Abstract: An apparatus has a zoom lens and an image pickup element disposed on the image side of the zoom lens that converts an optical image formed by the zoom lens into an electrical signal. The zoom lens includes, in order from the object side to the image side, a negative first lens unit, a negative second lens unit, a positive third lens unit, and a negative fourth lens unit. During zooming from the wide angle end to the telephoto end, the distance between the first lens unit and the second lens unit changes, the distance between the second lens unit and the third lens unit changes, and the distance between the third lens unit and the fourth lens unit changes, the distance between the second lens unit and the third lens unit being smaller at the telephoto end than at the wide angle end. The first lens unit includes a reflecting surface that deflects the optical path, and the zoom lens satisfies the following condition (1): ?100<fg4/ihw<?2.5 (1).

Abstract: A zoom lens including, in an order from an object side to an image side, a first lens group having a positive refracting power, a second lens group having a negative refracting power, and a rear group including at least one lens group, the zooming operation being performed by changing a spacing of the lens groups, wherein the zoom lens has an aperture stop and, when the second lens group is taken as a first focus group and a sub-lens group constituting a portion of one lens group of the rear group is taken as a second focus group, the lens structure and the movement amount of the first and second focus groups are set appropriately.

Abstract: Provided are a variable magnification optical system for making it possible to properly set a variable magnification ratio of each lens group by properly setting a variable magnification ratio of a fifth lens group, and an optical apparatus with the variable magnification optical system, and a method for manufacturing the variable magnification optical system. The optical apparatus has first to sixth lens groups (G1) to (G6) in order from an object, wherein the fifth lens group (G5) satisfies the following conditional expression: 0.65<|?5T/?5W|<3.20, where ?5T denotes the lateral magnification at the telephoto end state, and ?5W denotes the lateral magnification at the wide-angle end state.

Abstract: A high performance zoom lens system suitable for use with a camera is disclosed. The zoom lens systems employs liquid optics and a movable lens group to provide optical performance over the zoom focal length range at focus distances from close to infinity. The system also provides compensation for undesirable thermally induced effects by adjustments of the zoom group and the variably shaped optical surface in the liquid lens cell.

Abstract: A projection zoom lens includes in order from an enlargement side: a first lens group with negative power; a second lens group with positive power; a third lens group with positive power; a fourth lens group with positive power; and a fifth lens group with positive power, wherein the first and fifth lens groups are fixed and the second, third, and fourth lens groups move when zooming from a wide angle side to a telescopic side, the second lens group includes only a positive lens which is convex toward the enlargement side, and assuming that the focal length at a wide angle end of a whole system including the first to fifth lens groups is F and the focal length of the second lens group is F2, the following conditional expression (1) is satisfied: 0.05<F/F2<0.23??(1).

Abstract: A lens system having, in order from an object, at least a first lens group G1 having positive refractive power, and second to fourth lens groups G2 to G4, wherein the first lens group G1 includes a front portion lens group G1a, and a rear portion lens group G1b which is disposed to an image side of the front portion lens group G1a with an air distance therebetween, and performs focusing by shifting the rear portion lens group G1b in the optical axis direction, and the fourth lens group G4 includes, in order from the object, a negative lens and a positive lens (cemented negative lens L41), a negative lens L42, and an aperture stop S, and is fixed in the optical axis direction with respect to an image plane I upon zooming from a wide angle end state to a telephoto end state.

Abstract: A variable magnification optical system of the present invention and an image pickup device and a digital apparatus including this are provided with a four-component optical system of negative-negative-positive-negative arrangement, wherein a first lens group thereof includes only one negative lens as a lens having an optical power, and a third lens group thereof satisfies a conditional expression of 1.4<?3t/?3w<4 when ?3t and ?3w respectively denote image magnifications of the third lens group at a telephoto end and at a wide-angle end. The variable magnification optical system, the image pickup device and the digital apparatus having such a construction can be further downsized.

