Abstract: A macro lens and an imaging apparatus include, in the order from an object side to an image side, a first lens group, a second lens group, and a third lens group. Focusing is performed by fixing the first lens group and the third lens group, and by moving the second lens group having a positive refractive power as a whole on the optical axis in focusing from an infinite object to a close distance object. The first lens group has a plane S1 and a plane S2 of curvature radii of a same sign and satisfying a specified condition.

Abstract: A wide converter lens that is disposed on an object side of a main lens and changes the viewing angle, wherein the wide converter lens includes: a first lens having a negative refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power, wherein the first lens, the second lens, and the third lens are sequentially ordered from the object side to the image side, and the wide converter lens satisfies the following inequality: 2vd?50 where 2vd is an Abbe number of the second lens.

Abstract: A light condensing lens includes a plurality of lenses disposed side by side in a splitting direction of a view angle to condense incident light over a range corresponding to respective split portions of the view angle. The view angle is split in a direction orthogonal to an optical axis of the incident light.

Abstract: A projection lens includes a first lens group, a second lens group and a third lens group, all of which are arranged in sequence from an projection side to an image source side along an optical axis. The first lens group is with negative refractive power and includes four lenses. The second lens group is with positive refractive power and includes two lenses. The third lens group is with positive refractive power and includes a stop and six lenses.

Abstract: An optical system WL has, in order from an object, a first lens group G1 having negative refractive power and a second lens group G2 having positive refractive power, wherein the first lens group G1 is fixed and the second lens group G2 moves upon focusing from an object at infinity to an object at a finite distance, and the second lens group G2 is formed of a front group G2a located closer to the object than an aperture stop S disposed in the second lens group G2, and a rear group G2b located closer to an image than the aperture stop S.

Abstract: A light directing system including first and second relay lenses through which light passes, the first and second relay lenses being positioned at conjugate positions, the first relay lens being positioned between the second relay lens and a light source, a focal length of the first relay lens being longer than a focal length of the second relay lens.

Abstract: What is described is a modified retrofocus-type wide-angle lens, with, as seen from the object, a front group (G1) with negative refractive power, a first rear group (Gh1) with positive refractive power displaceable along the optical axis for focusing purposes and a second rear group (Gh2) with positive refractive power facing an image plane.

Abstract: A superwide-angle lens system includes a negative first lens group, an aperture diaphragm, and a positive second lens group. The first lens group includes two negative meniscus lens elements, and a positive lens element. The second lens group includes a cemented lens having negative and positive lens elements; and a positive lens element. The following conditions (1) and (2) are satisfied: ?1.45<f12/f<?1.15??(1) 1.4<SF2<2.4??(2) f12: the combined focal length of the two the negative meniscus lens elements in the first lens group, f: the focal length of the lens system, SF2: the shaping factor of the negative meniscus lens element on the image side in the first lens group.

Abstract: A fisheye lens system and a photographing apparatus including the fisheye lens system. The fisheye lens system includes, in an order from an object to an image, a first lens group including at least three lenses and having negative refractive power; and a second lens group having positive refractive power, wherein the at least three lenses included in the first lens group include a first lens, a second lens, and a third lens, in the order from the object to the image.

Abstract: Wide-angle projection lens, as well as optical engines and projection display devices comprising such projections lens are described. In one embodiment, a wide-angle projection lens is described comprising in sequential order from a screen side a first lens group of negative refractive power, a second lens group of positive refractive power, a third lens group of positive refractive power; and a fourth lens group of positive refractive power. At least one lens group has an aspheric surface. The ratio of the focal length of the wide-angle projection lens (F) to the focal length of each of the lens groups (F1, F2, F3, and F4) is such that |F1/F|>1.3, F2/F>2, 1<F3/F<2 and 1.5<F4/F<8.

Abstract: An optical system for an endoscope includes a negative lens-group, an aperture diaphragm and a positive lens-group in this order from an object side, wherein the negative lens-group includes a negative first-lens and a negative second-lens in this order from the object side; and wherein the optical system meets conditional expressions (1) and (2): 0.05<H(100)×(nd01?1)/Rf01<0.38??(1) and 0.5<enp/FL<2.5??(2), where: H(100) is a height at which a principal ray with a field angle of incidence of 100 degrees falls on a surface on the object side of the first lens; Rf01 is a curvature radius of the surface on the object side of the first-lens; nd01 is a refractive index of the first-lens; FL is a focal length of an entire system; and enp is a distance between an entrance pupil and the surface on the object side of the first lens.

Abstract: An optical system includes, in order from an enlargement conjugate side to a reduction conjugate side via a largest air gap, a front unit having a negative power, and a rear unit having positive power. The optical system satisfies 1.75<Ndn1<2.05, 0.02<?gFn1?(0.6438?0.001682×? dn1)<0.08, and 2.5<|fn1/F|<5.0, where fnl represents a focal length of a negative lens in the front unit, Ndnl represents a refractive index of a material of the negative lens, ? dn1 represents an Abbe number of the material of the negative lens, ?gFn1 represents a partial dispersion ratio of the material of the negative lens, and F represents a focal length of the optical system.

