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 among the lens units is changed so that an optical image of an object is formed with a continuously variable magnification, a first lens unit arranged on the most object side among the lens units includes a lens element having a reflecting surface for bending a light beam from the object, and any one of the lens units, any one of the lens elements, or alternatively a plurality of adjacent lens elements that constitute one lens unit move in a direction perpendicular to an optical axis; an imaging device including the zoom lens system; and a camera employing the imaging device.

Abstract: A zoom lens and an imaging apparatus are disclosed. The zoom lens includes, in order from an object side to an image-plane 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, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power. During a change of a lens zoom position from a maximum wide angle state to a maximum telephoto state, at least the second lens group moves toward an image side, the third lens group moves toward an object side, and the fourth lens group is fixed in an optical-axis direction. An aperture stop is disposed near the object side of the third lens group. The first to fifth lens groups satisfy predetermined conditions.

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 a first negative lens group, a second negative lens group, a third positive lens group, an aperture diaphragm, and a fourth positive lens group arranged in this order from an object side. When power varies from a wide angle end to a telephoto end, the first and second lens groups are moved to an image surface along an optical axis and then moved to the object side. The third and fourth lens groups are moved to only the object side along the optical axis. The first lens group includes at least one aspheric lens, and the aspheric lens has an aspheric shape in which a positive refractive power is increased toward the periphery of the lens when a paraxial refractive power is positive and a negative refractive power is decreased toward the periphery of the lens when the paraxial refractive power is negative.

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 among the lens units is changed so that an optical image of an object is formed with a continuously variable magnification, a first lens unit arranged on the most object side among the lens units includes a lens element having a reflecting surface for bending a light beam from the object, and any one of the lens units, any one of the lens elements, or alternatively a plurality of adjacent lens elements that constitute one lens unit move in a direction perpendicular to an optical axis; an imaging device including the zoom lens system; and a camera employing the imaging device.

Abstract: A zoom lens includes a first lens band having a positive focal length, a second lens band having a negative focal length, and at least third to fifth lens bands having positive focal lengths. An aperture diaphragm is located in the vicinity of the third lens band. When magnification i.e., zooming is performed from short to long focal point ends, the second lens band smoothly moves toward the third lens band and the fourth lens band simultaneously moves from the fifth lens band side toward a long focal point end so as to share a magnification function together with the second lens band.

Abstract: A zoom lens system comprising, in order from an object along an optical axis: a first lens group having a negative refractive power; a second lens group having a positive refractive power; and a third lens group having a positive refractive power; the following conditional expression being satisfied: 0.6<Ymax×ft/f12<1.0 where Ymax denotes the maximum image height of the zoom lens system, ft denotes a focal length of the zoom lens system in a telephoto end state, and f1 denotes a focal length of the first lens group.

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; and a fourth lens group having a positive refracting power; wherein, upon zooming, at least the first lens group and the fourth lens group move to the object side; and wherein, upon focusing, the fourth 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 rear lens group is moved in a direction of an optical axis of the zoom lens.

Abstract: An interchangeable lens unit comprises a second lens group unit, a focus lens unit, a fourth lens group unit, a zoom ring unit, and a focus motor. The zoom ring unit mechanically transmits operational force inputted to a zoom ring to the second lens group unit and the fourth lens group unit. The focus motor electrically drives the focus lens unit in the Z axis direction with respect to the second lens group unit. When the zoom ring is operated in a state in which no power is being supplied to the focus motor, a gap is always ensured in the Z axis direction between the focus lens unit and the second lens group unit.

Abstract: A high zoom-ratio zoom lens system of five lens groups includes a positive first lens group, a negative second lens group, a positive third lens group, a positive fourth lens group, and a negative fifth lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, 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 high zoom-ratio zoom lens system satisfies the following conditions: 5.5<f1/|f2|<10.0(f2<0) ??(1) 1.7<f3/f4<4.0 ??(2) wherein f1 designates the focal length of the first lens group; f2 designates the focal length of the second lens group; f3 designates the focal length of the third lens group; and f4 designates the focal length of the fourth lens group.

Abstract: Disclosed is a projection variable focusing lens and a projection display device that has a reduction side which is telecentric, a high magnifying power, a small size, a light weight, and a low manufacturing cost and is capable of correcting all aberrations occurring when power varies with good balance. A projection variable focusing lens that moves only one lens group when power varies includes a first negative lens group G1, a second positive lens group G2, a third lens group G3, and a fourth positive lens group G4 arranged in this order from a magnification side. When a focal length varies, only the second lens group G2 is moved along an optical axis X. During focusing, the third lens group G3 is moved along the optical axis X. A reduction side is substantially telecentric.