Abstract: A zoom lens having an optical element for deflecting an optical path includes, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having negative refractive power. The third lens group has a plurality of lenses, and the following conditional expressions 1.00<PL/fW<1.75 and 0.30<PL/fT<0.45 are satisfied, where PL denotes an optical path length of the optical element for deflecting the optical path, fW denotes a focal length of the zoom lens in a wide angle end state, and fT denotes a focal length of the zoom lens in a telephoto end state.

Abstract: A zoom lens includes 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 negative refractive power, and a fifth lens unit having a positive refractive power. The first to fifth lens units are arranged in order from the object side to the image side. All of the lens units are moved during zooming from the wide-angle end to the telephoto end such that the distance between the first lens unit and the second lens unit is increased and the distance between the third lens unit and the fifth lens unit is increased. The refractive power of the fourth lens unit and the refractive power of the fifth lens unit are adequately set with respect to the zoom ratio.

Abstract: The invention relates to a zoom lens and an imaging apparatus incorporating the same, and more particularly to a zoom lens of small format that lends itself to imaging apparatus inclusive of video cameras and digital cameras. The zoom lens comprises, in order from its object side, a first lens group G1 of positive refracting power, a second lens group G2 of negative refracting power and a third lens group G3 of positive refracting power. Zooming is implemented by changing the space between the respective lens groups. The first lens group G1 comprises one negative lens and one positive lens in order from the object side. The zoom lens satisfies conditions (1) and (2): 5.0<ft/fw<50.0??(1) 1.4<Nd1p<1.7??(2) where fw is the focal length of the whole zoom lens system at a wide-angle end, ft is the focal length of the whole zoom lens system at a telephoto end, and Nd1p is the d-line refractive index of the positive lens in the first lens group.

Abstract: A zoom lens includes, in order from an enlargement conjugate side to a reduction conjugate side, a first lens unit of negative refractive power; a second lens unit of positive refractive power; a third lens unit of positive refractive power, the third lens unit having at least three lens elements; a middle lens unit including at least one lens unit; and a last lens unit of positive refractive power. All the lens units, except the first lens unit and the last lens unit, move during zooming. The zoom lens satisfies appropriate conditions.

Abstract: A zoom lens is provided and includes: in order from an object side thereof, a first group having a positive refractive power; a second group having a negative refractive power; a stop; a third group having a negative refractive power, the third group including at least two positive lenses and at least two negative lenses; and a fourth group having a positive refractive power. Power variation from a wide angle end to a telephoto end of the zoom lens is performed by moving the second group to an image side along an optical axis thereof, while the first group and the third group are fixed, and correction of an image plane caused by the power variation and focusing is performed by moving the fourth group along the optical axis.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power, a fourth lens group having positive refractive power, a fifth lens group having positive refractive power, and a sixth lens group having positive refractive power. The zoom lens satisfies the following conditions: (1) 25<TT/fw<27; (2) 8.5 mm<BFL<12.5 mm; and (3) (V2+V5)?(V1+V6)>60. TT is a distance from the object side of the first lens group to the image side of the sixth lens group, fw is a shortest focal length of the zoom lens, BFL is a distance from the image side of the sixth lens group to the imaging sensor, and V1, V2, V5, V6 are Abbe numbers of the first, second, fifth, and sixth lens group, respectively.

Abstract: A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit.

Abstract: Providing a zoom lens system being compact and simple having excellent optical performance suitable for an optical apparatus with a limited space for a zoom lens, and capable of shifting an image, and an optical apparatus equipped therewith. The system includes, in order from an object: a first group having positive power and an optical path bending element; a second group having negative power; a third group having positive power; and a fourth group having positive power. Upon zooming from a wide-angle end to a telephoto end, the first and third groups are fixed relative to an image plane, the second group and the fourth group are moved along the optical axis, an image on the image plane can be shifted by shifting the third group or a portion thereof substantially perpendicularly to the optical axis. The first group includes at least one negative lens, and satisfies a given condition.

