Abstract: A zoom lens system according to the present invention, from an object 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 a fourth lens unit having positive optical power. In zooming, the first to the fourth units all move along the optical axis. The third lens unit is composed of three or more lens elements. The condition (6): nd8?1.5 and vd8?75 and the condition (7): (nd9?1)+(nd10?1)?1.55 are satisfied (where, 16<fT/fW, ?>35, and in the third lens unit: nd8, nd9, nd10 are refractive indices to the d-line of the lens elements located on the most object side and at the second and the third positions from the object side; vd8 is an Abbe number to the d-line of the lens element on the most object side; ? is a half view angle at a wide-angle limit; fT is a focal length of the entire system at a telephoto limit; and fW is a focal length of the entire system at a wide-angle limit).

Abstract: A zoom lens comprising, in order from an object side: a first lens group G1 having positive refractive power; a second lens group G2 having negative refractive power; and a third lens group G3 having positive refractive power; each distance between said lens groups adjacent to each other changing upon zooming from a wide-angle end state to a telephoto end state, said first lens group G1 having a cemented lens including a negative lens L11, and said third lens group G3 having a cemented lens L32 and L33, and a given conditional expression being satisfied, thereby providing a downsized zoom lens having high optical performance.

Abstract: A zoom lens includes a first lens group of negative refractive power, a second lens group of positive refractive power and a third lens group of positive refractive power. The zoom lens satisfies the following condition formulas: 0.68<|f2/f1|<0.85, and 0.65<L2/fT<0.86, where f1 represents an effective focal length of the first lens group, f2 represents an effective focal length of the second lens group, L2 is a displacement of the second lens group when the zoom lens varies from a wide-angle state to a telephoto state, and fT represents an effective focal length of the zoom lens which is in the telephoto state.

Abstract: A zoom lens comprising, in order from an object side thereof, a first lens group of positive refracting power, a second lens group of negative refracting power, an aperture stop, a third lens group of positive refracting power, a fourth lens group of negative refracting power, and a fifth lens group of positive refracting power. Upon zooming from the wide-angle end to the telephoto end, at least the first lens group and the aperture stop remain fixed in position, the second and third lens groups move in the optical axis direction, and the separation between each of the lens groups and the aperture stop changes. Upon focusing from a focusing-on-infinity state to a close-range-focusing state, the fourth lens group moves in the optical axis direction, with satisfaction of the following: ?0.36<f4/f1<?0.05??(1A), where fl and f4 are the focal lengths of the first and fourth lens groups, respectively.

Abstract: A zoom optical system comprising, in order from the object side, a first lens unit with negative power, a second lens unit with positive power, a third lens unit with positive power, and a fourth lens unit, wherein spacing between the first lens unit and the fourth lens unit is fixed to an image surface, and the second lens unit and the third lens unit are moved on an optical axis so as to change spacings between the respective lens units when the magnification of the zoom optical system is changed. The third lens unit comprises lens elements more than three, including an aperture stop, at least a lens element with positive power and at least a lens element with negative power, and the most image-side lens element of the third lens unit is a meniscus lens element with a concave surface facing the image side.

Abstract: A zoom lens system comprises, from an object side to an image side: a first lens unit; a second lens unit; a third lens unit; a fourth lens unit; and a fifth lens unit having positive refractive power, wherein: in zooming from a wide angle end to a telephoto end, the first, the second, the third, and the fourth lens units move so that an interval between the first and the second lens units is larger at the telephoto end than that at the wide angle end, an interval between the second and the third lens units is smaller at the telephoto end than that at the wide angle end, and a distance between the third and the fourth lens units varies; and a focal length of the first lens unit, and focal lengths of an entire system at the wide angle end and the telephoto end are appropriately set.

Abstract: A zoom lens disposed between an object side and an image side and including a first, second, third, and fourth lens group is provided. The first lens group has a negative refractive power and includes a first lens and a prism arranged in sequence from the object side to the image side. The first lens is an aspheric lens. A distance between the first lens and the prism is L, an effective focal length of the zoom lens at a wide-end is fw, and 1.58<L/fw<1.88. The second lens group disposed between the first lens group and the image side has a positive power and includes a first double cemented lens. The third lens group disposed between the second lens group and the image side has a negative power and includes a second double cemented lens. The fourth lens group has a positive power.

Abstract: A zoom lens including, in a sequence from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a succeeding lens group having an overall positive refractive power, and having a high zoom magnification and a compact size.