Abstract: Disclosed herein is a zoom lens, wherein a stop moves in an optical axis direction n in a phase of zooming; a position of the stop in a telephoto end is located on an object side with respect to a position of the stop in a wide-angle end; an opening size of the stop is controlled in conjunction with the zooming so that an open F number becomes approximately constant in a range from the wide-angle end to a specific intermediate focal length; the opening size of the stop is made approximately constant in a range from the specific intermediate focal length to the telephoto end so that the open F number is changed; and the specific intermediate focal length fulfills the following conditional expression (1), wide-angle end focal length×1.5<specific intermediate focal length<telephoto end focal length/1.4 . . .

Abstract: A zoom lens includes, in order from the object side thereof, a first lens unit having a positive refracting power, which is movable during zooming, a second lens unit having a negative refracting power, which is movable during zooming, a third lens unit having a positive refracting power, which is movable during zooming, a fourth lens unit having a positive refracting power, which is movable during zooming, a fifth lens unit having a positive refracting power, which is movable or stationary during zooming. The zoom lens further includes an aperture stop that moves integrally with the third lens unit during zooming. The first lens unit is located closer to the object side at the telephoto end than at the wide angle end, and the third lens unit is located closer to the object side at the telephoto end than at the telephoto end.

Abstract: A zoom lens unit including, in order from an object side to an image surface 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; and a fourth lens group having a positive refracting power, wherein when changing magnification from a wide-angle end to a telephoto end, an interval between the first lens group and the second lens group increases, an 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 increases, wherein when performing focusing on a close range object at least at the telephoto end, with reference to a focused state on an infinite object, the first lens group and the second lens group are fixed, the third lens group is capable of being moved to the image surface side, and the fourth lens group is capable of being moved to the object side.

Abstract: A three-unit zoom lens includes, in order from the object side, a negative first lens unit G1, a positive second lens unit G2 and a third lens unit G3, wherein during zooming from the wide angle end to the telephoto end the distance between the first lens unit G1 and the second lens unit G2 decreases and the distance between the second lens unit G2 and the third lens unit G3 changes. The first lens unit G1 is composed of one negative lens component including, in order from the object side, a negative lens having a concave surface directed toward the image side and a positive lens having a convex surface directed toward the object side. The second lens unit G2 includes at least one negative lens and a plurality of positive lenses, wherein at least three lenses among these lenses are cemented to adjacent lenses, the total number of lens components included in the second lens unit G2 is two or less. The third lens unit is composed of one lens component composed of two or less lenses.

Abstract: A zoom lens in which a lens group located in the vicinity of an aperture stop includes two subgroups and one of the subgroups is shifted so that an image is shifted. An increase in the size of lens groups including a shift lens group can be prevented. In addition, the sensitivity with respect to the axis tilt can be reduced while maintaining a sufficient distance between the two subgroups without increasing the size of the lens groups.

Abstract: Disclosed herein is a zoom lens, including: 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; and a fourth lens group having a positive refracting power; the first, second, third and fourth lens groups being disposed in order from the object side; the first lens group including only a cemented lens including a positive lens and a negative lens cemented in order from the object side and having a generally positive refracting power; the first lens group being configured so as to satisfy the conditional expression (25<?d11??d12<50) where ?d11 is the Abbe number of the positive lens of the first lens group and ?d12 is the Abbe number of the negative lens of the first lens group.

Abstract: An image pickup apparatus having an optical path reflecting zoom lens system includes a zoom lens system, and an image pickup element which is disposed at an image side of the zoom lens system. The zoom lens system includes in order from an object side thereof a first lens unit G1 having a positive refracting power, which includes a reflecting optical member having a reflecting surface which reflects an optical path, a second lens unit G2 having a negative refracting power, a third lens unit G3 having a positive refracting power, a fourth lens unit G4 having a positive refracting power, and an aperture stop S which is disposed between the second lens unit G2 and the fourth lens unit G4. The first lens unit G1 has a position fixed with respect to a position of the image pickup element. At least the second lens unit G2 and the fourth lens unit G4 move and the zooming is carried out from a wide angle end to a telephoto end by changing a distance between each of lens units.

