Abstract: A zoom lens includes, 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, and a third lens unit having a positive refractive power. In the zoom lens, during zooming, each lens unit is configured to move such that distances among the lens units vary. The first lens unit consists of three lenses. A relative partial dispersion ?gF and an Abbe number ?d of a material of the positive lens included in the first lens unit are appropriately set by satisfying predetermined mathematical conditions.

Abstract: Disclosed is a zoom lens system including a first lens unit having a positive optical power, a second lens unit having a negative optical power, and a rear unit including at least one lens unit, which are disposed in the stated order from an object side to an image side. At least two lens units move for zooming so that a distance between adjacent lens units is changed. In this zoom lens system, the first lens unit includes a composite optical element in which a first optical element having a positive optical power and a second optical element having a negative optical power are cemented to each other. Refractive indexes and Abbe numbers of materials of the first optical element and the second optical element are set appropriately so that high optical performance is realized.

Abstract: A zoom device for a lighting fixture has a first lens assembly of positive refractive power; a second lens assembly of negative refractive power; and a third lens assembly of positive refractive power. The first lens assembly, second lens assembly, and third lens assembly are aligned along a longitudinal axis coincident with the axis of a light beam emitted by a light source of the lighting fixture, and are characterized by respective focal lengths, which are such as to effectively adjust the size of the images projected by the lighting fixture, while at the same time maintaining compactness of the zoom device.

Abstract: Embodiments of an optical zoom lens system may comprise three lens groups with a PNP power sequence. The first lens group may vary focus. The second and third lens groups may be movable to vary magnification during zoom. The first lens group may include three lens subgroups with an NNP power sequence: a stationary first lens subgroup, a second lens subgroup including a movable lens element, and a stationary or movable third lens subgroup. The second lens subgroup may include two parts, which may be movable at different rates of travel to vary focus. One part may include the movable lens element. Lens elements of the first lens group may be movable according to different focus movement plans. In the first lens group, lens element movement and lens element power may contribute to provide low focus breathing over the entire zoom range. The F-number may be F/2.8 or less.

Abstract: An endoscope objective optical system used in an endoscope has an objective optical system including a first lens group having a positive refractive power, an aperture stop, a second lens group having a negative refractive power and a third lens group having a positive refractive power, the first lens group, the aperture stop and the second and third lens group being successively disposed from the object side. The second lens group is made movable along an optical axis to change the focal length of the objective optical system. The lens surface at the object-side outermost position in the first lens group is formed so as to be convex on the object side.

Abstract: An imaging unit includes: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; and a solid-state imaging device that images an optical image formed by the first lens group to the third lens group sequentially arranged from an object side toward an image side, wherein, at zooming from a wide-angle end to a telephoto end, a distance between the first lens group and the second lens group becomes larger and a distance between the second lens group and the third lens group becomes smaller, and a distance from the second lens group to the solid-state imaging device at the wide-angle end is the longest in all zoom positions.

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: An image forming optical system includes in order from an object side to an image surface, a first lens group having a positive refracting power, a second lens group having a negative refracting power, and a third lens group having a positive refracting power. At the time of zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group increases, and a distance between the second lens group and the third lens group decreases. The first lens group has a cemented lens which includes a first lens element E1, a second lens element E2, and a third lens element E3. In the cemented lens, the first lens element E1 is cemented to a surface on one side of the second lens element E2, and the third lens element E3 is cemented to another surface of the second lens element E2. The first lens element E1 is a negative lens, and the second lens element E2 is a positive lens. The image forming optical system satisfies predetermined conditional expressions.

Abstract: Embodiments of an optical zoom lens system may comprise three lens groups with a PNP power sequence. The first lens group may vary focus. The second and third lens groups may be movable to vary magnification during zoom. The first lens group may include three lens subgroups with an NNP power sequence: a stationary first lens subgroup, a second lens subgroup including a movable lens element, and a stationary or movable third lens subgroup. The second lens subgroup may include two parts, which may be movable at different rates of travel to vary focus. One part may include the movable lens element. Lens elements of the first lens group may be movable according to different focus movement plans. In the first lens group, lens element movement and lens element power may contribute to provide low focus breathing over the entire zoom range. The F-number may be F/2.8 or less.

