Abstract: There is provided an imaging lens with high-resolution which satisfies demand of wide field of view, low-profileness and low F-number in well balance, and excellently corrects aberrations. An imaging lens comprises, in order from an object side to an image side, a first lens, a second lens having negative refractive power near the optical axis, a third lens having a convex surface facing the image side near the optical axis, a fourth lens and a fifth lens, wherein said first lens has negative refractive power near the optical axis, an image-side surface of said fifth lens has a convex surface facing the image side near the optical axis, and below conditional expressions are satisfied: 3.00<(T4/f)×100<5.90 0.40<f2/f5<1.

Abstract: An optical imaging system including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens disposed in order from an object side, wherein one or more of the first to sixth lenses is disposed between a stop and an imaging plane and of those, one or more has positive refractive power and one is made of a glass material, and four or more of the first to sixth lenses are made of a plastic material.

Abstract: An optical lens of the present disclosure assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, an optical filter and a sensor. The optical lens also has an axis. The first lens element and the fifth lens element have negative power, the second lens element, the third lens element, the fourth lens element and the sixth lens element have positive power.

Abstract: A first lens and a second lens are bonded to each other and configured to be short in an optical axis direction. Further, by providing a half mirror in a bonding portion between a convex surface and a concave surface, power is given when folding an optical path, and additionally, by setting a refractive index of the first lens larger than a refractive index of the second lens, an image with a wide angle of view can be formed.

Abstract: A first lens and a second lens are bonded, and each of a light emitting plane and a light incident plane is a flat surface to shorten a configuration in an optical axis direction, and simultaneously, various optical elements such as a transmission/reflection selection member and the like can be mounted on a flat surface portion. Further, by providing a half mirror in a bonding portion between a convex surface and a concave surface to give power in folding an optical path, an image with a wide angle of view can be formed.

Abstract: An imaging lens includes a first lens having a negative refractive power and a meniscus shape with a convex surface facing an object side; a second lens having a negative refractive power and a meniscus shape with a convex surface facing an object side; a third lens having a positive refractive power and a meniscus shape with a convex surface facing an object side; an aperture diaphragm; a fourth lens having a positive refractive power and a biconvex shape; a fifth lens having a negative refractive power and a biconcave shape and; and a sixth lens having a positive refractive power and a biconvex shape. The imaging lens as a whole is formed with the six lenses in six groups with six independent lenses, the imaging lens has a full angle of view of 150 degrees or more, and the imaging lens satisfies predetermined conditional expressions.

Abstract: A photographing optical lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with negative refractive power has an image-side surface being concave. The second lens element has an image-side surface being concave. The fourth lens element has an image-side surface being convex. The sixth lens element has an object-side surface being concave. The photographing optical lens assembly has a total of six lens elements.

Abstract: A six-piece optical lens for capturing image and a six-piece optical module for capturing image are provided. In order from an object side to an image side, the optical lens along the optical axis includes a first lens with refractive power, a second lens with refractive power, a third lens with refractive power, a fourth lens with refractive power, a fifth lens with refractive power and a sixth lens with refractive power. At least one of the image-side surface and object-side surface of each of the six lens elements is aspheric. The optical lens can increase aperture value and improve the imagining quality for use in compact cameras.

Abstract: A wide-angle lens may include a first lens having negative power; a second lens being a plastic lens having negative power, wherein at least one of an object side lens face and an image side lens face is an aspherical surface; a third lens being a plastic lens having negative power, wherein at least one of an object side lens face and an image side lens face is an aspherical surface; a fourth lens having positive power; a fifth lens being a plastic lens; a sixth lens being a plastic lens, wherein the fifth lens and the sixth lens constitute a cemented lens having positive power; and a diaphragm disposed between the fourth lens and the cemented lens. The effective focal length “f” and the focal length “f3” may satisfy the relationship: |f/f3|<0.2.

Abstract: A wide angle lens consists essentially of a front group and a rear group in this order from an object side. The front group consists essentially of two negative lenses and a positive lens in this order from the object side, and all of the three lenses are made of an identical material. The rear group includes at least one positive lens and at least one negative lens, and a lens closest to an image side in the rear group is a negative lens. When a refractive index for d-line of the material of the lenses in the front group is NF, conditional expression (1): 1.48<NF<1.6 is satisfied.

