Abstract: A microscope objective lens is disclosed that includes, in order from the object side, a first lens group having positive refractive power, a second lens group having positive refractive power that is movable along the optical axis, and a third lens group. The first lens group includes, in order from the object side, two meniscus lens components, each with its concave surface on the object side, and at least one positive lens component, and the third lens group has adjacent concave lens element surfaces that face each other and are in contact with air. Specified conditions may be satisfied, and one or more lens components in the first lens group and the second lens group may be movable.

Abstract: An imaging optical system, which is designed in a small size with low manufacturing costs, aberrations such as chromatic aberration of the imaging optical system being appropriately corrected, is provided. The imaging optical system comprises a first lens having positive power, a second lens having positive power and a third lens having negative power with an aspherical surface in the image side, the aspherical surface being shaped in a concave shape facing toward an image side in a vicinity of the optical axis and shaped in a convex shape facing toward the image side in a surrounding of the optical axis. The imaging optical system is designed to satisfy a formula, ?3??2>10, where ?3 denotes an Abbe number of the third lens and ?2 denotes an Abbe number of the second lens.

Abstract: An imaging lens has a compact shape and sufficiently compensates for various aberrations. The imaging lens includes a first lens, a second lens, and a third lens disposed sequentially, with the first lens toward an object. The conditions “0.5H<T0<0.7H,” “2<?r4/?<2.5,” and “0.15<?r5/?<0.3” are satisfied, where: H is the effective radius of the surface of the third lens facing an image surface; T0 is the distance between the optical axis and a point on a line parallel to the optical axis and normal to the surface of the third lens facing the image surface; ? is the combined refractive power of the imaging lens; ?r4 is the refractive power of the surface of the second lens facing the image surface; and ?r5 is the refractive power of the surface of the third lens facing the object.

Abstract: A lens system includes a positive refractive power first lens, a positive refractive power second lens, and a negative refractive power third lens in that order from the object side of the lens system. Wherein the lens system satisfies the following conditions: (1) 0.25<R1F/F<0.5; (2) R2F<R2R<0; and (3) 0<R1F<R1R, wherein, R1R and R1F are radius of curvature of object side surface and image side surface of the first lens respectively, R2R and R2F are radius of curvature of object side surface and image side surface of the second lens respectively, and F is a focal length of the lens system.

Abstract: An imaging lens including, in order from an object side to an image surface side on an optical axis, a first lens that is a meniscus lens having a positive power whose convex surface faces the object side, a diaphragm, a second lens that is a meniscus lens having a positive power whose convex surface faces the image surface side, and a third lens that is a biconcave lens having a negative power, wherein conditions expressed by 0.023?d4/fl?0.11 and 0.068<f1/f2?0.8 (where, d4: distance between the second lens and the third lens on the optical axis, f1: focal distance of the entire lens system, f1: focal distance of the first lens, and f2: focal distance of the second lens) are to be satisfied.

Abstract: An imaging lens system, in order from the object side to the image side thereof, includes a first lens with positive refractive power, a second lens with positive refractive power, a third lens with negative refractive power and an image sensing element. The imaging lens system satisfies the following formulas: L/TTL>1.23, and 0.3<G1R1/F1<0.4, where an active surface of the image sensing element is square and only includes effective pixels, and L is the length of one side of the active surface, image sensing element TTL is the distance along an optical axis thereof from the object-side lens surface of the first lens to an imaging plane of the image side, G1R1 is the radius of curvature of the object-side lens surface of the first lens, and F1 is the focal length of the first lens.

Abstract: An image pick-up lens for forming an image of an object on a solid image pick-up element having a rectangular effective pixel area, has a first lens; a second lens; a third lens; and a diaphragm having an aperture. The following conditional expressions are satisfied: 15°<IAD<35° |IAh?(IAD·Yh/YD)|<5° where, YD: a length of ½ of the diagonal length of the rectangular effective pixel area of the solid image pick-up element, Yh: an arbitrary image height of the image pick-up lens (where, Yh<YD), IAD: an angle formed between a chief ray of a light flux forming an image at the image height YD of the image pick-up lens and the optical axis, and IAh: an angle formed between a chief ray of a light flux image forming an image at the image height Yh of the image pick-up lens, and the optical axis.

