Abstract: A digital camera and a mobile information terminal apparatus including a lens barrel including a first lens group and a second lens group disposed on an optical axis and configured to be related to operations concerned with changing overall relative magnification, a third lens group disposed on the optical axis and configured to be related to operations concerned with changing overall relative magnification and to be retracted from the optical axis in a collapsed state, a first driving device configured to drive the first lens group and the second lens group, a second driving device configured to drive the third lens group, a CCD disposed on the optical axis and configured to photograph a subject, a distance determining device configured to determine a distance to the subject, and a floating control device configured to drive at least one of the first driving device and the second driving device based on distance information obtained from the distance determining device to change an interval between the first

Abstract: An image pickup apparatus includes a zoom lens including at least two movable lens groups; an image pickup element that converts an optical image formed with the zoom lens into an electric signal; and an image processor that electrically corrects a lateral chromatic aberration to be generated at the zoom lens. The zoom lens satisfies Conditional Expressions (1) and (2) as follows, ?5.0<W_ate(X)/T_ate(X)<?0.2??(1) 0.003<|Max_ate(10)/Himg |<0.03??(2) where W_ate(X) is an aberration amount of the lateral chromatic aberration from the C-line to the g-line, at a wide-angle end, corresponding to a (X×10) % image height, T_ate(X) is an aberration amount of the lateral chromatic aberration from the C-line to the g-line, at a telephoto end, corresponding to a (X×10) % image height, Max_ate(X) is one of W_ate(10) and T_ate(10), the one having a larger absolute value, and Himg is a diagonal length of the image pickup element.

Abstract: A lens unit according to the present invention is capable of varying power for forming an image onto an image pickup element. The lens unit includes: a plurality of lens groups, a diaphragm, and a shutter. In the plurality of lens groups, a distance between a k-th lens group counting from an object side and a (k+1)-th lens group arranged at an image side of the k-th lens group changes for varying power. The diaphragm is arranged between a position at an image side of the k-th lens group and a lens surface facing the object side of a lens closest to the image in the (k+1)-th lens group. The shutter is provided with an aperture in a noncircular shape and fulfills the predetermined conditional formulas.

Abstract: A zoom lens system comprising, in order from an object side: a first lens unit comprising two lens components; and a second lens unit comprising one lens component, during zooming, a space between the first lens unit and the second lens unit changing, the first lens unit and the second lens unit having aspherical surfaces, at least one aspherical surface of the first lens unit satisfying the following condition: R1/h1<1.35, wherein R1 denotes a paraxial radius of curvature of the at least one aspherical surface, and h1 denotes a length from a first intersection between a chief ray reaching a point of maximum image height on an image surface and the at least one aspherical surface to an optical axis in the wide-angle end at a time when the chief ray enters the zoom lens system with an angle of incidence equal to or larger than 36 degrees and passes through the at least one aspherical surface.

Abstract: A five-element 3:1 zoom lens system in which the first lens group has a negative power and includes two lens elements and the second lens group has a positive power and includes a pair of lens sub-groups, the first sub-group having a positive power and including a pair of lens elements and the second sub-group having a positive power and including a single lens element. In one embodiment the second sub-group remains stationary relative to the location of the image plane and in another embodiment the second sub-group remains stationary relative to the first sub-group while they are moved relative to the location of the image plane. Several of the lens element surfaces are aspherical. The second lens element of the first sub-group is relatively thick and has a relatively high optical power. The overall length of the lens system is relatively short.

Abstract: An imaging lens including, in order from an object side towards an image surface side, a diaphragm, a first lens which is a meniscus lens having a positive power whose convex surface faces the object side, and a second lens which is a lens having a positive power whose convex surface faces the image surface side, wherein conditions expressed by each of following expressions (1)-(6) are to be satisfied; 1.25?L/fl?0.8, 0.55?f1/f2>0, 1.5?f1/fl?0.9, 1?d2/d1?0.2, 0.35?d1/fl?0.1, and 0.27?d3/fl?0.1 (where, L: entire length of the imaging lens, fl: focal distance of the entire imaging lens, f1: focal distance of the first lens, f2: focal distance of the second lens, d1: center thickness of the first lens, d2: space between the first lens and the second lens on the optical axis, and d3: center thickness of the second lens).