Abstract: An image forming lens consists of from an object side to an image side in the following order: a first group with a positive refractive power; an aperture stop; and a second group with a positive refractive power, wherein the second group includes, from the object side to the image side in the following order, a biconvex lens, a biconcave lens, a negative meniscus lens a convex surface of which faces the image side, a biconvex lens, and a positive meniscus lens a convex surface of which faces the image side.

Abstract: A near-infrared laser focusing lens and a laser printing device are provided. The lens comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens (L1, L2, L3, L4, L5) which are coaxially arranged along a transmission direction of incident light rays, wherein the first lens (L1) is a negative plane-concave lens; the second lens and the third lens (L2, L3) are positive biconvex lenses; and the fourth lens and the fifth lens (L4, L5) are positive meniscus lenses; and a concave surface (S2) of the first lens (L1) is opposite to the second lens (L2), and the middle parts of the fourth lens and the fifth lens (L4, L5) both reversely protrude towards the transmission direction of light beams. After the shapes and the relative locations of the lenses are designed, the near infrared light can be clearly imaged, and the geometrical aberration of the lens can be effectively corrected, so as to obtain a clear flat field.

Abstract: An optical image capturing lenses includes, in order from an object side to an image side, a first lens element with refractive power, a second lens element with negative refractive power, a third lens element with refractive power, a fourth lens element with positive refractive power, a fifth lens element with refractive power and a sixth lens element with refractive power. The first lens element has a convex object-side surface and a concave image-side surface. The second lens element has a convex object-side surface and a concave image-side surface. The fifth lens element is made of plastic material, and two surfaces of the fifth lens element are aspheric. The sixth lens element has a convex object-side surface and a concave image-side surface and is made of plastic material, the surfaces of the sixth lens element are aspheric, and the image-side surface thereof has at least one inflection point.

Abstract: A wide-angle lens includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens, all of which are arranged in sequence from an object side to an image side along an optical axis. The first lens is with negative refractive power and includes a concave surface facing the image side. The second lens is a biconcave lens with negative refractive power. The third lens is a biconvex lens with positive refractive power. The fourth lens is a biconvex lens with positive refractive power. The fifth lens is with negative refractive power and includes a concave surface facing the object side.

Abstract: The present invention relates to a super wide angle optical lens system reduced in size and weight and increased in definition for various electronic devices and vehicles while capable of obtaining satisfactory optical performance, an appropriate wide field angle and exhibiting high image quality and broad image data, thereby reducing distortion of an image.

Abstract: In a zoom lens of a fixed total length, at the time of changing the magnification from the wide-angle end toward the telephoto end, the first lens group is anchored while the second lens group is moved, and the third and fourth lens groups are moved so as to be located at the object side of the telephoto end relative to the wide-angle end, such that: the interval between the second and third lens groups is decreased at the telephoto end relative to the wide-angle end; the interval between the third and fourth lens groups is increased at the telephoto end relative to the wide-angle end; and the interval between the fourth and fifth lens groups is increased at the telephoto end relative to the wide-angle end, and at the time of focusing a near object point from a remote object point, the second lens group is moved.

Abstract: An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. An object-side surface of the second lens has a shape having negative refractive power at a center, and including a part having positive refractive power in an area between the center and an effective diameter edge, and having negative refractive power at the effective diameter edge (concave shape facing the object side), and the refractive power at the effective diameter edge being weaker than the refractive power at the center. Further, an object-side surface of the third lens is convex toward the object side. Further, a predetermined conditional formula about a combined focal length of the first lens, the second lens and the third lens is satisfied.

Abstract: An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. An object-side surface of the second lens has a shape having negative refractive power at a center, and including a part having positive refractive power in an area between the center and an effective diameter edge, and having negative refractive power at the effective diameter edge (concave shape facing the object side), and the refractive power at the effective diameter edge being weaker than the refractive power at the center. Further, an object-side surface of the third lens is convex toward the object side. Further, a predetermined conditional formula about a combined focal length of the first lens, the second lens and the third lens is satisfied.

