative lens and one positive lens, and having a positive refracting power as a whole and a third lens unit G3 consisting of one negative lens, said first and second lens units being movable toward each other for zooming from the wide to tele position. This compact zoom lens system comprises 4 or 5 lenses and is of sufficient performance in terms of a zoom ratio of 1.5 to 2.

Abstract: The present invention provides a two-unit zoom lens system comprising, in order from the object side, a first lens unit G1 having a negative refracting power and a second lens unit G2 consisting of a first positive sub-lens-unit P1 , a first negative sub-lens-unit N1, a second positive sub-lens-unit P2 and a second negative sub-lens-unit N2 and having a positive refracting power as a whole, and including an air gap between said first and second lens units, which is variable for zooming. In this zoom lens system which is made waterproof, inexpensive and of high performance, the amount of movement of the first lens unit G1 in association with zooming is reduced.

Abstract: A zoom lens system comprising, in the order from the object side, a first lens unit having positive refractive power, a second lens unit having positive refractive power and a third lens unit having negative refractive power, and so adapted as to vary focal length from the wide position to the tele position by displacing the first lens unit integrally with the third lens unit toward the object side and displacing the second lens unit toward the object side at a speed slower than that of the first lens unit, said zoom lens system having such a composition as to permit simplifying structure of the driving mechanism for varying focal length, a compact design and favorable performance.

Abstract: A telephoto zoom lens system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a stop fixedly arranged in respect to the third lens group, wherein the first lens group comprises a positive lens and a negative lens, the telephoto zoom lens sytem being arranged to be zoomed by moving the first lens group, the third lens group and the stop in the same direction and further arranged that the variation in the position of the entrance pupil to be caused at the time of zooming is small, it is possible to ensure satisfactory intensity of light in the marginal portion, and aberrations are corrected favorably.

Abstract: A telephoto zoom lens system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group comprising a front subgroup, which has positive refractive power, and a rear subgroup, the telephoto zoom lens system being arranged that the focal length thereof is varied by moving the first, second and third lens groups along the optical axis in the state that the varifocal functions is alloted to the second and third lens groups so that the magnifications of both of them increase at that time, the telephoto zoom lens system being thereby arranged to be small in size, high-performanced and low cost.

Abstract: A zoom lens system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having positive refractive power wherein the fourth lens group comprises a positive, positive and negative lens components, the zoom lens system having a large zoom ratio and large aperture ratio, i.e., F/5.0, and being compact in size and low in price.

Abstract: A large-aperture macro lens system comprising a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power in the order from the object side and arranged that, when focusing on an object at the shortest object distance from the state that the lens system is focused on an object at the infinite distance, the airspace between the first and second lens groups is varied in a pattern that the above-mentioned airspace is increased and, then, decreased by changing the varying direction near the position of the intermediate photographing magnification while the airspace between the second and third lens groups is increased continuously, the large-apertured macro lens system being arranged that aberrations are corrected favourably over the whole range of object distance from the infinite distance up to the distance corresponding to the photographing magnification of 1x, variation of aberrations, especially, variation

Abstract: A zoom lens system comprising a first lens group having positive refractive power and having a focusing function, a second lens group having negative refractive power and having a vari-focal function, a third lens group having positive refractive power and having a vari-focal function, and a fourth lens group having positive refractive power and having a vari-focal function, wherein the second lens group comprises a negative lens having a surface with strong curvature on the image side, a cemented doublet consisting of a negative lens and a positive lens, a negative lens having a surface with strong curvature on the object side, and a positive meniscus lens having a surface with strong curvature on the object side, the zoom lens system having a large vari-focal ratio and a large aperture ratio and arranged compactly.