Abstract: An imaging lens module includes a fixed diaphragm and an optical module. The optical module includes first, second and third lenses arranged from an object side to an image side in a sequence of: the first lens component of positive refractive power with a meniscus shape, having a convex surface on the object side and at least one aspheric surface; the diaphragm; the second lens component of positive refractive power with a meniscus shape, having a concave surface on the object side and at least one aspheric surface; the third lens component of negative refractive power with two aspheric surfaces, having a concave surface with smaller curvature on the object side, a wavy surface on the image side, and a concave surface on the image side near the optical axis. The imaging lens module is a lens module with the features of high imaging quality, miniaturization, high brightness and high yield rate.

Abstract: It is to provide an imaging lens that can maintain optical performance and actualize size and weight reduction. The imaging lens comprises, in order from an object side to an image surface side, a first lens that is a meniscus lens having a positive power whose convex surface faces the object side, a diaphragm, a second lens that is a meniscus lens having a positive power whose convex surface faces the image surface side, and a third lens that is a biconcave lens having a negative power, wherein a condition expressed by 0.11<d4/fl?0.25 (where, d4: distance between the second lens and the third lens on the optical axis, and fl: focal distance of the entire lens system) is to be satisfied.

Abstract: An imaging lens includes, in order from an object side, a first lens with a positive refractive power having a biconvex shape; an aperture stop having a predetermined aperture diameter; a second lens with a positive refractive power having a concave surface on the object side, at least one of the object-side surface and an image-plane-side surface of the second lens being aspherical; and a third lens with a negative refractive power having a concave surface on the object side and an aspherical surface with an inflection point in an effective-diameter area on the image-plane side, whereby aberrations can be effectively corrected, the total length of the lens system can be reduced to reduce the overall size, in particular the thickness, and a shutter can be readily accommodated.

Abstract: A taking lens system for forming an image on a solid-state image sensor has, from the object side thereof: an aperture stop, a first lens element having a positive optical power and convex to the object side, a second lens element having a positive optical power and convex to the image-surface side, and a third lens element having a negative optical power and concave to the image-surface side. Alternatively, a taking lens system for forming an image on a solid-state image sensor has an aperture stop, a first lens element having a positive optical power, having a meniscus shape, and convex to the object side, a second lens element having a positive optical power, and a third lens element having a negative optical power. In addition, in either case, the taking lens system fulfills prescribed conditional formulae.

Abstract: A three-piece lens assembly comprises: a first lens group, a second lens group, a third lens group and an aperture. The first lens group is a positive meniscus lens with a convex surface facing the object side and with another surface facing an aperture. The second lens group is a positive meniscus lens with a concave surface facing the aperture and the object side. The third lens group is a biconcave lens with a concave surface facing the second lens and the object side and with another surface facing the image side, and the concave surface of the third lens facing the object side is greater than the another surface of the third lens facing the image side in radius of curvature. Both sides of the first, second and third lens groups are aspheric and are all made of plastic material.

Abstract: A compact image pickup lens includes, in order from an object side to an image side, a first lens element G1 of positive refractive power, a second lens element G2 of positive refractive power, and a third lens element G3 of negative refractive power. The first lens element has a meniscus shape with its convex surface L1 on the object side. The second lens element also has a meniscus shape but with its convex surface L4 on the image side. Each of the first, second and third lens elements has at least one aspheric surface. An aperture STO is further positioned in front of the second lens element. The image pickup lens satisfies the following conditions: 0.85?(v1/v2)?1.15 and 0.85?(v2/v3)?1.25, where v1 is the Abbe number at the d-line (587.5618 nm) of the first lens element, v2 is the Abbe number at the d-line (587.5618 nm) of the second lens element, and v3 is the Abbe number at the d-line (587.5618 nm) of the third lens element.

