Abstract: The object of the invention is to reduce the size of a camera by the provision of a zoom lens system which has a high zoom ratio and a small telephoto ratio at the wide-angle and telephoto end, and is simple in lens arrangement and reduced in size during lens collapsing. The zoom lens system comprises a positive first lens group G1, a positive second lens group G2 and a negative third lens group G3. For zooming from a wide-angle end to a telephoto end of the system, each lens group moves toward the object side while a spacing between the first lens group and the second lens group becomes wide and a spacing between the second lens group and the third lens group becomes narrow. The first lens group G1 comprises at least one set of a negative lens and a positive lens. The second lens group G2 includes an aperture stop and comprises at least one set of a negative lens and a positive lens. The third lens group G3 comprises one set of a positive lens and a negative lens.

Abstract: The invention relates to a compact zoom lens system which can maintain sufficient image-formation capabilities at a wide-angle end of greater than 70° and at a zoom ratio of greater than about 10, and has a proper focusing mode. The zoom lens system comprises a first lens group G1 having positive refracting power, a second lens group G2 having negative refracting power, a third lens group G3 having positive refracting power, a fourth lens group G4 having negative refracting power and a fifth lens group G5 having positive refracting power. For zooming from a wide angle end to a telephoto end of the zoom lens system, the first lens group G1 to the fifth lens group G5 are all movable. During said zooming, the first lens group G1 and said third lens group G3 move toward the object side in such a way that the spacing between the first lens group G1 and the second lens group G2 becomes wide and the spacing between the third lens group G3 and the fourth lens group G4 becomes wide.

Abstract: The invention relates to a zoom lens system which, albeit having a high zoom ratio, is reduced in terms of length during lens collapsing and at the wide-angle end as well as the telephoto end, with well-corrected aberrations. The zoom lens system comprises a front lens group G1 located nearest to the object side and a rear lens group G3 located nearest to the image side with at least one lens group located between G1 and G3. The group G1 has positive or negative refracting power and the group G3 has negative refracting power. For zooming from the wide-angle end to the telephoto end, a separation between adjacent lens groups varies. Specific conditions are satisfied with respect to the focal length of G3, the amount of movement of G3, and the zoom ratio shared by G3.

Abstract: The invention provides a wide-angle yet high-magnification zoom lens system which can have satisfactory performance with a simple lens arrangement, and an optical system which can make satisfactory correction for off-axis aberrations becoming a problem in taking wide-angle shots. The zoom lens system comprises a first lens group G1 having negative power, a second lens group G2, a third lens group G3 having positive power, a fourth lens group G4 having negative power and a fifth lens group G5. For zooming, the first group G1 moves nonlinearly and the second group G2 to the fifth group G5 moves toward an object side of the system on a wide-angle end basis. For a wide-angle end to a telephoto end of the system, the lens groups move such that spacings between the first group G2 and the second group G2, between the second group G2 and the third group G3 and between the fourth group G4 and the fifth group G5 become narrow while a spacing between the third group G3 and the fourth group G4 becomes wide.

Abstract: The invention relates to a zoom lens system having stable performance and a high magnification, which comprises a first lens group G1 having positive refracting power, a second lens group G2 having negative refracting power, a third lens group G3 having positive refracting power and a fourth lens group G4 having negative refracting power. For zooming from a wide-angle end to a telephoto end of a zooming area having a continuous zooming action, an intergroup space of each lens group is varied. At least one group of the four lens groups is moved to define an extended wide-angle point SW that is a discontinuous zooming point at a position where a focal length thereof becomes shorter than the wide-angle end of the zooming area. At least one lens group of the four lens groups is moved to define an extended telephoto point ST that is a discontinuous zooming point at a position where a focal length thereof becomes longer than the telephoto end of the zooming area.

Abstract: A wide-angle lens system which has a long back focal length comprising a first lens unit having a negative power, a second lens unit having a positive power and a third lens unit having a positive power: the first lens unit being composed of a 1-1 positive lens unit which is composed only of a positive lens component and a 1-2 negative lens unit which is composed only of negative lens components, the third lens unit being composed of a 3-1 subunit which comprises at least a negative lens component and a 3-2 positive subunit which comprises at least a negative lens component, the 3-1 subunit being composed of a first negative lens component and a second positive lens component, and the 3-2 subunit being composed of a third negative lens component and a fourth positive lens component.