Abstract: A zoom lens includes, sequentially from an object side, a first lens group that is negative; and a second lens group that is positive, where focal length is varied by varying a distance between the first lens group and the second lens group. The first lens group includes, from the object side, a first lens that is a negative biconcave lens having at least one aspherical surface, and a second lens that is a positive meniscus lens having a convex surface facing toward the object side and at least one aspherical surface, and a first condition 0.8<|f1/f2|<1.0 and a second condition 0.5<|r2/f1|<0.8 are satisfied, where f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, r2 is radius of curvature of a surface of the first lens in the first lens group, the surface facing toward an image.

Abstract: A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system according to the present invention, in order from an object side to an image side, comprises: a first lens unit having positive optical power; a second lens unit having negative optical power; and at least two subsequent lens units, wherein the at least two subsequent lens units include a lens unit A and a lens unit B arranged on the image side relative to the lens unit A, at the time of zooming, all lens units move in a direction along the optical axis so that intervals between the lens units vary, at the time of focusing, the lens unit A moves in a direction along the optical axis, and the following condition is satisfied. 0.10<|fBAK/fF|/(fT/fW)<15.

Abstract: A zoom lens system includes, in order from an object side to an image side, first to fifth lens group respectively having positive, negative, positive, positive, and positive refractive power. When zooming from a wide-angle end to a telephoto end, the first, third and fourth lens groups move to the object side and the second lens group moves to the image side, whereby a spacing between the first and second lens groups and a spacing between the fourth and fifth lens groups are both increased and a spacing between the second and third lens groups is decreased. The following condition is satisfied: 0 < ? M ? ? G ? ? 2 · Y f ? ? 2 ? ? 0.05 where MG2 represents the movement range of the second lens group when zooming from the wide-angle end to the telephoto end, Y represents a maximum diagonal length of the image plane, and f2 represents the focal length of the second lens group.

Abstract: A zoom lens system comprising a plurality of lens units each composed of at least one lens element, wherein an interval between at least any two lens units is changed so that an optical image is formed with a continuously variable magnification, the zoom lens system comprises a first lens unit having positive power, a second lens unit that includes a lens element having a reflecting surface and has negative power and subsequent lens units including at least one lens unit having positive power, and the condition: 0.50<(C?S)/H<1.00(C=?(2R·dR?dR2), S is a sag of the image side surface of the most object side lens element in the second lens unit at height H, H is one-half of an optical axial thickness of the lens element having a reflecting surface, R is a radius of curvature of the image side surface, and dR is an interval between the most object side lens element and the lens element having a reflecting surface) is satisfied.

Abstract: A compact zoom lens system includes, in order from an object side to an image side along an optical axis thereof, a first lens group having positive refractive power, a second lens group having positive refractive power and a third lens group also having positive refractive power. The first lens group is stationary and includes a reflecting element for bending the optical path. The second and third lens groups are movable along the optical axis, and each of the first, second and third lens groups has at least one aspheric lens surface. When zooming from a wide-angle end to a telephoto end, the second lens group moves toward the object side and the third lens group moves toward the image side, so as to reduce the spacing between the first and second lens groups and increase the spacing between the second and third lens groups. By this specific optical configuration, the compact zoom lens system has the advantages of small size, simple structure, low cost, good reliability and better image quality.

Abstract: A zoom lens ZL installed in an electronic still camera 1 includes a first lens group G1 having positive refractive power disposed to the most object side, a second lens group G2 disposed to an image side of the first lens group G1, and a Gn lens group having positive refractive power disposed to the most image side. Upon zooming, the first lens group G1 and the Gn lens group are fixed. Upon focusing, at least one lens group disposed between the second lens group G2 and the Gn lens group are moved as a focusing lens group Gf. With this lens configuration, it becomes possible to provide a zoom lens having an optical property capable of coping with a vibration reduction, and an optical apparatus equipped therewith, and a method for manufacturing the zoom lens.