Abstract: A telephoto zoom lens having four lens groups in a P-N-P-P configuration arranged sequentially from an object side. The first lens group includes a front group which is fixed when focusing and has a positive refractive power, and a rear group which moves when focusing and has a positive refractive power. The entire first lens group, including the front and rear groups, is fixed during zooming, and the second and third lens groups move during zooming. The second lens group compensates for shaking of an image plane caused by hand-shaking, by moving in a direction perpendicular to the optical axis, and satisfies the following condition: 1.2<f1a/f1b<1.8 where f1a and f1b denote the focal length of the front group of the first lens group and the focal length of the rear group of the first lens group, respectively.

Abstract: A zoom lens includes, in order from an object side thereof: a first lens group having a negative optical power and comprising a reflection optical element; a second lens group having a positive optical power; a third lens group having a negative optical power; a fourth lens group having a positive optical power; and, a fifth lens group. The first lens group and the fourth lens group are positioned at a fixed distance and at least the second lens group, the third lens group and the fifth lens group move along an optical axis, for varying a power of the zoom lens from a wide-angle end to a telephoto end. The zoom lens satisfies a predetermined expression relating to a focal length of the first lens group, and a focal length of the zoom lens at the wide-angle end.

Abstract: Provided is a zoom lens including 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 having a positive refractive power; and a fourth lens unit having a positive refractive power, each of the first lens unit, the second lens unit, the third lens unit, and fourth lens unit moving to perform zooming, in which M3 representing a moving amount of the third lens unit on an optical axis during zooming from a wide angle end to a telephoto end, Lt representing a total lens length on the telephoto end, f3 representing a focal length of the third lens unit, and ft representing a focal length of an entire lens system on the telephoto end are each appropriately set.

Abstract: A zoom lens for capturing images that enhances the image aberration correction rate to achieve high resolution and zooming ratio. The zoom lens includes, in sequence from an object side to an image side, a first lens group with positive refraction power, a second lens group with negative refraction power, a third lens group with positive refraction power, a fourth lens group with positive refraction power, a fifth lens group with positive refraction power and a sixth lens group with positive refraction power. The positions of first and sixth lens groups are fixed during photographing. When the zoom lens is made to zoom from a wide-angle end to a telephoto end thereof, the second lens group moves toward the image side while the fourth and fifth lens groups move toward the object side. In addition, the zoom lens has a reflection element so as to fold the image light entering thereof.

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=?{square root over ( )}(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 is provided, which includes a first lens group Gr1 having positive refractive power, a second lens group Gr2 having negative refractive power, which is movable in an optical axis direction mainly for zooming (varying power), a third lens group Gr3 having positive refractive power, a fourth lens group Gr4 having negative refractive power, which is movable in the optical axis direction for correcting fluctuations in focal position during zooming and for focusing, and a fifth lens group Gr5 having positive refractive power, which lens groups are arrayed in order from an object side, wherein the first lens group includes a concave lens, a convex lens, and a triple-cemented lens T1 in which a lens L6 made of special low-dispersion glass is sandwiched in the middle, which lenses are arrayed in order from the object side. Thereby, a range from a super wide-angle area to a super telephoto area can be covered with angles of view of not less than 67 degrees at a wide-angle end and not more than 1.

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 positive first lens group G1, a negative second lens group G2, an aperture diaphragm St, a positive third lens group G3, and a positive fourth lens group G4 are sequentially arranged, and a movement of the lens groups and the aperture diaphragm St during zooming is optimized in combination with an appropriate conditional expression. During zooming, a position of the aperture diaphragm St on an optical axis at a wide-angle end is closer to an image plane than that at a telephoto end, and a space on the optical axis at the wide-angle end between the aperture diaphragm St and the third lens group G3 is larger than that at the telephoto end, thereby suppressing the length of the whole lens. Also, heights of rays passing through the first lens group G1 are lowered, thereby suppressing the lens diameter of the first lens group G1.

Abstract: A focus adjustment method of a zoom lens system is provided for correcting a focal point shift caused by manufacturing error. The zoom lens system includes three movable lens groups in which at least two of said lens groups are moved to perform zooming to form an image onto an imaging device. In the zoom lens system, a finite number of focal length positions at which a focus adjustment is performed is provided. The lens group closest to the imaging device out of the three lens groups includes a focusing lens group. A position of the focusing lens group is controlled via pulses of a stepping motor. The focus adjustment method includes the combination of performing the above control of the focusing lens group to determine a position of the focusing lens group via pulses of the stepping motor and determining an amount of adjustment of the imaging device.