Abstract: Embodiments are disclosed herein related to the construction of optical elements for an RGB camera system. One disclosed embodiment provides a wide-angle lens construction, comprising a first, negative stage, and a second, positive stage positioned behind the first, negative stage along an optical axis of the lens construction. The second, positive stage further comprises a first positive lens substage, a first negative lens substage, a second positive lens substage, and a second negative lens substage.

Abstract: The present invention provides a projection prime lens including first lens group, a second lens group, and a third lens group arranged in sequence along an optical axis from a screen side to a light modulator side. The first lens group has negative refractive power and includes a first lens with negative refractive power and a second lens with negative refractive power. The second lens group has positive refractive power and includes a third lens with positive refractive power and a fourth lens with positive refractive power The third lens group has positive refractive power and includes a fifth lens with negative refractive power, a sixth lens with positive refractive power, and a seventh lens with positive refractive power. Therefore, the projection prime lens of the present invention has a small size and a good image quality.

Abstract: An optical system includes, in order from an enlargement conjugate side to a reduction conjugate side via a largest air gap, a front unit having a negative power, and a rear unit having positive power. The optical system satisfies 1.75<Ndn1<2.05, 0.02<?gFn1?(0.6438?0.001682×?dn1)<0.08, and 2.5<|fn1/F|<5.0, where fn1 represents a focal length of a negative lens in the front unit, Ndnl represents a refractive index of a material of the negative lens, ?dn1 represents an Abbe number of the material of the negative lens, ?gFn1 represents a partial dispersion ratio of the material of the negative lens, and F represents a focal length of the optical system.

Abstract: A lens system includes a first lens with negative refraction power, and a second lens with positive refraction power. The first lens includes a surface facing the image side having an optical portion. The lens system satisfies the formulas: (1) Y/Z<1.10;(2) G1R1/F1<?3.10; and (3) G2R2/F2>1.49, wherein Y is a distance between an end point of the optical portion and a center point of the optical portion along a direction perpendicular an optical axis, Z is a distance between the end point of the optical portion and the center point of the optical portion along the optical axis, F1 and F2 are the focal lengths of the first and second lenses, respectively, G1R1 and G2R2 respectively denote the radius of curvatures of a surface of the first lens facing the object side and another surface of the second lens facing the image side.

Abstract: A projection lens system includes, in order from the magnified side to the reduced side thereof, a first lens group with negative refractive power, a second lens group with a positive refracting power, and a spatial light modulator. The projection lens system satisfies the following condition: 3.478<BFL/F<3.528. Wherein: BFL is a back focal length of the projection lens system; F is an effective focal length of the projection lens system.

Abstract: A retrofocus wide-angle lens system is provided, wherein the entire the wide-angle lens system is divided at a position that satisfies the following condition (1) between a theoretical front lens group having a negative refractive power, and a theoretical rear lens group having a positive refractive power including the diaphragm, at a minimum focal length, and wherein a flat parallel plate is disposed at the position that satisfies the following condition (1): 1.2<|fF/f|<4.0 . . . (1), wherein fF designates the focal length of the theoretical front lens group having a negative refractive power, and f designates the focal length of the entire the wide-angle lens system.

Abstract: A fixed focus lens system includes a first lens group having a negative refractive power; and a second lens group having a positive refractive power, wherein the first lens group and the second lens group are sequentially arranged from an object side to an image side, and the second lens group includes two lenses having an Abbe's number of 80 or greater.

Abstract: A single focus lens system and a photographing apparatus including the single focus lens system are disclosed. A single focus lens system is provided that includes a first lens group having a negative refractive power, a stop, and a second lens group having a positive refractive power, sequentially arranged in order from an object side, wherein the first lens group comprises first and second air lenses having a negative refractive power, a meniscus shape and a convex surface toward the object side, and the second lens group comprises a lens that has a positive refractive power, is disposed closest to the object side, and has a convex surface toward the object side.

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 includes a first lens that is a negative meniscus lens having a concave surface facing the image side of the imaging lens, a second lens that is a positive lens having a convex surface facing the object side of the imaging lens, a third lens that is a negative lens having a concave surface facing the image side, a fourth lens that is a double-convex lens, a fifth lens that is a negative meniscus lens having a concave surface facing the object side, and a sixth lens that is a negative lens, which are arranged in this order from the object side.

Abstract: A zoom lens includes in order from an object side to an image side and arranged along an optical axis thereof, a first lens unit having a negative refractive power, and a second lens unit having a positive refractive power. A distance between each lens unit changes when zooming from a wide-angle end to a telephoto end. The first lens unit includes a first lens sub-unit including a positive lens element and a negative lens element, and having a negative refractive power, and a second lens sub-unit including a single negative lens element. Focusing is performed by moving the second lens sub-unit in an optical axis direction, a focal length of the second lens sub-unit f1b and a focal length of the entire zoom lens fw at a wide-angle end are suitably set based on predetermined mathematical expressions.