Abstract: A zoom lens system includes, in order from an object side, a first lens unit G1 having a positive refracting power, a second lens unit G2 having a negative refracting power, a third lens unit G3 having a positive refracting power, and a fourth lens unit G4 having a positive refracting power, and at the time of zooming from a wide angle end to a telephoto end, a space between the lens units changes, and the second lens unit includes not more than three lenses, and a biconcave negative lens which satisfies the following conditional expression (1) is disposed nearest to the object side, in the second lens unit, and (the zoom lens system) is characterized by satisfying the following conditional expression (2) ?0.1<SF2n1<0.5??(1) 3.0<ft/fw<12.0??(2).

Abstract: An image processing apparatus includes: a table generation unit that generates a table in which a coefficient set including predetermined weighting coefficients and pixels contained in a resolution converted image are related to each other on the basis of a size of an input image and a size of a resolution converted image; a coefficient selecting unit that selects a coefficient set to be applied for a calculation of a pixel value in the resolution converted image out of plural coefficient sets on the basis of a table generated by the table generation unit; and a pixel value calculating unit that calculates pixel values to be used in the resolution converted image resulting from the resolution conversion of the input image on the basis of the coefficient set selected by the coefficient selecting unit and plural pixel values contained in the input image.

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 zoom lens including, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, an image side lens group having a positive refractive power, wherein the distance between the first lens group and the second lens group changes during zooming, a refractive optical element A, which has a positive refractive power when its object side surface and image side surface are exposed to air, is provided in the first lens group and located closest to the object side in the first lens group, and the refractive optical element A is cemented together with an optical element B. The Abbe constant ?d and the partial dispersion ratio ?gF of the refractive optical element A satisfies certain conditions.

Abstract: An image forming optical system includes in order from an object side to an image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and an image-side lens group having a positive refractive power. A distance between the first lens group and the second lens group changes at the time of zooming. A refractive optical element A having a positive refractive power is positioned in the first lens group. The image forming optical system satisfies the following conditional expression (1-1), conditional expression (1-2), and conditional expression (2). ?dA<30??(1-1) 0.54<?gFA<0.9??(1-2) |fG1/fG2|>6.4??(2).

Abstract: A zoom lens includes first, second, and third lens groups having positive, negative, and positive refractive powers, respectively, which are arranged in order from the object side to the image side. When zooming from wide-angle to telephoto, the first lens group moves to the object side, and spacings between the lens groups change. The third lens group has at least two lenses including a positive lens arranged closest to the object side. Blur correction on the image plane is performed by moving the positive lens of the third lens group perpendicularly to the optical axis. The zoom lens satisfies the following conditional expression (1): 0.3<(1??kFW)·?kRW<1.9??(1) where ?kFW and ?kRW are respectively the lateral magnifications at wide-angle of the positive lens arranged closest to the object side in the third lens group, and of a lens group including all lenses arranged closer to the image side than the positive lens.

Abstract: Including, in order from an object side: a first lens group G1 having positive power; a second lens group G2 having negative power; a third lens group G3 having positive power; a fourth lens group G4 having negative power; and a fifth group G5 having positive power, an aperture stop being disposed to an image side of the second lens group, upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group G1 and the second lens group G2 increasing, a distance between the second lens group G2 and the third lens group G3 decreasing, a distance between the third lens group G3 and the fourth lens group G4 varying, and a distance between the fourth lens group G4 and the fifth lens group G5 varying, and given conditionals being satisfied, thereby providing a zoom lens system having high optical performance with suppressing variation in aberrations, an optical apparatus equipped therewith, and a method for manufacturing the zoom lens system.

Abstract: The zoom lens is a retractable bent-type zoom lens capable of providing a high zoom ratio and a reduced thickness, and capable of retracting into a camera body with an easily-configured mechanism. The zoom lens includes 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 prism including a reflective surface, and a posterior lens group which includes plural lens units and has as a whole a positive refractive power. The first and second lens units are retractable into a space formed by movement of the prism in a direction orthogonal to an optical axis of the first lens unit, and, during zooming, the second lens unit and the plural lens units in the posterior lens group are moved while the first lens unit and the prism are fixed.