Abstract: A macro lens system includes a positive first lens group, a diaphragm, a positive second lens group, and a negative third lens group. Upon focusing from an object at an infinite distance to an object at a closer distance, the positive first lens group and the positive second lens group integrally move toward the object without changing a distance therebetween, with respect to the negative third lens group which is stationary with respect to an imaging plane in a camera body. The positive first lens group includes a negative first sub-lens group and a positive second sub-lens group which are divided at a maximum distance between lens elements in the positive first lens group. The a macro lens system satisfies the following conditions: 0.32<d/f<0.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a convex surface directed to the object side on an optical axis and having a positive power; an aperture diaphragm placed between a top position of an object-side surface of the first lens and a position of an image-side surface of the first lens on the optical axis; a second lens having a meniscus shape with a concave surface directed to the object side on the optical axis; and a third lens having a meniscus shape with a convex surface directed to the object side on the optical axis. Further, the imaging lens satisfies specific conditional expressions.

Abstract: An image pickup lens includes in order from an object side of the image pickup lens: a first lens having positive refractive power whose convex surface faces the object side of the image pickup lens; an aperture stop; a meniscus shaped second lens having positive refractive power whose convex surface faces an image side of the image pickup lens; and a third lens having negative refractive power whose concave surface faces the image side of the image pickup lens, wherein the image pickup lens satisfies the following conditional expressions: 0.8<f1/f<2.0??(1) 20<((?1+?2)/2)??3<70??(2) where f1 is a focal length of the first lens, f is a focal length of a total system of the image pickup lens, and ?1, ?2 and ?3 are the Abbe constants of the first to third lenses respectively.

Abstract: A digital camera imaging lens includes first, second and third lenses arranged in sequence from an object side toward an imaging surface side. The first lens is a meniscus lens having a positive power, whose convex surface faces the object side. The second lens is a meniscus lens having a negative power, whose concave surface faces the object side. The third lens is an aspherical lens having an inflection point on its object-side surface. An aperture stop is disposed between the first and second lenses. The imaging surface is defined by an element surface of a photosensor.

Abstract: An imaging system includes a wavelength dependent aperture stop, which transmits light with different ranges of wavelengths through apertures of different diameters. Thus, different colored light will have different F-stops, which can be selected based on the power transfer and image quality requirements for the different colored light. For example, a smaller F-stop may be used with a weaker light source to produce a higher throughput for a specific range of wavelengths. Accordingly, the optical system's design and optimization is wavelength and F-stop dependent.

Abstract: An eyepiece includes, in order from the object side, a first lens with positive power, a second lens with positive power, and a third lens with negative power. The first lens is a positive meniscus lens with a convex surface facing the object side, and the eyepiece fails to have a fourth lens. The eyepiece satisfies the following conditions: 0.6<f1/f<1.2 ?2.0<f1-2/f3<?1.0 ?0.45<f3/f<?0.25 where f1 is the focal length of the first lens; f1-2 is a combined focal length of the first and second lenses and is a focal length where a diopter is ?1 m?1 when the focal length of the eyepiece is changed; f3 is the focal length of the third lens; and f is the focal length of the entire system of the eyepiece and is a focal length where a diopter is ?1 m?1 when the focal length of the eyepiece is changed.

Abstract: A photographing optical system includes at least one of a positive lens and diffractive optical element being provided closer to an object side of the system than an intersection P of a light axis and paraxial chief ray, and a negative lens, provided closer to an image side than the intersection. The positive lens and the negative lens are formed of materials satisfying the following conditions when the maximum height of a paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to the object side than the intersection is greater than a maximum height of the paraxial marginal ray, passing through a lens surface, from the light axis at a location closer to the image than the intersection: ?0.0015×?d+0.6425<?gF 60<?d where ?d is an Abbe number and ?gF is a partial dispersion ratio.