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 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: 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 negative optical power; and at least one subsequent lens unit, wherein at the time of zooming, all lens units move in a direction along the optical axis so that intervals between the lens units vary, and at the time of focusing, a lens unit included in the at least one lens unit moves in a direction along the optical axis.

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 three subsequent lens units, the at least three subsequent lens units, in order from an object side to an image side, include: a lens unit A having negative optical power; and a lens unit B having positive optical power and arranged on the image side of 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, and at the time of focusing, the lens unit A moves in a direction along the optical axis.

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 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: 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 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 at the time of zooming, all lens units move in a direction along the optical axis so that intervals between the lens units vary, and at the time of focusing, a second most image-side lens unit moves in a direction along the optical axis.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. Upon zooming from the short focal length extremity to the long focal length extremity, each of the first to third lens groups move along the optical axis. The first lens group includes a negative first sub-lens element, a second sub-lens element having a negative and weak refractive power and at least one aspherical surface, and a positive third sub-lens element. The zoom lens system satisfies the following condition: 0.5<(ra?rb)/(ra+rb)<1.2 ??(1) wherein ra designates the radius of curvature of the object-side surface of the second sub-lens element; and rb designates the radius of curvature of the image-side surface of the second sub-lens element.

Abstract: The present invention relates to a low-cost zoom lens which has high optical performance specifications such as a wide angle of view and a high zoom ratio of as high as 5, is extremely small in depth and ensures that the optical path of the optical system can easily be bent by a reflecting optical element. A zoom lens includes a first lens group G1 with a positive power, a second lens group G2 with a negative power, a third lens group G3 with a positive power, a fourth lens group G4 with a positive power, a fifth lens group G5 with a negative power, and a sixth lens group G6 with a positive power, wherein upon zooming from a wide-angle end to telephoto end, the first lens group G1 remains fixed relative to an image surface I and at least second and fourth lens groups G2 and G4 move, the first lens group G1 includes, in order from the object side, a negative lens, a reflecting optical element P for bending an optical path, and a positive lens, and conditional expression (1) is satisfied.

Abstract: An optical path passing through an object-side lens group is bent at a right angle by an optical device so as to be a vertical optical path. A lens group on imaging surface side for forming an image on an imaging surface is disposed on the vertical optical path. The lens group on imaging surface side moves along the vertical optical path, and has a plurality of movable lens groups at least for zooming. The cam plate moves in a direction perpendicular to the vertical optical path within a plane perpendicular to an optical axis of the object-side lens group and not protruding toward an object side compared with the object-side lens group. A plurality of cam slots are formed on the cam plate. The cam slots are fit to a part of the plurality of movable lens groups. In accordance with the movement of the cam plate, the cam slots move the plurality of the movable lens groups such that zooming and focusing are performed.

Abstract: A rear-focusing type zoom lens includes, in order from an object side, a positive first group being fixed, a negative second group moving toward an image plane along an optical axis during zooming from a wide-angle end to a telephoto end; a negative third group being fixed in an optical axis direction, and a positive fourth group moving along the optical axis direction to correct image plane variation being caused by zooming. The first group includes a first subgroup having a negative power as a whole and a second subgroup having a positive power as a whole. The first subgroup includes a negative meniscus lens having a convex surface directed toward the object side and a negative lens. The second subgroup includes a positive lens group having at least one positive lens, a negative lens, a positive lens, and another positive lens group having at least one positive lens.

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: Providing a high optical performance zoom lens system with realizing a high zoom ratio and compactness suitable for a highly integrated electronic imaging device. The system includes, in order from an object along an optical axis: a first group G1 having positive refractive power; a second group G2 having negative refractive power; a third group G3 having positive refractive power; a fourth group G4 having positive refractive power; and a fifth group G5 having negative refractive power. Upon zooming from a wide-angle end state W to a telephoto end state T, the second group G2 and the fourth group G4 are moved along the optical axis. The first group G1 includes, in order from the object along the optical axis, a front group G1f having negative refractive power, an optical-path-bending element P for bending an optical path, and a rear group G1r having positive refractive power. Given expression is satisfied.