Abstract: An imaging lens substantially consists of six lenses of a negative first lens, a negative second lens, a positive third lens, a positive fourth lens, a negative fifth lens and a positive sixth lens in this order from an object side. An object-side surface of the second lens is concave, and an object-side surface of the third lens is concave. A predetermined conditional formula about a combined focal length of the fourth lens and the fifth lens is satisfied.

Abstract: According to exemplary embodiments of the present invention, an imaging lens includes, in an ordered way from an object side, a first lens having negative (?) refractive power, a second lens having negative (?) refractive power, a third lens having positive (+) refractive power, a fourth lens having positive (+) refractive power, a fifth lens having negative (?) refractive power, and a sixth lens having negative (?) refractive power, wherein, a conditional expression of 0.5<Y6/Y10<0.55 is satisfied, where a height of a point 60% of a highest height of an image-forming surface is Y6, a full size of an opposite angle within an active area of an image sensor is Y10.

Abstract: An image forming lens including an aperture stop, a first lens group, and a second lens group having a positive power, the first lens group including a first F lens group having a negative power and a first R lens group having a positive power, the first F lens group including at least two negative lenses, the first R lens group including at least one positive lens, the second lens group including a second F lens group having a positive power and a second R lens group, the second F lens group including a first positive lens, a first negative lens, a second negative lens, and a second positive lens, and the second R lens group including at least one lens.

Abstract: An optical image capturing lenses includes, in order from an object side to an image side, a front lens group, a stop, and a rear lens group. The front lens group includes, in order from the object side to the image side, at least a first lens element and a second lens element. The first lens element has a convex object-side surface and a concave image-side surface. The rear lens group includes, in order from the object side to the image side, at least a third lens element, a fourth lens element, a fifth lens element, and a sixth lens element. The sixth lens element is made of plastic material. The object-side surface and the image-side surface of the sixth lens are aspheric. The sixth lens element has at least one inflection point formed on at least one of the object-side surface and the image-side surface thereof.

Abstract: An image-forming lens includes: from an object side to an image side in order, a first group with a positive refractive power which includes less than or equal to five lens elements of two negative lenses and equal to or more than two positive lenses and in which a first lens element on a most object side is a negative meniscus lens a convex surface of which faces the object side; an aperture; and a second group with a positive refractive power which includes less than or equal to five lens elements including at least one cemented lens of a positive lens and a negative lens; wherein each of the first group and the second group shifts independently to perform focusing to a limited object distance, and an interval between the first lens element and a second lens element close to a surface on the image side of the first lens element: d11-2 and an interval between the second lens element and a third lens element close to a surface on the image side of the second lens element: d12-3 satisfy Conditional Expression

Abstract: The present invention relates to a super wide angle optical lens system reduced in size and weight and increased in definition for various electronic devices and vehicles while capable of obtaining satisfactory optical performance, an appropriate wide field angle and exhibiting high image quality and broad image data, thereby reducing distortion of an image.

Abstract: A lens system with positive refraction power, in order from the object-side to the image-side, includes a first lens group with negative refraction power and a second lens group with positive refraction power. The first lens group includes a first lens with negative refraction power, a second lens with positive refraction power, and a third lens with positive refraction power. The second lens group includes a fourth lens with negative refraction power, a fifth lens, and a sixth lens. The lens system satisfies the following condition: 5<D/F<5.3, wherein: D is a total length of the lens system; F is a focal length of the lens system.

Abstract: An image forming lens including an aperture stop, a first lens group arranged on the object side relative to the aperture stop, and a second lens group having a positive power arranged on an image side relative to the aperture stop, the first lens group including a first F lens group having a negative power and a first R lens group having a positive power arranged in this sequence from the object side with the widest air space between the first F lens group and the first R lens group, the first F lens group including at least two negative lenses, the first R lens group including at least one positive lens, the second lens group including a second F lens group having a positive power and a second R lens group arranged in this sequence from the object side, the second F lens group including a first positive lens, a first negative lens, a second negative lens, and a second positive lens arranged in this sequence from the object side, and the second R lens group including at least one lens.