Abstract: A zoom lens includes a first lens group with a negative refractive power and a second lens group with a positive refractive power, wherein the second lens group is disposed between the first lens group and an image side, and the first lens group and the second lens group are suitable for moving between an object side and the image side. In addition, the first lens group includes a first lens with a negative refractive power, and the first lens is a meniscus lens with a convex surface facing the object side and has an Abbe number greater than 50. A focal length of the zoom lens is F, a focal length of the first lens group is F1, a curvature radius of a surface facing the second lens group of the first lens is R2, and ?0.6<F/F1<?0.2, 0.7<R2/F<1.8.

Abstract: An image forming optical system comprising: a first positive lens unit disposed closest to the object side in the image forming optical system; an aperture stop; and a second positive lens unit disposed closest to an image side in the image forming optical system, the second lens unit comprising: a front lens unit whose surface closest to the image side is a concave surface which faces the image side; and a rear lens unit consisting of one positive meniscus lens whose convex surface faces the image side, the image forming optical system satisfying the following conditions: ?1.0<R2/R3<?0.01; and??(1) 0.3<?D2G/FL<1.2.

Abstract: The two-group zoom lens comprises in order from the object side, the first negative lens group, and the second positive lens group. Change of magnification from a wide angle end to a telephoto end is performed by narrowing the interval between two lens groups, and the first negative lens group is moved toward the object side when focusing from focusing at the infinite object point to focusing at a short-distance object point performed, and specific conditions are satisfied.

Abstract: In a thin projector for projecting an image from a light valve such as a DMD, a compact zoom lens comprises, in order, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens-group having a negative refractive power, and a fourth lens group having a positive refractive power. The fourth lens group is fixed while the focal length is being changed. The first and second lens group are movable on an optical axis in a direction from the enlarging side towards the reducing side over a range from a wide angle end to an intermediate range, and are movable on the optical axis in a direction from the reducing side towards the enlarging side over a range from the intermediate range to a telephoto end. The third lens group moves on the optical axis in a direction from the reducing side to the enlarging side over a range from the wide angle end to the telephoto end, whereby the focal length of the whole lens system of the zoom lens is changed.

Abstract: Providing a zoom lens system excellently correcting various aberrations with accomplishing to be compact, lightweight, and slim upon being accommodated, and to provide an optical apparatus using the zoom lens system. The system consists of, in order from an object, a first group G1 having negative power, a second group G2 having positive power. Upon zooming from a wide-angle end W to a telephoto end T, a distance between the first group G1 and the second group G2 decreases. The first group G1 consists of, in order from the object, a first lens L1 having negative power and a second lens L2 having positive power. The second group G2 consists of, in order from the object, a third lens L3 having positive power, a fourth lens L4 having negative power, and a fifth lens L5 having positive power. Given conditions are satisfied.

Abstract: A zoom lens includes a first and a second lens group respectively having negative and positive refractive power, and changes a focal length by changing a distance between the first and the second lens group. The second lens group includes a first lens having positive refractive power and a convex surface, a second lens having positive refractive power, an aspheric surface, and a convex surface, a third lens having negative refractive power, a fourth lens having positive refractive power, and a fifth lens including one lens or more having positive refractive power. The third and the fourth lenses are connected, and the zoom lens satisfies Nd21>1.8 and ?d24>80, where Nd21 is a refractive index of the first lens of the second lens group at a d-line, and ?d24 is an Abbe number of the fourth lens of the second lens group at a d-line.

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: The invention relates to an optical system that is capable of providing a zoom lens having improved image-formation capability with a reduced number of lenses, and fabricating a slim yet high-performance digital or video camera. The optical system comprises a cemented lens having a cementing surface on its optical axis. Air contact surfaces on the light ray entrance and exit sides of the cemented lens G2 are aspheric, and at least one cementing surface in the cemented lens G2 satisfies condition (1). 6.4<|(r/R)| ??(1) Here r is the axial radius of curvature of the cementing surface, and R is the maximum diameter of the cementing surface.