Abstract: A zoom lens including, in order from an object side to an image side, a first group having a negative focal length, a second group having a positive focal length, a third group having a negative focal length, a fourth group having a positive focal length, and an aperture stop between the second group and the third group, wherein when changing a magnification from a short focus end to a long focus end, at least the second group monotonically moves from the image side to the object side such that a distance between the first group and the second group decreases, and a distance between the second group and the third group increases, and the third group includes a three-cemented lens having a negative lens, a positive lens and a negative lens in order from the object side.

Abstract: A zoom lens includes, in order from an object side to an image side, a positive refractive, fixed first lens unit; a negative refractive second lens unit movable mainly for zooming; a positive refractive, fixed third lens unit; a positive refractive fourth lens unit movable for focal-position correction and focusing performed in response to zooming; and a positive refractive fifth lens unit. The fifth lens unit includes, in order from the object side to the image side, a negative refractive, fixed sub-unit; and a positive refractive sub-unit movable substantially perpendicularly to an optical axis. An image formed on an image surface is movable substantially perpendicularly to the optical axis by moving the movable sub-unit substantially perpendicularly to the optical axis. An aperture stop is provided on the object side of the third lens unit. The third lens unit includes a positive refractive sub-unit and a negative refractive sub-unit.

Abstract: A zoom lens includes first to fifth lens groups respectively having positive, negative, positive, positive, and negative refractive powers in that order from the object side. Zooming is performed by moving the second lens group and the fourth lens group in an optical-axis direction. The first lens group includes a front lens group having a negative refractive power, an optical member for bending an optical path, and a rear lens group having a positive refractive power in that order from the object side. The front lens group is a cemented lens in which a first lens having a negative refractive power is bonded to a second lens having a positive refractive power in that order from the object side to the image side.

Abstract: Provided is a zoom lens system including a compact focusing lens unit and having a suppressed change in image magnification at the time of movement of the focusing lens unit. The zoom lens system of the present invention includes, in order from an object side to an image side, a first lens unit G1 having negative optical power, a second lens unit G2 having positive optical power, a third lens unit G3 having positive optical power, and a fourth lens unit G4 having negative optical power. The fourth lens unit G4 moves to the image side along an optical axis at the time of focusing from an infinity in-focus condition to a close-point in-focus condition.

Abstract: A zoom lens includes: a first lens group with a positive refractive power, including a reflection optical element; a second lens group with a negative refractive power; a third lens group with a positive refractive power; a fourth lens group with a positive refractive power; and a fifth lens group with a negative refractive power. A power of the zoom lens varies by moving the second lens group, the fourth lens group, and the fifth lens group along an optical axis. A negative lens in the first lens group or a positive lens in the second lens group satisfies the predetermined conditions relating to a refractive index and an Abbe number.

Abstract: A zoom lens system including, in order from object-side to image-side: a positive first lens unit, a second negative lens unit, a third lens unit and a fourth positive lens units, in which: the fourth unit includes a front subunit having positive power and a rear subunit having positive power; the following conditions are satisfied: ?2.100×10?3×?d+0.693<?gF, 0.555<?gF<0.900, where ?d and ?gF indicate Abbe number and partial dispersion ratio of a lens included in the rear subunit, respectively; 0.8<(?fp/?fn)/(?rp/?rn)<4.0, 0.

Abstract: A zoom lens comprises the following lens groups in the order from an object side a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a positive refracting power; and a fifth lens group having a positive refracting power; wherein, upon zooming from a wide-angle end state to a telephoto end state, at least the first lens group and the fourth lens group move to the object side to vary a space between the first lens group and the second lens group, vary a space between the second lens group and the third lens group, vary a space between the third lens group and the fourth lens group, and vary a space between the fourth lens group and the fifth lens group; and wherein the fifth lens group comprises a front lens group, and a rear lens group arranged with an air space on an image side of the front lens group, and the fifth lens group is configured to move the front lens group i

Abstract: A zoom lens includes a first lens unit having a negative optical power located closest to an enlargement side. In the zoom lens, a focal length of the zoom lens at a wide-angle end (fw) and a focal length of the first lens unit (f1) satisfy the following condition: ?2.50<f1/fw<?1.36.