Abstract: An imaging lens is provided and includes, in order from the object side, a front group having a negative power, a stop, and a rear group having a positive power. The front group includes, in order from the object side, a first negative lens having a meniscus shape with a concave surface on an image side, a second negative lens, and a third positive lens. The rear group includes, in order from the object side, a fourth positive lens, a fifth negative lens having a meniscus shape with a concave surface on the object side, and a sixth positive lens. An Abbe number of each of the first lens, the second lens, the fourth lens, and the sixth lens at the d-line is equal to or larger than 40, and an Abbe number of each of the third lens and the fifth lens at the d-line is equal to or smaller than 40. Each lens constituting the front group and the rear group is a single lens.

Abstract: This invention provides an imaging optical lens assembly, in order from an object side to an image side comprising: a front lens group, an aperture stop and a rear lens group; wherein the front lens group comprises, in order from the object side to the image side: a first lens element with negative refractive power having a concave image-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power and a fourth lens element with positive refractive power; wherein the rear lens group comprises, in order from the object side to the image side: a fifth lens element with positive refractive power; and a sixth lens element with negative refractive power; wherein the fifth lens element and the sixth lens element are connected to form a doublet. By such arrangement, sufficient field of view is provided, and the aberration of the lens assembly is corrected for obtaining high image resolution.

Abstract: An optical system includes, in order from an object side to an image side, a first lens having a negative refractive power and having a meniscus shape whose surface on the object side has a convex shape and whose surface on the image side has an aspheric shape, a second lens having a negative refractive power, and a third lens having a negative refractive power. In the optical system, a focal length of the entire optical system (f), a focal length of the first lens (f1), and respective radii of curvature of lens surfaces of the second lens on the object side and on the image side (G2R1, G2R2) satisfy the following conditions: ?1.6<f1/f<?1.2 0.1<(G2R1?G2R2)/(G2R1+G2R2)<0.5.

Abstract: An image system adapted to a projection display apparatus includes a first lens group having a negative refractive power, a second lens group having a positive refractive power, an aspheric reflector, and a curved reflector. The second lens group includes an aspheric lens which is the nearest to the light valve in the second lens group. A material of the aspheric lens includes glass, the thermal-optical coefficient of the glass is between 1.0×10?6/K and 12.5×10?6/K, and the refractive index of the glass is between 1.482 and 1.847. The aspheric reflector is disposed front of the first lens group for reflecting the image beam passing through the first lens group and second lens group. The curved reflector is disposed above the first lens group for reflecting the image beam reflected by the aspheric reflector onto the screen. The image system has a good imaging quality.

Abstract: An imaging lens system is provided an includes: in order from the object side, a first lens which has a negative power; a second lens which has a negative power; a third lens; a fourth lens which has a positive power; a fifth lens; and a sixth lens which has a positive power. The first lens is made of glass, and the second to sixth lenses are made of plastic. At least one lens surface of each of the second to sixth lenses is aspheric, and each of the third lens and the fifth lens is made of a material having an Abbe number of 45 or less at the d-line.

Abstract: There is provided a super wide angle optical system including, arranged about an optical axis: a first lens having a negative refractive power and having a meniscus shape with a convex object-side surface; a second lens having a negative refractive power and having a meniscus shape with a convex object-side surface; a third lens having a positive refractive power and having both convex surfaces; a fourth lens having a positive refractive power; a fifth lens having a negative refractive power; and a sixth lens having a positive refractive power and having both convex surfaces.

Abstract: A wide angle lens especially suitable for digital single lens reflex cameras is described. The lens offers the advantages of superior performance while using fewer lens elements thus reducing size and cost to manufacture. The lens consists of two lens groups separated by an aperture stop. The first lens group consists of a meniscus lens and the novel use of a bi-concave lens element. The first group may also include a cemented doublet with novel ratios of refractive index and Abbe numbers. Embodiments of the wide angle lens satisfy conditional equations of 6?BFL/f?7.5 and 10<?d/f?21, where BFL is the distance from the most image side lens element surface to the image plane with the lens focused at infinity, f is the effective focal length of the wide angle lens and ?d is the distance from the most object side lens element surface to the most image side lens element surface.

Abstract: A super wide angle optical system including: a first lens group including one or more of irrotational symmetric lens surfaces disposed sequentially from an object side and having, overall, a negative refractive power; an aperture stop for intercepting unnecessary light; and a second lens group including one or more of irrotational symmetric lens surfaces and having, overall, a positive refractive power.