Abstract: The invention relates to an imaging system in which, while high image quality is maintained with the influence of diffraction minimized, the quantity of light is controlled, and which enables the length of the zoom lens to be cut down. The imaging system comprises a zoom lens comprising a plurality of lens groups G1 and G2 wherein the spacing between individual lens groups is varied to vary a focal length and an aperture stop located in an optical path for limiting at least an axial light beam diameter, and an electronic image pickup device I located on the image side of the zoom lens. The aperture stop has a fixed shape, and a filter S2 for performing light quantity control by varying transmittance is located on an optical axis of a space located at a position different from that of a space in which the aperture stop is located.

Abstract: The invention relates to a zoom lens with an easily bendable optical path, which has high optical specification performance such as a high zoom ratio, a wide-angle arrangement, a small F-number and reduced aberrations. The zoom lens comprises a first lens group G1 that remains fixed during zooming, a second lens group G2 that has negative refracting power and moves during zooming, a third lens group G3 that has positive refracting power and moves during zooming, and a fourth lens group G4 that has positive refracting power and moves during zooming and focusing. The first lens group comprises, in order from an object side thereof, a negative meniscus lens component convex on an object side thereof, a reflecting optical element for bending an optical path and a positive lens. Upon focusing on an infinite object point, the fourth lens group G4 moves in a locus opposite to that of movement of the third lens group G3 during zooming.

Abstract: The present invention is directed to a zoom lens used for image pick-up optical system of digital still camera, or video camera, and is composed, in order from the object side, of a first group GR1 including a reflection member for bending or folding the optical axis and having negative refractive power, a second group GR2 having negative refractive power, a third group GR3 having positive refractive power, and a fourth group GR4 having positive refractive power, wherein a light quantity adjustment member ST1 for adjusting light quantity is fixed during zooming operation.

Abstract: The invention relates to an optical system that is capable of providing a zoom lens having improved image-formation capability with a reduced number of lenses, and fabricating a slim yet high-performance digital or video camera. The optical system comprises a cemented lens having a cementing surface on its optical axis. Air contact surfaces on the light ray entrance and exit sides of the cemented lens G2 are aspheric, and at least one cementing surface in the cemented lens G2 satisfies condition (1). 6.4<|(r/R)| ??(1) Here r is the axial radius of curvature of the cementing surface, and R is the maximum diameter of the cementing surface.

Abstract: A zoom lens includes a first lens group with a negative refractive power and a second lens group with a positive refractive power. The first lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence and refractive powers thereof are negative, negative, negative and positive respectively. The first and second lenses are meniscus lenses and two surfaces of the second lens are aspheric surfaces. The third lens is a biconcave lens and the fourth lens is a biconvex lens. The second lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence and refractive powers thereof are positive, positive, positive, negative and positive respectively. A cemented doublet lens is composed of the seventh and eighth lenses. The ninth lens is a biconvex lens.

Abstract: A zoom lens system comprising, in order from an object side: a first lens unit comprising two lens components; and a second lens unit comprising one lens component, during zooming, a space between the first lens unit and the second lens unit changing, the first lens unit and the second lens unit having aspherical surfaces, at least one aspherical surface of the first lens unit satisfying the following condition: R1/hl 1.35, wherein R1 denotes a paraxial radius of curvature of the at least one aspherical surface, and hi denotes a length from a first intersection between a chief ray reaching a point of maximum image height on an image surface and the at least one aspherical surface to an optical axis in the wide-angle end at a time when the chief ray enters the zoom lens system with an angle of incidence equal to or larger than 36 degrees.

