Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: The invention relates to a new mechanism for permitting a zoom lens to focus on a short distance subject by moving a focusing lens group in an amount that varies in an optical axis direction depending on a zooming position. The zoom lens comprises, in order from its object side, a positive first lens group, a negative second lens group and a positive third lens group. Zooming is implemented while the space between adjoining lens groups is varied, and focusing on a short distance subject is implemented by moving the negative second lens group in an amount that varies in the optical axis direction depending on a zooming position. The negative second lens group comprises a negative front unit G2F and a negative rear unit G2R. The space between the negative front unit G2F and the negative rear unit G2R is varied depending on a subject distance but that space remains constant wherever the zooming position lies.

Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: The invention relates to a zoom lens in which tweaks to the mode of movement of lens groups and the first lens group contribute more to making sure the desired zoom ratio and optical performances and ensuring that the whole length of the zoom lens is kept short while carrying it around. The zoom lens comprises a positive first lens group G1, a negative second lens group G2 and a positive third lens group G3, and includes an aperture stop S located between the second G2 and the third lens group G3. Upon zooming from the wide-angle end to the telephoto end, the first lens group G1 moves in unison, and the second lens group G2 moves in unison. The first G1 and the second lens group G2 are positioned nearer to the object side at the telephoto end than at the wide-angle end, with an increasing spacing between the first G1 and the second lens group G2 and a decreasing spacing between the second G2 and the third lens group G3.

Abstract: A zoom lens comprises, in order from an object side to an image side, a lens group having negative refracting power, and a lens group having positive refracting power. Zooming is carried out with a change in a space between at least said two lens groups. The lens group having negative refracting power comprises a plurality of aspheric surfaces. The lens group having positive refracting power comprises at least one aspherie surface. The lens group having negative refracting power comprises at least three negative lenses, with satisfaction of the following condition: 2.3<|f2/f1<3.1, where f1 is a focal length of said lens group having negative refracting power, and f2 is a focal length of said lens group having positive refracting power.

Abstract: The invention relates to a wide-angle zoom lens adapted for use with a single-lens reflex camera incorporating an image pickup device for which an increased back focus is needed. The zoom lens comprises, in order from its object side, a lens group FG having negative refracting power and a lens group RG having positive refracting power, wherein zooming is carried out with a change in the space between at least two lens groups.

Abstract: A zoom lens according to the present invention includes, in 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 negative refractive power, and a fourth lens unit having a positive refractive power. During a magnification change from the wide-angle end through the telephoto end, the first lens unit and the fourth lens unit shift from the image-surface side toward the object side, a space between the first lens unit and the second lens unit increases, and spaces between individual lens units change. During a focusing from an object at the infinite distance onto an object at a near distance, the second lens unit and the third lens unit individually shift independently.

Abstract: A zoom lens according to the present invention includes, in 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 negative refractive power, and a fourth lens unit having a positive refractive power. During a magnification change from the wide-angle end through the telephoto end, the first lens unit and the fourth lens unit shift from the image-surface side toward the object side, a space between the first lens unit and the second lens unit increases, and spaces between individual lens units change. During a focusing from an object at the infinite distance onto an object at a near distance, the second lens unit and the third lens unit individually shift independently.

Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: A compact yet low-cost zoom lens system being particularly suited for use with small portable information terminal equipment is provided. The zoom lens system includes, in order from an object side thereof, a first, third and fourth lens groups G1, G3 and G4 that have positive refracting powers and a second lens group G2 that has negative refracting power. Lens group G1 remains fixed during zooming and lens groups G2 and G3 move during zooming and lens group G4 is movable during zooming. In one embodiment, the zoom lens system includes a negative lens located nearest to the imaging side of the second lens group G2 that satisfies condition (7).

Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: The invention provides a compact yet low-cost zoom lens system which is particularly suited for use with small portable information terminal equipment. The zoom lens system comprises, in order from an object side thereof, a first lens group G1 that has positive refracting power and remains fixed during zooming, a second lens group G2 that has negative refracting power and moves from the object side to an image plane side of the system during zooming from a wide-angle end to a telephoto end of the system, a third lens group G3 that has positive refracting power and moves from the image plane side to the object side during zooming from the wide-angle end to the telephoto end and a fourth lens group G4 that has positive refracting power and is movable during zooming.

Abstract: A compact yet low-cost zoom lens system being particularly suited for use with small portable information terminal equipment is provided. The zoom lens system includes, in order from an object side thereof, first, third and fourth lens groups G1, G3 and G4, respectively, that have positive refracting powers and a second lens group G2 that has negative refracting power. Lens group G1 remains fixed during zooming and lens groups G2 and G3 move during zooming and lens group G4 is movable during zooming. the zoom lens system should satisfy condition (1) regarding the power of lens group G3, condition (2) regarding the amount of movement of lens group G3 during zooming condition (3) regarding the composite power of lens groups G3 and G4, and condition (10) regarding the actual value of the back focus.