Abstract: A small projection lens includes a first lens, which is a biconvex lens, an aperture, an aperture diaphragm (or an aperture), a second lens, which is a negative meniscus lens having a concave surface facing a magnification side, a third lens, which is a positive meniscus lens having a convex surface facing a reduction side, and a fourth lens, which is a biconvex lens having aspheric surfaces at both sides on an optical axis, arranged in this order from the magnification side. A minimum portion of the length of all lens elements of the small projection lens in a diametric direction vertical to the optical axis is equal to or less than 15 mm, and the small projection lens satisfies the following conditional expression: 2.5<?/S<10.0 (where S indicates the maximum length of a magnification-side image (inch) and ? indicates a magnifying power).

Abstract: A lens unit includes a front group, a stop, and a rear group, in order from the object side toward the image side. The front group includes at least: a first lens having a negative meniscus shape; a negative second lens formed from a plastic and having an aspherical surface; and a positive third lens, in order from the object side toward the image side. The rear group includes at least: a positive first lens; and a negative second lens, in order from the object side toward the image side.

Abstract: An image forming optical system which comprises a negative lens unit and a positive lens unit arranged in order from an object side. The negative lens unit includes, in order from the object side, a first negative lens and a second negative lens, or a first negative lens, a second negative lens and a third negative lens. The positive lens unit includes, in order from the object side, a third positive lens, a fourth negative lens, a fifth positive lens and a sixth positive lens, or a fourth positive lens, a fifth negative lens, a sixth positive lens and a seventh positive lens.

Abstract: The imaging lens is provided and includes: in order from the object side, a negative first lens whose concave surface is directed toward the image side; a second lens of a planoconcave lens whose flat surface is directed toward the object side or a biconcave lens whose surface having a larger absolute value of radius of curvature is directed toward the object side; a third biconvex lens; a stop; a positive fourth lens whose surface having a smaller absolute value of radius of curvature is directed toward the image side; and a cemented lens of a positive fifth lens of biconvex shape and a negative sixth lens of meniscus shape, the cemented lens having a positive refractive power, and an Abbe number ?3 at d-line of the third lens satisfies a conditional expression (1) ?3<43.

Abstract: A zoom lens comprises a plurality of lens units including a first lens unit disposed most adjacent to an enlargement side and having negative refractive power, wherein one or more lens units of the plurality of lens units are moved in the direction of the optical axis thereof during magnification change, and wherein the first lens unit includes a 1-1st lens unit comprising at least one lens of negative refractive power and moved during focusing and a 1-2nd lens unit having positive refractive power, and fixed during focusing.

Abstract: To provide a high-brightness, small, low-cost optical apparatus which covers a wide-angle to super-wide-angle region and which reliably corrects various aberrations with a small number of lenses. At least one negative lens unit 1, a meniscus lens 2 that is convex on an object side, an aperture stop S, and a double-convex positive lens 3 are arranged in order from the object side. At least one of the lenses positioned on the object side of the aperture stop S and the positive lens 3 include respective aspherical surfaces.

Abstract: A zoom lens comprises a plurality of lens units including a first lens unit disposed most adjacent to an enlargement side and having negative refractive power, wherein one or more lens units of the plurality of lens units are moved in the direction of the optical axis thereof during magnification change, and wherein the first lens unit includes a 1-1st lens unit comprising at least one lens of negative refractive power and moved during focusing and a 1-2nd lens unit having positive refractive power, and fixed during focusing.

Abstract: A front group is formed of a negative first lens as a meniscus lens which is convex at the object side and a negative second lens, and a rear group is formed of a biconvex positive third lens, an aperture stop, a negative fourth lens and a biconvex positive fifth lens. The first lens is a glass lens, and the second lens is a plastic aspherical lens. The following conditions are satisfied: ?2.4<fI/f<?1.55, 0.15<f2/f1<0.35, va<29, and vb>50, where f denotes a focal distance of a whole system, f1 denotes a focal distance of the first lens, f2 denotes a focal distance of the second lens, fI denotes a focal distance of the front group, va denotes an average value of abbe numbers of the third and the forth lenses, and vb denotes an average value of abbe numbers of the rest of the lenses.