Abstract: The invention relates to an eyepiece optical system that, albeit being of small size, works in favor of gaining an angle of field and optical performance, and an electronic view finder incorporating such an eyepiece optical system. Specifically, the invention is characterized by comprising, in order from an object side to an exit side thereof, a first lens group that is a single lens that has positive refracting power and is in a meniscus configuration concave on its object side, a second lens group that is a single lens that has negative refracting power and is in a meniscus configuration concave on its object side, and a third lens group that is a single lens that has positive refracting power, wherein an object-side concave lens surface in the first lens group is an aspheric surface, an object-side concave lens surface in the second lens group is an aspheric surface, and an exit-side lens surface in the third lens group is an aspheric surface.

Abstract: A zoom lens is composed, in order from the object side thereof, of a front side lens unit having a negative refracting power at the wide angle end and a rear side lens unit having a positive refracting power at the wide angle end. The front side lens unit includes a first lens unit located closest to the object side and having a positive refracting power and a second lens unit located on the image side of the first lens unit and having a negative refracting power. The distance between the first lens unit and the second lens unit is larger at the telephoto end than at the wide angle end. The rear side lens unit includes a third lens unit located closer to the object side at the telephoto end than at the wide angle end and having a positive refracting power, the distance between the third lens unit and the second lens unit being smaller at the telephoto end than at the wide angle end. The third lens unit satisfies the following condition: 0.01<f3/ft<0.16 . . . (1).

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 system comprises, in order from an object, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The first lens group has a first-a partial lens group and a first-b partial lens group arranged on an image side of the first-a partial lens group with an air space and is constructed such that the first-b partial lens group moves along an optical axis direction upon focusing from infinity to a close-range object. The third lens group is constituted by a third-a partial lens group having a positive refractive power and a third-b partial lens group having a negative refractive power arranged on the image side of the third-a partial lens group with an air space.

Abstract: A zoom lens including: 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, wherein the first lens group, the second lens group, the third lens group, and the fourth lens group are sequentially arranged in the order from an object side to an image surface side, while zooming from a wide-angle position to a telephoto position, the first lens group is moved in such a way that the distance between the first lens group and the second lens group is widened, the second lens group is moved along a trajectory convex toward the image surface side, the third lens group is moved from the image surface side to the object side, and the fourth lens group is moved along a trajectory convex toward the object side, and the zoom lens satisfies the following inequalities: vd1ave>68.2, and Nd1ave>1.

Abstract: A zoom lens system comprises, in order from an object, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. The first lens group has a first-a partial lens group and a first-b partial lens group arranged on an image side of the first-a partial lens group with an air space and is constructed such that the first-b partial lens group moves along an optical axis direction upon focusing from infinity to a close-range object. The third lens group is constituted by a third-a partial lens group having a positive refractive power and a third-b partial lens group having a negative refractive power arranged on the image side of the third-a partial lens group with an air space.

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 the object side thereof, a first lens unit G1 having a positive refracting power, a second lens unit G2 having a negative refracting power, and a third lens unit G3 having a positive refracting power, wherein zooming is performed by changing distances between the lens units, the second lens unit has two negative lens elements and one positive lens element, and the lens element located closest to the object side is a negative lens element. The zoom lens satisfies the following conditions: 0.60<?d2G/Imw<1.95??(1-1) and 1.830<N2ave<2.000??(1-2), where the term “lens element” refers to an optical member that satisfies 0.1<L/Imw.

Abstract: In a zoom lens, in which the distance between the first lens group and the second lens group changes during zooming, wherein a refractive optical element A that has a positive refracting power if its object side surface and its image side surface are interfaces with air is provided between an object side base optical element B and an image side base optical element C to constitute therewith a three-piece cemented optical element D in the first lens group, there is at least one optical element having a positive refracting power disposed closer to the object side than the three-piece cemented optical element D, and the zoom lens satisfies a certain condition.

Abstract: A zoom lens which includes in order from an object side to an image side: a first lens unit with a positive refractive power; a second lens unit with a negative refractive power; and a subsequent lens unit. The second lens unit moves on an optical axis to increase an interval between the first and second lens units during zooming from a wide angle end to a telephoto end. The first lens unit includes a front side lens subunit immovable during focusing with a positive refractive power and a rear side lens subunit movable during focusing with a positive refractive power. A PR lens of the rear side lens subunit and a N2 lens of the second lens unit are made of a material wherein an Abbe number (?d) and a partial dispersion ratio (?gF) are suitably set.