Abstract: A zoom lens system that has two lens groups with respectively negative and positive refractive powers in that order from a display medium, such as a screen, side is provided. The first lens group and the second lens group respectively include at least one aspherical surface. An air distance dw between the first lens group and the second lens group at the wide angle end, an air distance dt between the first lens group and the second lens group at the telephoto end, a combined focal length f1 of the first lens group, a combined focal length f2 of the second lens group, and the combined focal length fw of the zoom lens system at the wide angle end satisfy the following conditions: 0.05<dt/dw<0.1; dt<2.5 mm; 1.3<|f1/fw|<1.6; 1.1<|f2/f1|<1.4.

Abstract: A zoom lens system includes a first lens unit having a negative optical power and a second lens unit having a positive optical power in order from the object side to the image side. In a zooming operation, the distance between the first lens unit and the second lens unit at the telephoto end is smaller than that at the wide angle end. The first lens unit includes a single negative lens element and a single positive lens element, and materials of the lens elements are adequately set.

Abstract: A zoom lens, in order from an object side, includes a first lens group having a negative refracting power, a second lens group having a positive refracting power and an aperture stop. When zooming from a wide-angle end to a telephoto end, at least the first lens group and the second lens group move, so that an interval between the first lens group and the second lens group can become small and an interval between the second lens group and an image plane can become large. The second lens group has at least three positive lenses and two negative lenses and at least one of the three positive lenses is an aspheric positive lens and an Abbe's number of the glass type: ?d and an anomalous dispersion of the glass type: ??g,F satisfy conditions: ?d>80.0 ??(1) ??g,F>0.

Abstract: At least one exemplary embodiment is directed to a zoom lens system which includes a first lens unit having negative refractive power and a second lens unit having positive refractive power. The first and second lens units are provided in order from the object to image sides. The distance between the first and second lens units change during zooming. The first lens unit includes a compound optical element including a lens element and a resin layer having optical performance different from that of the lens element and being stacked on the lens element. The zoom lens system can satisfy: 20<|?dg??dj| and fg/fj<0, where fg and ?dg represent the focal length and the Abbe number of the lens element and fj and ?dj represent the focal length and the Abbe number of the resin layer.

Abstract: A zoom lens is disclosed. The zoom lens comprises a first lens group located adjacent to an object side and having a negative refractive power, and a second lens group located adjacent to an image side and having a positive refractive power, wherein zooming is made as an interval between the first lens group and the second lens group is varied.

Abstract: An object of the present invention is to provide a compact size variable power optical system capable of producing a high quality image. The variable power optical system comprises a plurality of lens groups for forming an optical image on an image surface of an image pickup device. Among the plurality of lens groups, the first lens group, which is disposed in the most subject side has a negative refraction power, includes at least a lens having a negative refraction power and a reflective optical element for bending the optical axis. When varying the variable power, the axial distance between the first lens group and the image surface varies. When Nd denotes the refraction power of the lens having negative refraction power at d-line, the refraction power satisfies the conditional formula Nd>1.81.

Abstract: A zoom lens includes a first lens group with a negative refractive power and a second lens group with a positive refractive power. The first lens group includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence and refractive powers thereof are negative, negative, negative and positive respectively. The first and second lenses are meniscus lenses and two surfaces of the second lens are aspheric surfaces. The third lens is a biconcave lens and the fourth lens is a biconvex lens. The second lens group includes a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens arranged in sequence and refractive powers thereof are positive, positive, positive, negative and positive respectively. A cemented doublet lens is composed of the seventh and eighth lenses. The ninth lens is a biconvex lens.

Abstract: A zoom lens system excellently correcting various aberrations with accomplishing compactness, lightweight, and slimness upon accommodating lens barrel. The system consists of, in order from an object, a first group G1 having negative power, and a second group G2 having positive power. Upon zooming from a wide-angle end to a telephoto end, a distance between the first group G1 and the second group G2 decreases. The first group G1 consists of, in order from the object, a first lens L1 with negative power, and a second lens L2 with positive power. The second group G2 consists of three lenses that are, in order from the object, a third lens L3 with positive power, a fourth lens L4 with negative power having a convex surface facing the object, a fifth lens L5 with positive power. The three lenses are disposed without cemented each other. Given condition is satisfied.