Abstract: The present invention is directed to an inner focusing macro lens that has a large aperture ratio as expressed by 2.5 or even smaller in F-number and still remains compact, and that is adapted to compensate for spherical aberration, astigmatism, and comatic aberration during photographing throughout the entire object distance ranging from infinity to proximity for an up to 1:1-magnification image. The inner focusing macro lens has the leading or first lens group of positive refractivity, the second lens group of negative refractivity, the third lens group of positive refractivity, and the trailing lens set succeeding to the third lens group in sequence from a position closest to an object being photographed. During focusing from a point infinitely far to that as proximal as desired, the first lens group is static while the second lens group is moved toward the imaging plane, and the third lens group is moved toward the object.

Abstract: A zoom lens includes, sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group. During zooming from a wide angle position to a telephoto position, the interval between the first lens group and the second lens group increases, the interval between the second lens group and the third lens group decreases, and an interval between the third lens group and the fourth lens group varies. The fourth lens group includes, sequentially from the object side, a first sub-lens group having a positive refractive power, a second sub-lens group having a negative refractive power, and a third sub-lens group. The second sub-lens group of the fourth lens group is moved along an optical axis to perform focusing.

Abstract: When focal lengths are discretely set, zoom positions are set, relative to a focal length fr at a position at which a movement direction of a correction group, is reversed, such that a difference value between a focal length which is the closest to the focal length fr and falling between a focal length fw at a wide angle end and the focal length fr, and a next focal length is larger than a difference value between any remaining adjacent focal lengths. By moving from the zoom position of the closest focal length directly to the zoom position of the next focal length, a movement range of the correction group can be made smaller than a movement range in the case where the lens position of the focal length fr is set as the zoom position.

Abstract: Provided is a zoom lens having high optical performance over the entire zoom range. The zoom lens includes a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a negative refractive power, and a fourth lens unit having a positive refractive power, which are provided in order from an object side to an image side. During zooming, intervals between the respective lens units change. A focal length (fW) of the entire zoom lens at a wide angle end, a focal length (f3) of the third lens unit, and a movement amount (m2) of the second lens unit during zooming from the wide angle end to a telephoto end are suitably set.

Abstract: A macro-lens system and a photographing apparatus having the macro-lens system. The macro-lens system includes: first, second, third, fourth, and fifth lens groups which are arranged in order from an object side to an image side, wherein the first lens group has a positive refractive power and is fixed during focusing, the second lens group has a negative refractive power and is moved during focusing, the third lens group has a positive refractive power and is fixed during focusing, the fourth lens group has a positive refractive power and is moved during focusing, and the fifth lens group has a negative refractive power.

Abstract: The present invention is a variable power zoom lens that is suitable to APS-format single-lens reflex cameras. The zoom lens has the foremost or first lens group G1 of positive refractivity, the second lens group G2 of negative refractivity, the third lens group G3 of positive refractivity, and the fourth lens group G4 of positive refractivity disposed in sequence from a position closer to the object toward the image plane, and it meets requirements as defined in conditional formulae as follows: 6<Lw/(Ft/Fw)<10 where Lw is the entire length of the lens optics (i.e., from the front surface of the foremost lens piece to the image plane) at the wide-angle end, Ft is a focal length of the lens optics in whole at the telephoto end, and Fw is the focal length of the lens optics in whole at the wide-angle end.

Abstract: Disclosed are a zoom lens and an imaging apparatus having a high zoom ratio, a small total length, and a small overall size. A zoom lens includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power which are arranged in this order from an object side. A gap between the lens groups is changed to change power. The zoom lens satisfies the following Condition expression 1: 0.05<|f4|/ft<0.25??[Condition expression 1] (where ft indicates the focal length of the entire system at a telephoto end and f4 indicates the focal length of the fourth lens group).

Abstract: A zoom lens includes, in order from an object-side to an image-plane-side: a positive first lens unit; a negative second lens unit; a stop; a positive third lens unit; a negative fourth lens unit; and a positive fifth lens unit, wherein: during zooming, the first lens unit moves along a locus convex toward the image-plane-side, the second lens unit moves toward the image-plane-side, and the stop moves; at the telephoto end compared with the wide angle end, an interval between the first lens unit and the second lens unit increases, an interval between the second lens unit and the third lens unit decreases, and an interval between the aperture stop and the third lens unit decreases, focal lengths of the fourth lens unit, a focal length of an entire system at the telephoto end, and a movement amount of the first lens unit are appropriately set.

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 zoom lens comprises 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, and a rear group including at least one lens unit, in order from an object side to an image side. Each of the lens units is configured to move so that a total lens length at a wide-angle end is longer than that at a telephoto end to perform a zoom operation. A movement amount M1 of the first lens unit at the wide-angle end and the telephoto end with respect to an imaging surface, a focal length f1 of the first lens unit, and focal lengths fw and ft of a whole system at the wide-angle end and the telephoto end are appropriately set.