Abstract: A telephoto lens system consisting of a front lens group and a rear lens group: the front lens group being composed of a first lens unit which is composed only of a positive lens components and a second lens unit which is composed only of negative lens components, and the rear lens group being composed of a third positive lens unit, a fourth negative lens unit and a fifth positive lens unit. This lens system has a back focal length long enough to permit disposing filters such as a low pass filter and optical path splitting members.

Abstract: The present invention relates to a telephoto zoom lens system which is less variable in terms of aberrations incidental to zooming and focusing, and is of high image quality and large aperture ratio as well, and which consists essentially of a first lens group G1 having a positive refracting power, a second lens group G2 having a negative refracting power, a third lens group G3 having a negative refracting power, a fourth lens group G4 having a positive refracting power and a fifth lens group G5 having a positive refracting power. For zooming from the wide-angle zone to the telephoto zone, the second and third lens groups G2 and G3 are moved in conformity to specific conditional inequalities while the first and fifth lens groups G1 and G5 remain fixed, and fourth lens group G4 is moved separately from the movable lens groups G2 and G3 while acting primarily as means for compensating for an image surface position.

Abstract: A standard lens system composed, in order from the object side, of a first lens unit having a positive refractive power, an aperture stop, a second lens unit having a positive refractive power and a third lens unit having a negative refractive power: the first lens unit being composed of at least one positive meniscus lens component which has a convex surface on the object side, and at least one doublet which consists of a positive meniscus lens component and a negative lens component; the second lens unit being composed of at least one cemented doublet which consists of a negative lens element and a positive lens element, and a positive lens component; and the third lens unit being composed of at least one positive lens component and a negative lens component or at least one negative lens component.

Abstract: The invention provides an ultrawide-angle yet large aperture ratio lens system of the symmetrical type which, while taking aim at improving the vignetting factor and the performance of a sagittal image surface, achieves a field angle coverage of up to about 107.degree. and an aperture ratio of about 1:2.8 to 3.5, and which comprises a first group G1 of negative power, a second group G2 of positive power and a third group G3 of negative power. The first group G1 comprises at least one negative meniscus lens convex on an object side, the second group G2 comprises an aperture stop and one set of cemented lens, and the third group G3 comprises at least one negative meniscus lens convex on an image side, with an aspherical surface used in any one of the lens groups.

Abstract: The invention provides a solution to a problem of allowing a symmetrical wide-angle lens system to have a large aperture ratio, and achieves an optical system which is well improved in terms of sagittal coma and curvature of field, and has a satisfactory vignetting factor as well. The optical system comprises basically a first lens group G1 having a negative refracting power, a second lens group G2 containing an aperture stop and having a positive negative power, and a third lens group having a negative refracting power. The second lens group G2 is divided into front and rear sub-groups G.sub.21 and G.sub.22, each having a positive refracting power, between which the aperture stop is located. The first lens group G1 comprises at least one negative meniscus lens convex on an object side; the front sub-group G.sub.21 of the second lens group comprises at least one set of cemented lens including a positive lens and a negative lens; and the rear sub-group G.sub.

Abstract: The invention provides a telephoto lens system that enables the camera operator to shoot an infinite to nearby object with stably maintained optical quality. This lens system comprises a first positive lens unit G.sub.1, a second positive lens unit G.sub.2, a third negative lens unit G.sub.3 and a fourth positive lens unit G.sub.4. The first unit comprises at least two positive lenses and a negative meniscus lens heavily concave on the image surface side; the second unit comprises a positive lens heavily convex on the object side and a doublet consisting of negative and positive lenses; the third unit comprises a doublet consisting of negative and positive lenses; and the fourth unit comprises a cemented doublet consisting of negative and positive lenses. While the first and second units remain fixed, the third and fourth units are moved for focusing. Specific conditions regarding the focal lengths of the units, the separation between adjacent units, and the amount of movement of the units are satisfied.