Abstract: An optical system includes a first optical element and a second optical element on at least one of an enlargement side and a reduction side relative to a point P at which a light axis and a paraxial chief ray intersect. Each of the first optical element and second optical element is composed of a solid material having a refractive light incident surface and a refractive light emergent surface. The optical system satisfies the following conditional expressions: ??gF1>0.0272, ??gF2<?0.0278, and f1×f2<0 where ??gF1 and ??gF2 denote anomalous partial dispersion values of the first and second optical elements for the g-line and F-line, respectively, and f1 and f2 denote focal lengths of the first and second optical elements, respectively, when the light incident surfaces and the light emergent surfaces of the first and second optical elements are in contact with air.

Abstract: A small-sized and low-cost infrared zoom lens while maintaining the brightness of an image and relevant arts to the infrared zoom lens is provided. The infrared zoom lens 1a is made up of first to third lens groups G1 to G3 formed of zinc sulfide. The first lens group G1 is made up of one or two lenses and has a positive refractive power. The second lens group G2 is made up of one or two lenses and has a negative refractive power. The third lens group G3 is made up of two or more lenses and has a positive refractive power as the whole lens group and also includes a positive meniscus lens with a convex face pointed at the object side as a final lens on the image surface side. At the zooming time, the second lens group G2 is moved along the optical axis. At least one of the lens surfaces of the first to third lens groups G1 to G3 is a diffraction surface. At least one of the lens surfaces of the first and third lens groups G1 and G3 is an aspheric surface.

Abstract: A zoom device for a lighting fixture has a first lens assembly of positive refractive power; a second lens assembly of negative refractive power; and a third lens assembly of positive refractive power. The first lens assembly, second lens assembly, and third lens assembly are aligned along a longitudinal axis coincident with the axis of a light beam emitted by a light source of the lighting fixture, and are characterized by respective focal lengths, which are such as to effectively adjust the size of the images projected by the lighting fixture, while at the same time maintaining compactness of the zoom device.

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: A zoom lens system includes a positive first lens group, a negative second lens group, and a rear lens group which is provided on the image side of the negative second lens group, and has a combined positive refractive power, in this order from the object; and the zoom lens system satisfies the following conditions: 5.0<f1/fw<6.5 ??(1) 0.4<fRt/ft<0.55 ??(2) wherein f1 designates a focal length of the positive first lens group; fw designates a focal length of the entire the zoom lens system at the short focal length extremity; fRt designates a combined focal length of the positive rear lens group at the long focal length extremity; and ft designates a focal length of the entire zoom lens system at the long focal length extremity.

Abstract: An electronic imaging apparatus comprises a zoom lens including at least two lens groups and adapted to implement zooming by changing the spacing between the respective lens groups, and an electronic imaging device. The zoom lens includes at least one positive lens on an imaging device side with respect to an aperture stop, and satisfies the following conditions (1), (2) and (3). |?t??w|>8??(1) 1.0×10?3<P<4.0×10?3??(2) 4<ft/fw<50??(3).

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: An image forming optical system includes in order from an object side to an image surface, a first lens group having a positive refracting power, a second lens group having a negative refracting power, and a third lens group having a positive refracting power. At the time of zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group increases, and a distance between the second lens group and the third lens group decreases. The first lens group has a cemented lens which includes a first lens element E1, a second lens element E2, and a third lens element E3. In the cemented lens, the first lens element E1 is cemented to a surface on one side of the second lens element E2, and the third lens element E3 is cemented to another surface of the second lens element E2. The first lens element E1 is a negative lens, and the second lens element E2 is a positive lens. The image forming optical system satisfies predetermined conditional expressions.

Abstract: A relay finder optical system, of a single-lens reflex camera, includes a condenser lens group, a prism, and a relay lens group, in this order from a primary imaging plane. An image, which is formed on the primary imaging plane, and is upside down and inverted from left to right, is re-formed on a secondary imaging plane for viewing by a photographer. The relay lens group includes a positive front lens group, a negative intermediate lens group, and a positive rear lens group, in this order from the object.