Abstract: A zoom lens system includes 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 positive refracting power, and a fourth lens unit having a negative refracting power. At the time of zooming from a wide angle end to a telephoto end, the second lens unit moves such that a distance between the first lens unit and the second lens unit decreases, and distances between the other lens units change. The first lens unit includes in order from the object side, one negative lens component having an aspheric surface at least on one surface, and one positive lens component, the fourth lens unit includes one negative lens component having a surface on the object side as a concave surface, and satisfies the following conditional expression (1) ?4<(R4a+R4b)/(R4a?R4b)<?0.

Abstract: A zoom lens includes: a front group including a plurality of movable lens groups; and a rear group that is provided on an image side of the front group and that includes a negative lens and a positive lens. The positive lens has a flat lens surface on its image side, and is tiltable about a spherical center of its object side lens surface that is convex on the object side. When a lens system is inclined, the positive lens is tilted in relation to the optical axis of the lens system based on: a focal length of the overall lens system; an angle of the optical axis of the lens system after being inclined in relation to the optical axis before being inclined; a distance between the image side lens surface of the positive lens and the image plane; and a refractive index of the positive lens.

Abstract: A zoom lens system comprising a first lens unit having negative power, a second lens unit having positive power and a third lens unit having positive power, wherein: the first lens unit comprises a first lens element having a concave surface at least on the image side and negative power and a second lens element having a convex surface at least on the object side and positive power; the second lens unit comprises a cemented lens element fabricated by two lens elements having optical power of mutually different signs and one single lens element; in zooming, all of the lens units move along an optical axis; and conditions (1): 5.0<?iW<20.0 and (I-2): n11?1.9 (where, 3.

Abstract: A zoom lens comprises, in order from an object side, a first lens group with a negative refracting power; a second lens group with a positive refracting power; a third lens group with a positive refracting power; and a fourth lens group with a refracting curved surface. Upon zooming from a wide-angle end to telephoto end, at least the first lens group, second lens group, and third lens group move, and a spacing between the respective lens groups are changed. The first lens group comprises; in order from the object side to an image side, a negative lens component with a negative refracting power and a positive lens component with a positive refracting power which are arranged on an optical axis with a predetermined spacing therebetween. The total number of the lens components in the first lens group is two.

Abstract: A zoom lens includes first to fourth lens units in order from the object side to the image side. The first, third, and fourth lens units have a positive refractive power. The second lens unit has a negative refractive power. Distances between the lens units are changed during zooming. The first lens unit is composed of a cemented lens including a first lens having a negative refractive power and a second lens having a positive refractive power arranged in order from the object side to the image side. The Nd1a and ?d1a are a refractive index and an Abbe number, respectively, of a material of the first lens for the d-line and are adequately set.

Abstract: A zoom lens and imaging apparatus implementing four lens groups including a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a positive refractive power. When a positional state is varied from a wide-angle-end state to a telephoto-end state, the second lens group is moved to an image side, and the fourth lens group is moved to compensate for image plane variation caused by the movement of the second lens group.

Abstract: A zoom lens consists of, in order from its object side, a first lens group of negative refracting power, and a second lens group of positive refractive power. Zooming from a wide-angle end to a telephoto end is implemented by changing a distance between the respective lens groups. The first lens group consists of, in order from its object side, a front unit of negative refracting power, and a rear unit of negative refracting power. The front unit consists of, in order from its object side, a first lens that has negative refracting power, and a second lens with smaller refracting power than the first lens. The rear unit consists of, in order from its object side, a third lens of negative refracting power, a fourth lens of negative refracting power, and a fifth lens that has positive refracting power.