Abstract: The zoom lens includes a first lens group G1 having a negative refracting power, an aperture stop FA, a second lens group G2 having a positive refracting power, and a third lens group G3 having a positive refracting power, which are disposed in order from an object side. In this configuration, at least the first lens group G1 and the second lens group G2 move along with changing magnification from the wide-angle end toward the telephoto end, in a manner that a spacing between the first lens group G1 and the second lens group G2 decreases gradually and a spacing between the second lens group G2 and the third lens group G3 increases gradually. Here, the second lens group G2 includes a first cemented lens C1 having at least three pieces of lenses united, and a second cemented lens C2 having at least two pieces of lenses united.

Abstract: Providing a high zoom ratio zoom lens system having a short total lens length and a small diameter of the first group despite of securing excellent optical performance, a half angle of view of 3.5° or less in the telephoto end, an f-number of 6 or less in the telephoto end, and a zoom ratio of about 10 or more. The system is composed of a first group having positive power, a second group having negative power, a third group having positive power, and a fourth group having positive power. The first group is composed of, in order from the object, a negative meniscus lens having a convex surface facing the object, a first positive lens having a convex surface facing the object, and a second positive lens. All groups moves along the optical axis upon zooming from a wide-angle end to a telephoto end. Given conditions are satisfied.

Abstract: A zoom lens includes a first lens group with a negative refractive power and a second lens group with a positive refractive power, wherein the second lens group is disposed between the first lens group and an image side, and the first lens group and the second lens group are suitable for moving between an object side and the image side. In addition, the first lens group includes a first lens with a negative refractive power, and the first lens is a meniscus lens with a convex surface facing the object side and has an Abbe number greater than 50. A focal length of the zoom lens is F, a focal length of the first lens group is F1, a curvature radius of a surface facing the second lens group of the first lens is R2, and ?0.6<F/F1<?0.2, 0.7<R2/F<1.8.

Abstract: A zoom lens includes, in sequence from the object side: a first lens group with an overall negative refractive power; and a second lens group with an overall positive refractive power. A zoom factor changes by moving the second lens group. Focal adjustments are made by moving the first lens group accompanied by the change of the zoom factor made by the movement of the second lens group. The first lens group includes a first lens having a negative refractive power and a second lens having a positive refractive power. The second lens group includes a third lens having a positive refractive power, a fourth lens with a positive refractive power and a fifth lens with a negative refractive power bonded together, and a sixth lens with a positive refractive power. The bonded lenses form a meniscus shape with a convex surface facing the object side. The resulting lens is short in length, compact, thin, and suitable for digital still cameras.

Abstract: Providing a two-lens-group zoom lens system that has a wide angle of view, a fast aperture ratio with an f-number of about 2.8, a high zoom ratio, and high optical performance, and is easy to be manufactured. The zoom lens system is composed of, in order from an object, a first lens group G1 having negative refractive power, and a second lens group G2 having positive refractive power. Zooming is carried out by varying a distance between the first lens group G1 and the second lens group G2. The second lens group G2 includes, in order from the object, a first positive lens component L1, an aperture stop S, a second positive lens component L2, and a negative lens L3. Given conditional expression is satisfied.

Abstract: A device for focusing a laser beam includes a first telescopic configuration and a second telescopic configuration. The first telescopic configuration includes a collimating optical element for collimating the laser beam and a downstream focusing optical element for focusing the laser beam onto a focal point. The second telescopic configuration includes a first lens and a downstream second lens disposed in the divergent beam path upstream of the first telescopic configuration. The first and second lenses of the second telescopic configuration are moveable relative to each other in the beam direction.

Abstract: An electronic imaging apparatus includes a zoom optical system having, in order from the object side, a first lens unit with negative power and a second lens unit with positive power, in which lens components having refracting power in the first lens unit are only a single biconcave negative lens element located at the most object-side position and a positive lens component located at the most image-side position; an electronic image sensor placed on the image side of the zoom optical system; and an image processing section electrically processing image data obtained by the electronic image sensor to change the shape thereof. The zoom lens system satisfies the following conditions in focusing of a nearly infinite object point: 0.85<|y07/(fw·tan ?07w)|<0.97 0.75<|y10/(fw·tan ?10w)|<0.