Abstract: A zoom lens system includes a rear lens group having in order from an object side, a first lens unit G1 having a positive refracting power, a second lens unit G2 having a negative refracting power, and a third lens unit G3 having a positive refracting power, and an aperture stop S which is disposed between the second lens unit G2 and the third lens unit G3. At the time of zooming from a wide angle end to a telephoto end, when focused on an object at a longest distance, each of the first lens unit G1 , the second lens unit G2, and the third lens unit G3 moves such that a distance between the first lens unit G1 and the second lens unit G2 is widened (increased), and a distance between the, second lens unit G2 and the third lens unit G3 is narrowed (decreased).

Abstract: In a zoom lens system, at a time of zooming from a wide angle end to a telephoto end, when focused on an object at a longest distance, at the telephoto end, a first lens unit moves to be positioned more toward an object side, than at a wide angle end, at the telephoto end, a second lens unit moves to be positioned more toward an image side, than at the wide angle end, at the telephoto end, an aperture stop and a third lens unit moves to be positioned more toward the object side, than at the wide angle end, and a combined system of the first lens unit and the second lens unit at the wide angle end has a negative refracting power, and at the time of zooming from the wide angle end to the telephoto end, the second lens unit is positioned more toward the object side than a position of the second lens unit at the wide angle end, and the first lens unit moves to be positioned more toward the object side, than at the wide angle end, at the intermediate zoom state, and in the intermediate zoom state, the aperture sto

Abstract: A zoom lens comprises, in order from its object side, a first lens group of positive refracting power, a second lens group of negative refracting power, and a third lens group of positive refracting power located on an image side with respect to the second lens group. Upon zooming from the wide-angle end to the telephoto end, the spacing between the first lens group and the second lens group grows wider at the telephoto end than at the wide-angle end, and the spacing between the second lens group and the third lens group becomes narrower at the telephoto end than at the wide-angle end. The first lens group comprises a negative lens and a positive lens, and the number of the negative lens in the first lens group is only one. At least one positive lens in the first lens group satisfies the following conditions (1) and (2): 1.80<ndlp<2.0??(1) 50.0<?dlp<70.

Abstract: A zoom optical system at least includes in the order from an object side: a first lens group having a positive optical power; a second lens group having a negative optical power; and a third lens group having a positive optical power. In zooming from a wide angle end to a telephoto end, a distance between the first lens group and the second lens group is increased, and a distance between the second lens group and the third lens group is decreased. The first lens group includes at least one negative lens element, and the second lens group includes a negative lens element closest to the object side, with a lens surface of the negative lens element being concave toward an image side.

Abstract: A zoom lens system according to the present invention comprises a plurality of lens units, in order from an object side to an image side, including at least: a first lens unit having positive optical power; a second lens unit having negative optical power; and a third lens unit having positive optical power, wherein magnification change is performed by changing an interval between the individual lens units, wherein the second lens unit, in order from the object side to the image side, comprises: a lens element A having negative optical power; a lens element B that has an aspheric surface and has negative optical power; and a lens element C having positive optical power, and wherein the second lens unit satisfies the following conditions (1): 1.85<NdA<2.20 and (2): 1.88<NdC<2.20, where NdA is the refractive index to the d-line of the lens element A and NdC is the refractive index to the d-line of the lens element C.

Abstract: A compact zoom lens system has a zoom ratio of about 3.5 or more, an angle of view of 29° or more in a wide-angle end, and a vibration reduction function. The system includes, in order from an object, a first group having positive power, a second group having negative power, and a third group having positive power. Upon zooming from a wide-angle end to a telephoto end, a distance between the first and second groups increases, and a distance between the second and third groups decreases. The third group consists of, in order from the object, a 31 group having positive power, a 32 group having negative power, and a 33 group. Only the 32 group is moved perpendicularly to an optical axis for correcting image blur due to camera shake.

Abstract: The invention provides a zoom lens including at least 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, in order from an object side, and an aperture stop between the second lens group and the third lens group, wherein, in changing magnification from a wide angle end toward a telephoto end, at least the first lens group and the third lens group move toward the object side so as to increase a spacing between the first lens group and the second lens group, and to decrease a spacing between the second lens group and the third lens group.