Abstract: A zoom lens includes, sequentially from an object side, a positive first lens group; a negative second lens group; a positive third lens group; and a positive fourth lens group, where 2.0?D23W/FW?3.0 is satisfied. D23W is an interval, at a wide angle edge, between a lens that among lenses of the second lens group, is farthest on an imaging plane side and a lens that among lenses of the third lens group, is farthest on the object side. FW is a focal length of an optical system of the zoom lens at infinity focus, at the wide angle edge.

Abstract: A vari-focal length lens system includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power. In the second lens group, each of the object-side surface of the negative lens arranged on the object side and the object-side surface of the positive lens is formed in an aspherical shape and satisfies the following conditional expression: 2.0<f1/(fw·ft)1/2<2.5 wherein f1 is a focal length of the first lens group, fw is a focal length in the whole lens system in a wide angle end state, and ft is a focal length in the whole lens system in a telephoto end state.

Abstract: A zoom lens system of the present invention has a plurality of lens units each composed of at least one lens element and, in order from the object side to the image side, comprises: a first lens unit having negative optical power and composed of two lens elements; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming, at least the first lens unit and the second lens unit move along an optical axis, on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming, the second lens unit moves in a direction perpendicular to the optical axis, and the condition is satisfied: 1.00<(1?m2W)×m3W<1.50 where, Z=fT/fW>4.

Abstract: A zoom lens comprises, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit, and a fourth lens unit having a positive refractive power. The fourth lens unit includes a forty-first lens unit having a negative refractive power and arranged at the object side with reference to the longest air gap and a forty-second lens unit having a positive refractive power and arranged at the image side with reference to the air gap. The forty-first lens unit includes a negative 411st lens, and the forty-second lens unit includes a positive 421st lens. Abbe numbers and partial dispersion ratios of materials of the 411st lens and the 421st lens ?d411, ?gF411, ?d421 and ?gF421 are appropriately set.

Abstract: A light modulation panel is inserted into an optical path of an imaging lens composed of an image-forming optical system to make the imaging lens function as a depth-of-field-extended optical system. The light modulation panel has power that makes a peak position of defocus MTF when the imaging lens is used alone to function as the image-forming optical system and a peak position of defocus MTF when the imaging lens functions as the depth-of-field-extended optical system by insertion of the light modulation panel into the optical path of the imaging lens coincide with each other.

Abstract: A zoom lens includes, in order from an object side to an image plane side, a first lens group fixed to the image plane during zooming, having a positive refractive power, and including a single lens having a negative refractive power, an optical path change member for changing an optical path, and a positive lens group having a positive refractive power, which are arranged in order from the object side, a second lens group having a negative refractive power and including a negative lens group and a positive lens group which are arranged in order from the object side with an air gap, a third lens group fixed to the image plane during zooming and having a positive refractive power, and at least one lens group having a positive refractive power. The zoom lens satisfies the conditions the 1.4<|fLG1/fw|<5.8 and ?4.8<Ept/Yimg<?2.5.

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 for projection includes a negative first group composed of two lenses, a second group composed of a positive lens, an aperture stop, a third group composed of a positive lens, a fourth group composed of a negative fourth-group-first lens, a fourth-group-second lens arranged in such a manner that a negative air lens is formed between the fourth-group-first lens and the fourth-group-second lens, and a positive fourth-group-third lens, and a fifth group composed of a positive lens having a convex surface facing the magnification side of the zoom lens, which are arranged in this order from the magnification side. Further, the following formula (1) is satisfied: ?0.6<(R72+R71)/(R72?R71)<0.6??(1), where R71 is a radius of curvature of a magnification-side surface of the fourth-group-third lens, and R72 is a radius of curvature of a reduction-side surface of the fourth-group-third lens.

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: A compact wide-angle zoom lens and an image pickup device having the same. The zoom lens includes a first lens group having a negative refractive power and a second lens group having a positive refractive power in an order from an object side to an image side, performs zooming by varying a distance between the first and second lens groups, and performs focusing by using a first lens closest to the object side in the second lens group.

Abstract: A zoom lens includes a first lens unit with a negative refractive power, a second lens unit with a positive refractive power, and a third lens unit with a positive refractive power in order from the object side to the image side. The first lens unit includes a negative lens and a positive lens. When the curvature radius of the object side surface and that of the image side surface of the negative lens are respectively defined as R11 and R12 and the curvature radius of the object side surface and that of the image side surface of the positive lens are respectively defined as R21 and R22, the following conditional expression is satisfied: ?5.6<(R12+R21)/(R12?R21)<?4.7 and 1.5<(R11+R22)/(R11?R22)<2.3.