Abstract: A taking lens system for forming an image on a solid-state image sensor has, from the object side, two positive lens elements and at least one negative lens element. The most image-side lens surface is an aspherical surface concave to the image side, and this aspherical surface has a point of inflection.

Abstract: An image pickup lens for forming image of a subject on a solid-state image pickup element includes: a first lens having a positive refractive power in a meniscus shape whose convex surface faces to an object side of the image pickup lens; an aperture stop; a second lens having a positive refractive power in a meniscus shape whose convex surface faces to an image side of the image pickup lens; a third lens having a negative refractive power whose concave surface faces to an object side of the image pickup lens. The first lens, the aperture stop, the second lens and the third lens are arranged in this order form an object side of the image pickup lens. The first lens and the third lens satisfy a predefined conditional expression.

Abstract: An imaging lens includes, in sequence from the object side to the image plane side: a first lens with a convex object side surface and having a positive overall index of refraction; an aperture stop having a predetermined diameter; a second lens with a convex object side surface and having an overall positive index of refraction; and a third lens with a concave object side surface and an overall negative index of refraction. At least one surface of the first lens is formed as an aspherical surface. Both surfaces of the third lens are formed as aspherical surfaces, with the image side surface having an inflection point at which the curvature of the surface changes within the effective diameter range. The imaging lens provides superior optical characteristics and is compact and suited for use in mobile cameras installed in portable telephones, PDAs, and the like.

Abstract: A single focus wide-angle lens includes, in order from the object side: a first lens component of positive refractive power, having a meniscus shape, and having a convex object-side surface; a stop; a second lens component of positive refractive power, having a meniscus shape, having at least one aspheric surface, having a concave object-side surface, and being made of plastic; and a third lens component of negative refractive power, having a meniscus shape, having both surfaces of aspheric shape, having an image-side surface that is concave on the optical axis, and being made of plastic. The single focus wide-angle lens may include only three lens elements. Specified on-axis conditions are satisfied in order to reduce aberrations and to make the single focus wide-angle lens compact. Additionally, satisfying a condition related to the half-field angle at the maximum image height helps reduce aberrations.

Abstract: A taking lens system has two lens elements, namely, from the object side, a positive lens element and a meniscus lens element convex to the image side, wherein the focal length of the entire taking lens system and the axial thickness from the object-side surface of the positive lens element to the image-side surface of the meniscus lens element fulfill a prescribed relation. Alternatively, a taking lens system has two lens elements, namely, from the object side, a first lens element having a meniscus shape with a convex surface on the object side and having a positive optical power and a second lens element having a meniscus shape with a concave surface on the image side, wherein the focal lengths of the first and second lens elements fulfill a prescribed relation.

Abstract: A photographing lens includes first, second and third lens elements arranged in a sequence from an object side. The first lens element is a positive meniscus with a positive power, and has a convex surface convex to the object side. One of surfaces of the first lens element is aspherical. The second lens element is a positive meniscus with a positive power. The third lens element is a negative meniscus with a negative power, and has a concave surface oriented to the object side. The first, second and third lens elements satisfy conditions of: 0.49<|F2/F3|<1.0, and 0.5<F23/F<4 where F is a lens system composite focal length; F2 is a focal length of the second lens element; F3 is a focal length of the third lens element; and F23 is a composite focal length of the second and third lens elements.

Abstract: A single focus wide-angle lens includes, in order from the object side: a first lens component of positive refractive power, having a meniscus shape, and having a convex object-side surface; a stop; a second lens component of positive refractive power, having a meniscus shape, having at least one aspheric surface, having a concave object-side surface, and being made of plastic; and a third lens component of negative refractive power, having a meniscus or plano-concave or biconcave shape, having both surfaces of aspheric shape, having an image-side surface that is concave on the optical axis, and being made of plastic. The single focus wide-angle lens may include only three lens elements. Specified on-axis conditions are satisfied in order to reduce aberrations and to make the single focus wide-angle lens compact. Additionally, satisfying a condition related to the half-field angle at the maximum image height helps reduce aberrations.