Abstract: A zoom lens comprises a plurality of lens units including a first lens unit disposed most adjacent to an enlargement side and having negative refractive power, wherein one or more lens units of the plurality of lens units are moved in the direction of the optical axis thereof during magnification change, and wherein the first lens unit includes a 1-1st lens unit comprising at least one lens of negative refractive power and moved during focusing and a 1-2nd lens unit having positive refractive power, and fixed during focusing.

Abstract: A fisheye lens system with a half angle-of-view of 90° includes a negative front lens group, a diaphragm, and a positive rear lens group. The negative front lens group includes at least three negative meniscus lens elements each of which has the convex surface facing toward the object; and the three negative meniscus lens elements satisfy the following conditions: 0.2<SF(i=1)<0.6??(1) 0.8<SF(i=2)/SF(i=1)<1.5??(2) 0.8<SF(i=3)/SF(i=1)<2.0??(3) wherein SFi designates the shaping factor of the ith (1?i?3) negative meniscus lens element (SFi=(R1i?R2i)/(R1i+R2i)); R1i designates the radius of curvature of the object-side surface of the ith (1?i?3) negative meniscus lens element; and R2i designates the radius of curvature of the image-side surface of the ith (1?i?3) negative meniscus lens element.

Abstract: A zoom lens, having a camera shake correction function, that is capable of preventing degradation of chromatic aberration while correcting camera shake, and can be small, light-weight and power-saving, is provided. The zoom lens is composed of four groups of lenses having positive, negative, positive and positive refractive powers, arranged in that order from an object side to an image plane side, where a second lens group conducts zooming and a fourth lens group conducts focus adjustment. The second lens group is made of a concave meniscus lens, a concave lens, a double convex lens, and a concave lens, arranged in that order from the object side to the image plane side, and it includes also at least one aspheric surface. A third lens group includes a cemented lens having a cemented surface whose convex surface faces the object side, and can be shifted in a perpendicular direction with respect to an optical axis in order to correct image fluctuations during a camera shake.

Abstract: A lens assembly comprising nine lenses. Each lens includes u greater than or equal to about 12.8°, LEP equal to or from about 100 mm to about 400 mm, &agr; Rba greater than or equal to about 1°, and &agr; Rbi less than or equal to about −14°. The outward ray angle tilt and the inward ray angle tilt are positive if the outward ray and the inward ray intersect the optical axis at a location which, when seen from the object, is in an opposite direction to projection. The outward ray angle tilt and the inward ray angle tilt are negative if the outward ray and the inward ray intersect the optical axis at a location which, when seen from the object, is in the direction of projection.

Abstract: Projection lenses (13) for use with pixelized panels (PP) are provided. The projection lenses have a negative first unit (U1) which has at least one aspheric surface and a positive second unit (U2) which has three subunits (US1, US2, US3) which have a positive/negative/positive configuration. The lens' aperture stop (AS) is located at the short conjugate end of the lens and is either in the third subunit (US3) or close to that subunit. The lenses are particularly well-suited for use in the manufacture of compact projection systems which employ side illumination of a reflective pixelized panel.

Abstract: There are provided a zoom lens system comprising, in order from a more distant conjugate point, a first lens unit of a negative refractive power, a second lens unit of negative refractive power which moves during zooming, third, fourth and fifth lens units, and at least one diffraction optical element.

Abstract: An optical system includes a diffractive optical element in which a phase given to incident light from an optical axis toward the peripheral part in the radial direction is not reversed in an effective area and an absolute value of optical power on the optical axis is made minimum. In the optical system, chromatic aberration of magnification of a high order is satisfactorily corrected and flare caused by additional diffraction light (unnecessary diffraction light) is suppressed to as minimum as possible while maintaining a high imaging performance up to peripheral part of a field angle.

Abstract: A zoom lens system of compact size having a small number of lenses and a large field area is provided, comprising, in the following order from the object side, a first lens group G1 with a negative refractive power and a second lens group G2 with a positive refractive power, wherein zooming is executed by changing dead space between lens groups G1 and G2. The first lens group G1 comprises, in the following order from the object side, a first lens group front group G.sub.1F with a negative refractive power, and a first lens group rear group G.sub.1R with either a negative refractive power or a positive refractive power having at least one set of color erasable negative lens components L.sub.n and positive lens components L.sub.p. Focusing is executed by moving only front group G.sub.1F.