Abstract: A zoom lens includes a focus unit, a zoom unit, an aperture stop, and an imaging unit having a splitting element that are arranged in that order from an object side to an image side. The splitting element includes an incident surface for a light beam, a half mirror surface for splitting the light beam into reflected light and transmitted light, a splitting exit surface from which the reflected light is emitted, and an exit surface from which the transmitted light is emitted. The incident surface and the exit surface are perpendicular to an optical axis of the zoom lens. The ratio of the distance from the aperture stop to the exit surface and the equivalent air length from the aperture stop to an image plane of the zoom lens and the ratio of the effective diameters of the exit surface and the splitting exit surface are set properly.

Abstract: A zoom lens system includes, in order from an object side to an image side, a first positive lens group (G1), a second negative lens group (G2), a third positive lens group (G3), and a fourth positive lens group (G4). The second and third lens groups are movable for varying the focal length. The zoom lens system offers a four-times zoom ratio, and employs two plastic aspheric lenses (L3, L9) and a resin hybrid lens (L6). The first lens group consists of two lenses (L1, L2) arranged in an abutting relationship. The second and third lens groups each includes a pair of cemented lenses (L4, L5; L7, L8).

Abstract: A zoom lens formed of a plurality of lens groups and performing zooming by changing separations between predetermined lens groups. A lens group closest to an object side is fixed in both optical axis directions during zooming, and has a reflecting member for folding an optical axis approximately 90 degrees. A final lens group positioned closest to an image side and fixed in both optical axis directions during zooming has a lens part group SG having positive refractive power and a lens part group RG arranged adjacent to the image side of the lens part group SG and having negative refractive power. A blur is corrected by shifting the lens part group SG in either direction perpendicular to the optical axis.

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, 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: An illumination unit includes multiple light source units to emit light having different wavelengths, and a synthesizing prism to synthesize the emitted light. The synthesizing prism includes a first triangular prism (tp) having a first outer surface (os) to transmit (reflect) the light according to the light's input a direction, and first and second boundary surfaces (bs), a second tp having a second os to transmit the light, a third bs facing the second bs, and a fourth bs, a third tp having a third os to transmit (reflect) the light according the light's input direction, a fifth bs facing the fourth bs, and a sixth bs facing the first bs, and a color separation portion arranged at least one of positions between the second and third bs, the fourth and fifth bs, and the sixth and first bs, to selectively transmit (reflect) the light according to wavelengths thereof.

Abstract: 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, and a fourth lens group having a positive refractive power, which are disposed in order from an object along the optical axis, wherein the third lens group comprises: a pre-group, which has a first positive lens, a negative meniscus lens having a convex surface facing the object, a second positive lens, and which has a positive refractive power; and a negative meniscus lens having a convex surface facing the object, which are disposed in order from the object; at least one of three surfaces of an object side and image side lens surfaces of the first positive lens and an object side lens surface of the negative meniscus lens is aspherical; and at least one of three surfaces of an object side lens surface of the second positive lens, and an object side and image side lens surfaces of the negative meniscus lens is aspherical.

Abstract: A reduction optical system for forming, without re-imaging, a reduced image of a subject image formed by a main lens system. The reduction optical system has on the most object side a meniscus single-lens element convex to the object side, allowing for a high-performance, and compact reduction optical system by permitting lens replacement of the main lens system.

Abstract: An object is to provide an ultra-compact zoom lens system suitable for a video camera and a electronic still camera using a solid-state imaging device and the like with securing high optical performance. The zoom lens system includes, in order from an object along the optical axis, a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having positive refractive power, and at least one lens group having positive refractive power. The first lens group is fixed upon zooming from a wide-angle end state to an telephoto end state and focusing. A plurality of lens groups except the first lens group are moved upon zooming from the wide-angle end state to the telephoto end state, respectively. A plurality of lens groups except the first lens group G1 are moved upon focusing, respectively. Given conditional expressions are satisfied.

Abstract: An electrode for an extra-high pressure discharge lamp, comprises large diameter portion which is symmetrical with respect to an axis of the electrode, a small diameter portion connected to the large diameter portion, wherein the large diameter portion is connected to the small diameter portion through an outer surface portion of the electrode, wherein a stripe lines like pattern portion, extending along an electrode axis direction, is formed on a portion to be brought in contact with glass of a lamp, and wherein unevenness is formed over an entire circumference of the electrode in a cross sectional view of the electrode taken along a direction perpendicular to the electrode axis direction.