Abstract: A lens system and a portable device employing the lens system are provided. The lens system includes at least three lenses and an infrared cut filter disposed between any of the lenses to prevent redness from occurring at a center region of an image as the lens system is miniaturized. An angle ?1 at which light is incident on the infrared cut filter satisfies 14°??1?16°.

Abstract: The present invention includes, from an object side to an image-plane side: an aperture stop with a predetermined diameter, a first lens with a positive refractive power having a convex surface on the object side, a second lens with a positive refractive power having a concave surface on the object side, and a third lens with a negative refractive power having a convex surface on the object side. The second and third lenses have aspherical surfaces on their object-side and image-plane-side surfaces. The third lens is formed with an inflection point where the curvature orientation changes within the effective diameter range of the aspherical surface on the image-plane side. An appropriate back focus is maintained while the total length of the lens system is reduced.

Abstract: The invention relates to an image-formation optical system that satisfies demands toward high performance and compactness at the same time, and an imaging system incorporating the same. The image-formation optical system comprises, in order from its object side, an aperture stop S, a first positive meniscus lens L1 convex on its object side, a second positive lens L2 having an aspheric surface and a third negative lens L3 having an aspheric surface, and satisfies the following condition. 0.95<?d/f<1.25??(1) Here ?d is the distance on an optical axis of the image-formation optical system from the object side-surface of the first positive meniscus lens to the image plane side-surface of the third negative lens, and f is the focal length of the image-formation optical system.

Abstract: A three-lens-element taking lens system for forming an image on a solid-state image sensor has, from the object side, a first lens element having a positive optical power, an aperture stop, a second lens element having a positive optical power, and a third lens element having a negative optical power and having a concave surface pointing to the image side. Of the first and second lens elements, one is a glass lens element and the other is a plastic lens element. The third lens element is a plastic lens element.

Abstract: An image forming optical system comprises, in order from an object side, a first positive meniscus lens having a convex surface directed toward an object side, an aperture stop, a second positive meniscus lens having a convex surface directed toward the object side and a negative lens. At least one of surfaces of the negative lens is a spherical and the following condition is satisfied: ?2.0<?m/?p<0 ?2.0<(r1r+r2f)/(r1r?r2f)<1.0 where ?m represents the power of the negative lens at the position of the maximum light height and ?p represents the power of the negative lens at the position of the near axis, r1r represents the radius of curvature of the first lens at the image side and r2f is the radius of curvature of the second lens at the object side.

Abstract: A photographing lens includes an aperture stop having a predetermined aperture, a first lens having a positive refractive power and a convex surface facing the object side, a second lens having a positive refractive power and aspherical surfaces on both sides, the object-side aspherical surface being concave, and a third lens having a negative refractive power and aspherical surfaces on both sides, the object side surface being convex. The aperture stop and the first, second, and third lenses are arranged in order from the object side toward the image-plane side. With such a three-unit, three element lens configuration, a proper back focus is ensured, aberrations are properly corrected, and the total lens length and thickness of the photographing lens are reduced. The photographing lens can be suitably applied to high-resolution image pickup devices with a million pixels or more.

Abstract: The present invention is an imaging lens in which various aberrations are satisfactorily corrected, the optical length is short, and a sufficient back focus is secured. The imaging lens is constituted by arranging a first lens L1, an aperture diaphragm S1, a second lens L2, and a third lens L3 in succession from the object side to the image side.

Abstract: Provided is an imaging lens system comprising: a first lens in a meniscus shape having a positive power whose convex surface facing an object side; a second lens in a meniscus shape having a positive power whose concave surface facing the object side; and a third lens having a negative power whose concave surface facing the object side. The three lenses are disposed in order from the object side to the image surface side.