Abstract: The invention provides a zooming lens system which covers a wide-angle zone, has a zooming ratio of approximately 3 or higher, and is well corrected for various aberrations. This system comprises, in order from the object side, a first lens unit I having positive refracting power, a second lens unit II having negative refracting power, a third lens unit III having positive refracting power, a fourth lens unit IV having positive refracting power and a fifth lens unit V having positive refracting power, with at least said first, third, fourth and fifth lens units being moved toward the object side for zooming from the wide-angle end to the telephoto end, and conforms to the following conditions:-0.8<f.sub.2 /f.sub.W <-0.5 (1)-0.7<f.sub.T12 /f.sub.T <-0.3 (2)Here f.sub.2 is the focal length of the second lens unit, f.sub.W is the focal length of the entire system at the wide-angle end, f.sub.T12 is the composite focal length of the first and second lens units at the telephoto end, and f.sub.

Abstract: A compact, wide-angle, fast zoom lens system of high optical performance which enables photography in the range of from the wide-angle region to the telephoto region. The zoom lens system has a 1-st lens unit (G1) of positive refractive power, a 2-nd lens unit (G2) of negative refractive power, a 3-rd lens unit (G3) of positive refractive power, a 4-th lens unit (G4) of positive refractive power, and a 5-th lens unit (G5) of positive refractive power. When zooming from the wide end toward the tele end is effected, the 1-st lens unit (G1), the 2-nd lens unit (G2), the 3-rd lens unit (G3) and the 4-th lens unit (G4) are movable, while the 5-th lens unit (G5) is fixed.

Abstract: A wide-angle lens system comprising, in order from the object side, a front unit, a stop and a rear unit: the front unit comprising, in order from the object side, a first lens unit which comprises a plurality of lens components including a positive lens component and has a negative refractive power as a whole, a negative lens component having a concave surface on the object side and a cemented lens component; and the rear unit comprising a negative lens component disposed on the side of the stop and at least two positive lens components. This wide-angle lens system has sufficiently corrected aberrations, in particular, negative distortion, curvature of field and sagittal coma.

Abstract: A zoom lens system comprising at least five lens units, in order from the object side, of a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a negative refractive power, a fourth lens unit having a positive refractive power and a fifth lens unit having a positive refractive power. This zoom lens system is configured so as to change a magnification thereof by moving the first through fifth lens units, and has wide field angles, a high vari-focal ratio and a compact size.

Abstract: A zoom lens system comprising a plurality of lens units, concretely in order from the object side, a first lens unit having negative refractive power, a second lens unit having positive refractive power, a third lens unit having negative refractive power and a fourth lens unit having positive or negative refractive power; wherein said zoom lens system is zoomed by moving the second lens unit, the third lens unit and the fourth lens unit so that locations of these lens units at a tele position are on the object side of locations thereof at a wide position, and said zoom lens system is focused by moving one of more lens components disposed in the first lens unit. This zoom lens system has a total length which is kept substantially constant regardless of zooming and focusing.

Abstract: A wide angle zoom lens system comprising, in order from the object side, a first positive lens unit, a second positive lens unit and a third negative lens unit; and configured so as to perform variation of focal length by varying airspaces reserved between these lens units. The first lens unit consists of a negative front subunit and a rear positive subunit. The zoom lens system has a wide field angle and favorable optical performance.

Abstract: A zoom lens system comprising, in the order from the object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit having a positive refractive power and a fifth lens unit having a negative refractive power, adapted so as to vary the focal length by moving said first through fourth lens units independently while keeping said fifth lens unit fixed, and adapted so as to perform focusing by moving at least one of said second through fifth lens units. This zoom lens system has a high vari-focal ratio, a wide field angle, a compact size, and optical performance stabilized regardless of zooming and focusing.

Abstract: A zoom lens system comprising a first lens unit having a positive refractive power, a second lens unit having a positive refractive power and a third lens unit having a negative refractive power, and is modifiable into a macro optical system for photographing an object located at an exceptionally short distance with favorable optical performance by varying the airspaces reserved among the lens units in a manner different from that for zooming.