Abstract: The invention relates to a high-performance imaging optical system that achieves a magnification high enough to be capable of microscopic viewing under an endoscope, and is compatible with high-definition imaging devices. The objective optical system comprises, at least in order from the object side, a positive, first group G1, a second group G2 and a third group G3. In association with an object point change, at least the second group G2 is moved along an optical axis. The objective optical system satisfies a condition with respect to an optical magnification ? upon focusing on the closest range.

Abstract: A zoom lens is provided and includes: a first lens group having a positive power, a second lens group having a negative power, a stop, a third lens group having a positive power, and a fourth lens group having a positive power in order. Zooming is performed by moving at least the first lens group, the second lens group, the stop, and the third lens group along the optical axis. During zooming, the stop is moved so as to be closer to an image plane at a wide-angle end than at a telephoto end and to be closer to the second lens group at the telephoto end than at the wide-angle end. The following conditional expressions (1) and (2) are satisfied. For the conditional expressions (1) and (2), fw is a focal length at the wide-angle end of the entire system, ft is a focal length at the telephoto end of the entire system, f1 is a composite focal length of the first lens group, and X1 is a displacement of the first lens group during zooming from the wide-angle end to the telephoto end. 4.0<f1/fw<7.0??(1) 0.

Abstract: A zoom lens system includes, in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, and a third lens unit having a positive refractive power. During zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit narrows, at least the second lens unit moves only toward the object side, and the third lens unit is constituted of one positive lens.

Abstract: A zoom lens includes, in order from the object side thereof, a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, a third lens unit having a positive refracting power, a fourth lens unit having a positive refracting power, and a fifth lens unit having a negative refracting power. During zooming from the wide angle end to the telephoto end, the first lens unit and the third lens unit are kept stationary with respect to the image plane, and at least the second lens unit and the fourth lens unit move. The first lens unit includes, in order from the object side, a first sub unit having a negative refracting power, a reflecting optical element that bends an optical path by reflection, and a second sub unit having a positive refracting power. The second sub unit includes a cemented lens.

Abstract: The present zoom lens system comprises a plurality of lens units including at least: a front lens unit having negative optical power; and a rear lens unit having positive optical power, arranged on the image side of the front lens unit, and composed of a plurality of lens elements; wherein magnification change is performed by changing an interval between the individual lens units, wherein the rear lens unit comprises: a rear A lens unit capable of moving in a direction perpendicular to an optical axis; and a rear B lens unit that is arranged on the image side of the rear A lens unit and that can move in an optical axis direction in such a manner that an interval relative to the rear A lens unit in the optical axis direction is changed, and wherein focusing adjustment during variation of the object distance is achieved by changing the interval between the rear A lens unit and the rear B lens unit.

Abstract: A zoom lens system includes, in order from an object side to an image side, first to fifth lens groups respectively having negative, positive, negative, positive, and positive refractive power. During zooming from a wide-angle end to a telephoto end, the second and third lens groups are moved independently toward the object side with spacing therebetween increased and that between the first and second lens groups decreased. The following condition is satisfied 1.05?(fW·LW)/(fT·Y)?1.53, wherein fW and fT are focal lengths of the zoom lens system at the wide-angle end and the telephoto end, Y represents a maximum diagonal length of an image plane, and LW represents a total length of the zoom lens system at the wide-angle end which is defined as a distance from the vertex of a first surface of the first lens on the object side to the image plane.

Abstract: A first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having the negative refractive power, and a fourth lens group having the positive refractive power are included in order from an object side, and variation of magnification from a wide-angle end to a telephoto end is performed by monotonically moving the second lens group toward an image side and compensation of a fluctuation of an image surface resulting from the variation of magnification is performed by moving the third lens group. At least one positive lens having an optical material satisfying a conditional expressions is included in at least one of the first lens group G1 and the fourth lens group.