Abstract: An optical system includes a first optical element and a second optical element on at least one of an enlargement side and a reduction side relative to a point P at which a light axis and a paraxial chief ray intersect. Each of the first optical element and second optical element is composed of a solid material having a refractive light incident surface and a refractive light emergent surface. The optical system satisfies the following conditional expressions: ??gF1>0.0272, ??gF2<?0.0278, and f1×f2<0 where ??gF1 and ??gF2 denote anomalous partial dispersion values of the first and second optical elements for the g-line and F-line, respectively, and f1 and f2 denote focal lengths of the first and second optical elements, respectively, when the light incident surfaces and the light emergent surfaces of the first and second optical elements are in contact with air.

Abstract: A zoom lens includes a positive first lens unit G1, a negative second lens unit G2 and a rear group having a positive refracting power having at least one lens unit. The lens unit located closest to the object side in the rear grout is a third lens unit G3 having a positive refracting power. The zoom lens has an aperture stop S disposed closer to the image side than the second lens unit G2 and closer to the object side than the lens surface located closest to the image side in the third lens unit G3. The zoom lens satisfies a prescribed conditional expression.

Abstract: The invention relates to a zoom lens which, albeit being of simplified construction, makes sure brightness and holds back fluctuations of astigmatism, and facilitates making sure being fast and the angle of view and the zoom ratio at the wide-angle end. The zoom lens comprises a first group G1 of positive power, a second group G2 of negative power and a third group G3 of positive power, with a stop S between the second group G2 and the third group G3. Upon zooming from the wide-angle end to the telephoto end, the first group G1, the second group G2, and the third group G3 moves; the second group G2 moves toward the object side after moving toward the image side; the first group G1 and the third group G3 are positioned on the object side at the telephoto end with respect to the wide-angle end.

Abstract: A zoom lens achieves a high zoom ratio and high optical performance in an entire zoom range. The zoom lens includes, 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, and a rear unit which includes at least one lens unit. At least the second lens unit is moved during zooming such that a distance between the first and second lens units is larger at a telephoto end than at a wide-angle end. The first lens unit includes at least a first lens element made of a material which satisfies Nd1a>2.3?0.01·?d1a and 1.65<Nd1a<2.70. The first and second lens units satisfy 2.5<|f1/f2|<12.0.

Abstract: A zoom lens system has a front lens group and a rear lens group along the optical axis and in order from the object side. The rear lens group has a first lens unit having a positive refracting power, a second lens unit having a negative refracting power, and a third lens unit having a positive refracting power. Upon zooming from a wide-angle end state to a telephoto end state, a space between the front lens group and the first lens unit varies, a space between the first lens unit and the second lens unit increases, and a space between the second lens unit and the third lens unit decreases. At least a part of the second lens unit is movable so as to have a component in a direction perpendicular to the optical axis.

Abstract: An image pickup apparatus, which comprises, in order from the object side, an aperture member having an opening section, a zoom lens changing a magnification by properly changing distances between a plurality of lens units, and an image pickup device, is provided with a flare stop which has an opening section with a set shape and is integrated with the most object side lens unit in the plurality of the lens units, the opening section of the aperture member does not intercept an effective light beam in the wide-angle position and intercepts a part of the effective light beam in the telephoto position, and the flare stop does not intercept in the wide-angle position the effective light beam having passed through the opening section of the aperture member and intercepts in the telephoto position a light ray which is included in the effective light beam passing through the opening section of the aperture member and strikes the edge of the opening section of the aperture member to be scattered.

Abstract: A zoom lens system includes, 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, and a subsequent lens-unit set including at least one lens units. Intervals between the lens units change during zooming. The first lens unit includes a negative lens element, an optical element, and a positive lens element. Various parameters are set appropriately, including the Abbe number ?n and the partial dispersion ratio ?gF of a material composing the optical element, the focal length f1n of the negative lens element and the Abbe number ?1n of a material composing the negative lens element, the focal length f1 of the first lens unit, and respective lateral magnifications ?3iw and ?3it of the subsequent lens-unit set at a wide-angle end and at a telephoto end.