Abstract: A first group 10 having a negative refractive power, a diaphragm St and a second group 20 having a positive refractive power are arranged in order from the object side. Power variation from the wide angle end to the telephoto end is executed by moving the second group 20 to the object side along an optical axis. Correction of an image plane associated with the power variation is made by moving the first group 10 along the optical axis. The second group 20 includes a first lens L21 having at least one aspheric surface and having a positive refractive power; a cemented lens formed of a second lens L22 having a positive refractive power and a third lens L23 having a negative refractive power; a fourth lens L24 having a negative refractive power; and a fifth lens L25 having a positive refractive power in order from the object side.

Abstract: A zoom lens including front and rear elements, the front elements is set up so that the front elements are disposed at a position to satisfy the formula: T 1 ? Ha 1 + HH 1 + L + HH 2 + f 2 ? ( f 1 - L ) f 1 + f 2 - L + f 1 2 m - f 1 , where a length from the top of the front elements on the optical axis to the front main point of the front elements: Ha1, a main point of the front elements: HH1, a length from the rear main point of the front elements to the front main point of the rear elements: L, a main point of the rear elements: HH2, a focal length of the front elements: f1, a focal length of the rear elements: f2, a length from the object at the time of photography to the front main point of the front elements: m, and a length from the top of the front elements on the optical axis to the imaging plane: T1.

Abstract: To provide a compact, high-performance zoom lens having a small lens aperture for enlarging an image from a light bulb such as a DMD for forming an image by changing a reflecting direction of light and projecting the image so enlarged on to a screen or the like, and the zoom lens includes, in order from a magnifying side, a first lens group having a negative refractive power as a whole and a second lens group having a positive refractive power as a whole, wherein changing the magnification of a whole lens system thereof is attained by configuring such that while a magnification varying operation is in effect, the first lens group and the second lens group are made to move on the optical axis.

Abstract: A zoom lens is equipped with: a first lens group having an overall negative refractive power and a second lens group having an overall positive refractive power in sequence from the object side to the image plane side. Zoom magnification is changed from a wide-angle end to a telephoto end by moving the first lens group to the image plane side and then reversing the motion to the object side while the second lens group is moved to the object side. The condition (1) 0.90<=(DG1+DG2)/fw<=2.30 and the condition (2) 0.5<=|fG1|/fG2<=1.6 are met, where DG1 is the thickness of the first lens group; DG2 is the thickness of the second lens group; fw is the focal length of the lens system at the wide-angle and; fG1 is the focal length of the first lens group; and fG2 is the focal length of the second lens group.

Abstract: At least one exemplary embodiment is directed to a zoom lens, which includes, in order from an object side to an image side, a first lens unit of negative refractive power, and a second lens unit of positive refractive power. An interval between the first and second lens units changes during zooming. The first lens unit includes a negative lens and a positive lens in order from the object side to the image side. A refractive index of a material of the negative lens, a refractive index of a material of the positive lens, a focal length of the first lens unit satisfy appropriate conditions.

Abstract: The invention makes a suitable selection from zoom modes and lens elements so thin that the thickness of each lens group can reduced, thereby slimming down a zoom lens with great thoroughness and, hence, an electronic image pickup system. The electronic image pickup system a zoom lens and an electronic image pickup device located on the image plane side of the zoom lens. The zoom lens comprises, in order from the object side, a first lens group G1 comprising two lens components and having generally negative power and a second lens group G2 comprising two lens components and having generally positive power. The focal length of the zoom lens can be varied by varying the air separation between the first lens group G1 and the second lens group G2. The zoom lens should satisfy at least one of conditions (a) to (n).