Abstract: In a zoom lens ZL1 having a plurality of lens groups G1 to G2 which are disposed in order from an object, where a refractive index average value of the lens components which constitute the zoom lens ZL1 is defined as ndav and a refractive index average value of the lens components which constitute the first lens group G1 which is disposed to closest to the object among the plurality of lens groups G1 to G2 is defined as ndGlav, the zoom lens ZL1 is constituted to satisfy the conditional expression ndav?1.80 and to satisfy the conditional expression ndGlav?1.85.

Abstract: Disclosed herein is a zoom lens including a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group. The zoom lens satisfies following conditional expressions (1) and (2), 0.03<H1?/f1<0.3??(1) 0.3<|f2|/?(fw·ft)<0.65??(2) where H1? is an interval from a vertex of a surface nearest to the image side in the first lens group to a principal point on the image side of the first lens group (? denotes the object side, and + denotes the image side), f1 is focal length of the first lens group, f2 is focal length of the second lens group, fw is focal length of an entire lens system at a wide-angle end, and ft is the focal length of the entire lens system at a telephoto end.

Abstract: A zoom lens system, in order from an object side to an image side, comprising a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit of positive power, wherein in zooming, the first to the fourth lens units are moved along the optical axis such that the air spaces between the individual lens units should vary, so that magnification change is achieved, and wherein the conditions: ?0.60<M2/fG2<?0.07, ?W?30, and fT/fW?4.5 (M2 is an amount of axial movement of the second lens unit in zooming, fG2 is a composite focal length of the second lens unit, ?W is a half view angle at a wide-angle limit, and fT and fW are focal lengths of the entire system at a telephoto limit and at a wide-angle limit, respectively) are satisfied, an imaging device and a camera are provided.

Abstract: A zoom lens includes, in order from an object side to an image 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. The zoom lens changes the distances between the lens units during zooming. The following condition is satisfied: 0.3<|f1/fT<0.5 2.3<|f1/fw<3.5, where f1 is a focal length of the first lens unit, fT is a focal length of the zoom lens at a telephoto end, and fw is a focal length of the zoom lens at a wide-angle end.

Abstract: A variable power optical system is provided and includes: in order from the object side, a first lens group having a negative refractive power and including a negative lens group and a positive lens group; a stop; and a second lens group having a positive refractive power and includes a sub-lens group having a positive refractive power as a whole and arranged on the most object side, the sub-lens group including a first lens having a positive refractive power having at least one aspherical surface, a second lens having a negative refractive power, and a third lens having a positive refractive power. The second lens group is moved to the object side along an optical axis to perform a variable power operation from the wide angle end to the telephoto end with moving the first lens group to make a correction of an image plane position.

Abstract: A zoom lens ZL installed in a single-lens reflex digital camera 1 and the like includes, in order from an object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and a rear lens group GR having positive refractive power. The second lens group G2 includes at least one positive lens and a negative lens disposed adjacent to the object side of the positive lens having largest refractive power among the positive lenses. Each distance between lens groups varies upon zooming from a wide-angle end state and a telephoto end state. Thereby providing a zoom lens having excellent optical performance, an optical apparatus equipped the zoom lens, and a method for manufacturing the zoom lens.

Abstract: A zoom lens includes, in order from an object side to an image 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. The zoom lens changes the distances between the lens units during zooming. The following condition is satisfied: 0.3<|f1 |/fT<0.5, where f1 is a focal length of the first lens unit, and fT is a focal length of the zoom lens at a telephoto end.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. In the zoom lens, an interval between the first and second lens units becomes smaller at a telephoto end than at a wide-angle end during zooming. The first lens unit includes, in order from the object side to the image side, a first lens having a negative refractive power, a second lens having a negative refractive power, which is made of a plastic and has an aspheric lens surface, and a third lens unit having a positive refractive power. In the zoom lens, a refractive index and an Abbe number of the plastic (Nd, ?d), a focal length of the second lens (fn), and a focal length of the first lens unit (f1) are appropriately set.

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: 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 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: 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 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 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 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 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: 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 has a field view of 60° to 70° at a wide-angle end, a magnification change ratio of about five to six times, and a small number of component lenses, enables retraction to a compact size when not in use, provides high resolution, and is compatible with a compensation function for zoom lens vibrations. Comprised are, in order from an object side, a first lens unit (G1) of positive optical power, a second lens unit (G2) of negative optical power, a third lens unit (G3) of positive optical power, and a fourth lens unit (G4) of positive optical power. When zooming from the wide-angle end to a telephoto end, the first lens unit (G1) and the second lens unit (G2) move so as to trace a convex path toward an image side, and the third lens unit and the fourth lens unit (G4) move monotonously toward an object side.