Abstract: A camera having an autofocus function, independent of a photographing optical system, includes a photographing optical system including synthetic resin lenses and an autofocus optical system, provided independent of the photographing optical system, having at least one synthetic resin lens and a stop decentered in a direction perpendicular to the optical axis of the synthetic resin lens. Thus, in the camera, the shift of the imaging position of the photographing optical system which is caused by an ambient temperature or humidity change is favorably corrected, and good photography can be performed.

Abstract: The invention provides a zoom lens system that is reduced in terms of both size and cost. The zoom lens system comprises a first positive lens group G1, a second negative lens group G2, a stop S, a third positive lens group G3 and a fourth positive lens group G4. During zooming from a wide-angle end to a telephoto end of the system, while the first lens group G1 remains fixed, the second lens group G2 moves from an object side to an image plane side of the system, the third lens group G3 moves from the image plane side to the object side, and the fourth lens group G4 moves to keep an image plane at a constant position.

Abstract: A zoom lens system for use on compact cameras, which has a high zoom ratio, is provided at a minimum cost. The zoom lens system comprises a first positive lens group G1, a second positive lens group G2 and a third negative lens group G3 with a focal length of the system varied with changes in spacings between the lens groups. The first lens group G1 comprises one positive lens and one negative lens, and the third lens group G3 consists of one negative plastic lens. The zoom lens system satisfies1<(r.sub.2F +r.sub.2R)/(r.sub.2F -r.sub.2R)<6where r.sub.2F is a radius of curvature of a surface of the negative lens in the first lens group that faces the object side of the system and r.sub.2R is a radium of curvature of a surface of the negative lens in the first lens group that faces the image side of the system.

Abstract: A camera having an autofocus function, independent of a photographing optical system, includes a photographing optical system including synthetic resin lenses and an autofocus optical system, provided independent of the photographing optical system, having at least one synthetic resin lens and a stop decentered in a direction perpendicular to the optical axis of the synthetic resin lens. Thus, in the camera, the shift of the imaging position of the photographing optical system which is caused by an ambient temperature or humidity change is favorably corrected, and good photography can be performed.

Abstract: The invention provides a compact, lightweight yet low-cost zoom lens system which has a zoom ratio of at least about 2 and is well corrected for various aberrations, and in which sufficient attention is paid to temperature compensation when plastic lenses are used. The zoom lens system comprises in order from an object side a front lens group GF including a plurality of positive lenses containing at least a plastic lens and having a positive refracting power as a whole, and a rear lens group GR composed only of a plurality of negative lenses containing at least a plastic lens, wherein zooming is carried out by varying the spacing between the front and rear lens groups, and all the lenses satisfy the following condition (1):n.sub.d <1.75 (1)where n.sub.d is the d-line indices of refraction of the lenses.

Abstract: The invention provides a zoom lens system having a zoom ratio as high as about 8 to 12 but is of wide field angle and small size, and is suitable for use on a video camera, said zoom lens system comprising a positive first lens unit L1 which is movable in an orbit, said orbit displaceable toward objet side at the telephoto end position rather than at the wide-angle end position, a negative second lens unit L2 which is movable in an orbit, said orbit displaceable toward the image side at the telephoto end position rather than at the wide-angle end position, a positive third lens unit L3 which is movable in an orbit, said orbit displaceable toward the object side at the telephoto end position rather than at the wide-angle end, and a positive or negative fourth lens unit L4 which is movable, and conforming to2.6<f.sub.l /(f.sub.W .multidot.f.sub.T).sup.1/2 <6 (1)-1.2<.beta..sub.2T <-0.7 (2)3.2<.beta..sub.2T /.beta..sub.2W <8 (3)where:f.sub.l is the focal length of the first lens unit,f.sub.

Abstract: A zoom lens system comprising, in order from the object side, a first lens unit which has a positive refractive power and is kept fixed during zooming, a second lens unit which has a negative refractive power, is movable for zooming and has a vari-focal function, a third lens unit which has a positive refractive power and is movable for zooming, and a fourth lens unit which has a positive refractive power and is movable for zooming; a location of the third lens unit at a tele position of the zoom lens system being on the object side of a location of the third lens unit at a wide position of the zoom lens system. This zoom lens system consists of a small number of lens components, and has a vari-focal ratio of 9 to 12 and a wide field angle of 65.degree. to 68.degree. at the wide position thereof.