Abstract: A zoom lens includes, in order from the object side, the first lens unit consisting of one negative lens component in which a plurality of lens components are cemented to one another and the second lens unit including one negative lens component and having positive refracting power as a whole. In this case, the zoom lens satisfies the following condition: 0.15<t1/fw<0.6 where t1 is the thickness, measured along the optical axis, of the first lens unit and fw is the focal length of the entire system at the wide-angle position of the zoom lens.

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

Abstract: An object is to provide a zoom lens system having compactness of about a normal lens, small number of lens elements, a zoom ratio about 2.9, good productivity, and high optical performance. The system includes, in order from the object, a first lens group with negative power and a second lens group with positive power. Zooming is performed by varying a distance between the first lens group and the second lens group. The first lens group includes at least a negative lens and a positive lens. The second lens group includes a front lens group with positive power and a rear lens group with positive power. The front lens group includes a positive lens and a cemented lens constructed by a positive lens cemented with a negative lens. The rear lens group includes a cemented lens constructed by a negative lens cemented with a positive lens. Given conditions are satisfied.

Abstract: A small high-definition variable power optical system having a variable power ratio of about two to three times; an imaging apparatus including the variable power optical system; and digital equipment mounted with the imaging apparatus are provided. The variable power optical system, consisting of a plurality of lens groups, for performing variable power by changing the distance between each lens groups in an optical axis direction is configured by two or more lens groups, each having negative or positive optical power, arranged in such order from the object side. The first lens group is a cemented lens configured by at least one negative lens and at least one positive lens arranged in order from the object side. At least one aspherical surface is arranged to each of the first lens group and the second lens group. A third lens group having a positive optical power is arranged on the image plane side of the second lens group.

Abstract: At least one exemplary embodiment is directed to a zoom lens including a plurality of lens units, in which an interval between respective adjacent lens units varies during zooming, an aperture stop, and a refractive optical element made of a solid material having an Abbe number (?d) and a relative partial dispersion (?gF) satisfying the following condition: ?gF?(?1.665×10?7·?d3+5.213×10?5·?d2?5.656×10?3·?d+0.755)>0. The refractive optical element is located at a position in which distances (dw, dt) from the aperture stop to the refractive optical element on an optical axis at a wide-angle end and a telephoto end, respectively, satisfy the following condition: dt/dw>1.1.

Abstract: A zoom lens system includes a negative first lens group, a variable diaphragm, a positive second lens group, in this order from the object. Zooming is performed by moving the negative first lens group and the positive second lens group. The negative first lens group is constituted by at least two negative lens elements and at least two positive lens elements. The zoom lens system satisfies the following conditions: 1.5<|f1/fw|<1.8??(1) 1.0<|f2/(fw×ft)1/2<1.3??(2) 1.0<|f2/f1|<1.2??(3) wherein f1 designates the focal length of the negative first lens group; f2 designates the focal length of the positive second lens group; fw designates the focal length of the entire the zoom lens system at the short focal length extremity; and ft designates the focal length of the entire the zoom lens system at the long focal length extremity.

Abstract: A two-unit zoom lens system which comprises a negative first lens unit G1 and a positive second lens unit G2, during change of magnification from a wide-angle end to a telephoto end, the first lens unit and the second lens unit are moved so as to reduce a space between the first lens unit and the second lens unit, the first lens unit includes a negative sub-unit G1a and a positive sub-unit G1b, the second lens unit has a first positive lens L21, a second negative lens L22, and a third positive lens L23, and the system further has an aperture stop S disposed in an air space which comes into contact with the first positive lens L21.

Abstract: A projection lens for use with LCD panels is provided. The lens has a first lens unit which includes a strong negative lens element having an aspherical surface which provides distortion correction, and a second lens unit which includes a first lens subunit separated by an airspace from a second lens subunit, wherein the first lens subunit has a strong positive power and the second lens subunit has a weaker power. The second lens subunit can include a negative lens element, followed by a positive lens element, followed by a plastic lens element having an aspherical surface. The projection lens has a field of view of at least 35° so that the overall projection lens system has a compact size.