Abstract: In an imaging lens of the present invention, aberration is satisfactorily corrected, the optical length is short, and sufficient back focus is secured. The imaging lens of the present invention is constituted by arranging a first lens L1, an aperture diaphragm S1, a second lens L2, and a third lens L3 in succession from the object side to the image side.

Abstract: A bright, small, and inexpensive imaging lens system is provided with a short total length that can provide more than a 30 degree viewing angle and whose aberrations are excellently corrected. The imaging lens includes, in order from an object side, a positive first lens with a convex surface facing the object side, an aperture stop provided on the object side or an image side of the first lens, a meniscus second lens with a concave surface facing the object side, and a meniscus third lens with a convex surface facing the object side. Furthermore, at least one of the first lens and the second lens includes an aspheric surface, and the third lens is a biaspheric lens. In addition, the second lens and the third lens have paraxial focal lengths whose signs are different. When v max and v min are the maximum Abbe number and the minimum Abbe number among the lenses, respectively, the condition, 1.25<v max/v min, is satisfied.

Abstract: A compact zoom lens system allowing excellent image quality regardless of an object distance, is disclosed. The disclosed zoom lens system comprises, in order from an object side to an image side, a first, a second, and a third lens units having a positive, a positive, and a negative optical powers, respectively. The spacings between the first and second lens units and between the second and third lens units are changed during zooming. The second lens unit is constituted by, in order from the object to image side, a first lens subunit having a positive or negative optical power and a second lens subunit having a positive optical power. At least the second lens subunit is moved toward the object side to change the spacing between the first and second lens subunits during focusing on an object at a short distance from an object at infinity at least one zoom position.

Abstract: The invention relates to an image-formation optical system that satisfies demands toward high performance and compactness at the same time, and an imaging system incorporating the same. The image-formation optical system comprises, in order from its object side, an aperture stop S, a first positive meniscus lens L1 convex on its object side, a second positive lens L2 having an aspheric surface and a third negative lens L3 having an aspheric surface, and satisfies the following condition.

Abstract: An imaging lens includes, in order from the object side, a positive meniscus first lens component with its convex lens surface on the object side, a positive meniscus second lens component with its convex lens surface on the image side, and a negative third lens component with its concave lens surface on the image side. At least both lens surfaces of the negative third component are aspheric, and all six lens surfaces of the three lens components may be aspheric. The negative refractive power of the third lens component gradually decreases from the center of the third lens component toward the periphery of said third lens component and the peripheral region of the third lens component, outside 70% of its radius, has positive refractive power. The imaging lens may consist of only three lens components or elements. A diaphragm is positioned between the first and second lens components.

Abstract: A photographing lens includes an aperture stop having a predetermined aperture, a first lens having a positive refractive power and a convex surface facing the object side, a second lens having a positive refractive power and aspherical surfaces on both sides, the object-side aspherical surface being concave, and a third lens having a negative refractive power and aspherical surfaces on both sides, the object side surface being convex. The aperture stop and the first, second, and third lenses are arranged in order from the object side toward the image-plane side. With such a three-unit, three element lens configuration, a proper back focus is ensured, aberrations are properly corrected, and the total lens length and thickness of the photographing lens are reduced. The photographing lens can be suitably applied to high-resolution image pickup devices with a million pixels or more.

Abstract: A single-lens reflex camera provided with an eyepiece includes a screen on which an image of an object is projected, a plurality of reflecting surfaces for erecting the image projected on the screen, and an eyepiece with positive refracting power for observing the image. In this case, the eyepiece has, in order from the object side, a first lens component with positive refracting power, a second lens component with positive refracting power, and a third lens component with negative refracting power and satisfies the following conditions: 0.15<tan S<0.35 2.00<fb/Y<5.00 −0.67<f3/f<−0.

Abstract: A taking lens system for forming an image on a solid-state image sensor has, from the object side, two positive lens elements and at least one negative lens element. The most image-side lens surface is an aspherical surface concave to the image side, and this aspherical surface has a point of inflection.