Abstract: The projection zoom lens system includes a negative first lens group, a positive second lens group, a third lens group, a positive fourth lens group, a fifth lens group, and a positive sixth lens group. The lens system is nearly telecentric on a reduction side. During zooming, the second to fifth lens groups are moved while the first and six lens groups remain stationary. The third lens group includes a positive lens LP having a convex surface directed to a magnification side, and a negative lens LN having a concave surface which is directed to the reduction side and has a curvature stronger than a magnification-side surface of the negative lens LN. The conditional expression of 5.0?|fG3/RLN-2| is satisfied. Here, fG3 denotes a focal length of the third lens group, and RLN-2 denotes a radius of curvature of the reduction-side surface of the negative lens LN.

Abstract: A zoom lens system includes, in order from an object side to an image side, first, second, third, and fourth lens units having positive, negative, positive, and positive optical powers, respectively. The first lens unit includes one negative lens element and two positive lens elements, and moves during zooming. The zoom lens system satisfies the following condition: 0.05<f1/(st1×ft/fw)<0.2 1.5<?3T/?3W<3.6 where f1 denotes a focal length of the first lens unit, st1 denotes a distance between positions of the first lens unit at a wide-angle end and at a telephoto end, fw and ft denote focal lengths of the entire system at the wide-angle end and at the telephoto end, respectively, and ?3W and ?3T denote lateral magnifications of the third lens unit at the wide-angle end and at the telephoto end, respectively.

Abstract: A projection lens system includes, in order from the magnification side, a negative first group G1 and positive second to fifth groups G2 to G5. In the lens system, the first group G1 has aspheric surface, a lens closest to the magnification side (L7) in the fourth group G4 has an aspheric surface, and the fifth group G5 is formed of one positive lens. During zooming, the first group G1 and the fifth group G5 remain stationary, while the second to fourth groups G2 to G4 are moved separately. Furthermore, the lens system satisfies the expression 0.8<d34/fw, where fw denotes a focal length of the whole system at the wide-angle end, and d34 denotes an air space between the third lens group G3 and the fourth lens group G4 at the wide-angle end.

Abstract: A zoom lens having an optical element for deflecting an optical path includes, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having negative refractive power. The third lens group has a plurality of lenses, and the following conditional expressions 1.00<PL/fW<1.75 and 0.30<PL/fT<0.45 are satisfied, where PL denotes an optical path length of the optical element for deflecting the optical path, fW denotes a focal length of the zoom lens in a wide angle end state, and fT denotes a focal length of the zoom lens in a telephoto end state.

Abstract: A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system according to the present invention, in order from an object side to an image side, comprises: a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having positive optical power; and an aperture diaphragm. At the time of zooming, the zoom lens system moves the first to third lens units so that intervals between these lens units vary. At the time of focusing from an infinity in-focus condition to a close-point object in-focus condition, the zoom lens system moves the third lens unit to the object side.

Abstract: A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system according to the present invention comprises: a positive lens unit that is arranged on an object side relative to the aperture diaphragm; a negative lens unit that is arranged on an image side relative to the positive lens unit and on an object side relative to the aperture diaphragm; and a focusing lens unit that is arranged in an optical path between the negative lens unit and the aperture diaphragm. The zoom lens system satisfies the condition (4): 1.20<?NT/?NW<4.50 (here, fT/fW>3.

Abstract: A zoom lens system is provided that includes a compactly constructed focusing lens unit and that has a suppressed change in the image magnification at the time of movement of a focusing lens unit. The zoom lens system according to the present invention comprises a plurality of lens units and an aperture diaphragm arranged in the lens unit. The plurality of lens units include: a negative lens unit that is arranged on an object side relative to the aperture diaphragm and provided with negative optical power having an absolute value greatest in the entire system and that moves in a direction along an optical axis at the time of zooming; and a focusing lens unit that is arranged in an optical path between the negative lens unit and the aperture diaphragm and that moves in a direction along the optical axis at the time of focusing such that an interval relative to the negative lens unit should vary.