Abstract: A telescopic lens system includes a positive first lens group, and a positive second lens group. The first lens group includes cemented lens elements having a positive lens element and a negative lens element. The second lens group includes cemented lens elements having a positive lens element and a negative lens element.

Abstract: An immersion microscope objective lens comprises a first lens group G1 having a positive refracting power, a second lens group G2 having a positive refracting power and a third lens group G3 having a negative refracting power in the order from the object side. The first lens group G1 has a first cemented lens consisting of a plano-convex lens with the flat surface facing the object side and a meniscus lens with the convex lens facing the image side cemented together, a positive lens with the surface having a greater refractive power facing the image side, and a second cemented lens consisting of a negative lens and a positive lens cemented together, in the order from the object side. The second lens group G2 has a cemented lens consisting of a negative lens and a positive lens cemented together. The refractive index n12 of the meniscus lens in the first lens group G1 with respect to the d-line satisfies the following condition: n12>1.9.

Abstract: A photographing lens system includes an aperture stop, a first lens group, a second lens group, and a third lens group, in this order from the object. The first lens group includes a positive first lens element, and a negative second lens element which is cemented to or separate from the positive first lens element. The second lens group only includes a positive third lens element having an aspherical surface formed on at least one refractive surface thereof. The third lens group only includes a negative fourth lens element having an aspherical surface formed on at least one refractive surface thereof.

Abstract: An eyepiece lens is constructed with, in order from an entrance side for light to an exit side for light, first, second, third, fourth and fifth lens units of negative, positive, positive, positive and positive refractive powers, respectively. Each of the first, second, third, fourth and fifth lens units of the eyepiece lens is composed only of one lens or a cemented lens, and an intermediate image by an objective lens is formed between the second lens unit and the third lens unit. An objective lens is constructed with, in order from an object side to an image side, first and second lens units of positive and negative refractive powers, respectively. The first and second lens units of the objective lens are composed of one positive lens and of one positive lens and one negative lens, respectively, and the various conditions are appropriately set. An optical apparatus includes the eyepiece lens, the objective lens and an erecting prism.

Abstract: The object of the invention is to reduce the size of a camera by the provision of a zoom lens system which has a high zoom ratio and a small telephoto ratio at the wide-angle and telephoto end, and is simple in lens arrangement and reduced in size during lens collapsing. The zoom lens system comprises a positive first lens group G1, a positive second lens group G2 and a negative third lens group G3. For zooming from a wide-angle end to a telephoto end of the system, each lens group moves toward the object side while a spacing between the first lens group and the second lens group becomes wide and a spacing between the second lens group and the third lens group becomes narrow. The first lens group G1 comprises at least one set of a negative lens and a positive lens. The second lens group G2 includes an aperture stop and comprises at least one set of a negative lens and a positive lens. The third lens group G3 comprises one set of a positive lens and a negative lens.

Abstract: A variable focal length optical system of reducing size and increased zoom ratio is provided. According to one aspect. at least three lens groups, in order from an object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a positive refractive power, and a third lens group G3 having a negative refractive power. When a state of lens group positions is changed from a wide-angle end state to a telephoto end state, each lens group moves to the object side such that an air gap between the first lens group G1 and the second lens group G2 increases, and an air gap between the second lens group G2 and the third lens group G3 decreases. An aperture diaphragm is arranged between the first lens group G1 and the third lens group G3. The second lens group G2 is arranged in the vicinity of the aperture diaphragm and has a positive lens having double aspherical surfaces. Particular conditions are satisfied.

Abstract: A variable focal length lens system includes at least three lens groups, in order from an object side, a first lens group G1, a second lens group G2, and a third lens group G3. When the lens group positions are changed from a wide-angle end state to a telephoto end state, each lens group moves from a state focused at infinity to a state focused at near object, in order from a state focused at infinity in the wide-angle end state to a state focused at near object in the telephoto end state. G2 has an aperture diaphragm S, and lens elements are arranged to both object and image side of the aperture diaphragm S.