Abstract: An optical imaging system includes a first lens group having a positive or negative optical power, an aperture diaphragm, and a second lens group having a positive optical power arranged in order from an object side. The first lens group includes a first front lens group having at least two negative lenses and a first rear lens group having at least one positive lens with an airspace in-between the first front and rear lens groups. The second lens group includes a second front lens group having first positive and negative lenses, second negative and positive lenses arranged in order from the object side, and a second rear lens group including at least one aspherical lens. When focusing on an object in a close range from infinity, the second lens group moves to the object side while an interval between the second front and rear lens groups are shortened.

Abstract: A wide-angle projection optical system includes a first lens set with positive power, an aperture stop, a second lens set with positive power, a third lens set with negative power, and a negative power reflecting mirror. The first lens set provides optical characteristics to match with a light beam coming from the object side. The second lens set is arranged behind the aperture stop to converge the light beam. The third lens set is configured to diverge the light to enlarge a full field angle. The negative power reflecting mirror is configured to further enlarge the full field angle and correct image distortion. The first lens set, the second lens set, the third lens set and the reflecting mirror have a common optical axis. The optical axis is shifted with respect to a center of a micro display.

Abstract: A lens system includes, in order from the subject side to the image side of thereof, a first lens group of negative refractive power, a second lends group of positive refractive power, and an image plane. The first lens group includes a first spherical lens, a second spherical lens, and a third spherical lens arranged in this order from the subject side to the image side of the lens system. The first spherical lens includes a first subject surface and a first image surface. The lens system satisfies the following formula: 8.9<D/F0<9.9, wherein, D is the distance between an apex point of the first subject surface and the image plane along the optical axis of the lens system, F0 is the effective focal length of the lens system.

Abstract: A super-wide-angle lens system for imaging an object on an imaging surface, 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 spherical lens with negative refraction power, a second spherical lens with negative refraction power, and a third spherical lens with positive refraction power. The first lens has a first surface facing the object side of the first lens group. The second lens group includes a fourth spherical lens with positive refraction power and a fifth spherical lens with negative refraction power. The system satisfies the formulas: 0.01<D/|FG1|<1, and 2<D/FG2<4, where D is the distance from the first surface to the imaging surface, FG1 is the effective focal length of the first lens group, and FG2 is the effective focal length of the second lens group.

Abstract: The present disclosure relates to a projection lens system for a projector having a spatial light modulator (SLM). The projection lens system includes, in order from the magnified end to the minified end thereof, a first lens group with negative refraction power, a second lens group with positive refraction power, and a third lens group with positive refraction power. The projection lens system satisfies the following formulas: 3<TT/f<3.6, and 0.48<BFL/f; wherein, TT is the overall length of the projection lens system; f is an effective focal length of the projection lens system; BFL is the back focal length of the projection lens system, the back focal length is equal to the distance between the third lens group and the SLM.

Abstract: An objective lens includes, in order from an object side, a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power, wherein the front group includes, in order from the object side, a first lens which is a negative meniscus lens with a convex surface turned to the object side and a second lens which is a negative lens with a concave surface turned to the object side; the rear group includes, in order from the object side, a positive third lens and a fourth lens made up of a positive lens and a negative lens cemented together, and the objective lens satisfies conditional expression (1) below: ?0.8<f—F/f—R<?0.3 ??(1), where f_F is a focal length of the front group, and f_R is a focal length of the rear group.

Abstract: An imaging lens system includes three lens groups having four lenses including a first lens, a second lens, a third lens, and a fourth lens arranged in order from an object side, and an aperture stop arranged between the first lens and the second lens. The second lens and the third lens are joined each other. The first lens is a negative meniscus lens having a convex surface at an object side. The second lens is a positive lens having a convex surface having a large curvature at an image side. The third lens is a negative lens having a concave surface having a large curvature at an object side. The fourth lens is a positive lens having a convex surface having a large curvature at an image side. The following conditions are satisfied: 1.4<|f1/F|<2.2 0.4<|f1/f23|<1.6 where F is a focal length of the entire imaging lens system, f1 is a focal length of the first lens, and f23 is a combined focal length of the second lens and the third lens which are joined each other.

Abstract: A wide-angle lens consists of, in order from an object, a front lens group GF consisting of a first front lens group GF1 that consists of a negative meniscus lens L11 having a concave surface facing an image, a second front lens group GF2 that consists of a negative lens L12 having a concave surface facing the image, and a third front lens group GF3 that has a convex surface facing the object and has positive refractive power; and a rear lens group GB consisting of a first rear lens group GB1 that consists of a cemented positive lens constructed by a negative lens L14 and a positive lens L15, and a second rear lens group GB2 having positive refractive power; thereby providing a wide-angle lens having a wide angle of view, well corrected aberrations, less ghost images capable of coping with wide luminance difference, and an imaging apparatus equipped therewith.

Abstract: A projection lens disposed between an enlarged side and a reduced side and including a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having positive refractive power, and an optical element disposed between the second and the third lens groups is provided. The first lens group includes a first and a second lens sequentially arranged from the enlarged side to the reduced side and respectively having a positive and a negative refractive power. The second lens group between the first lens group and the reduced side includes a third, a fourth, a fifth, and a sixth lens sequentially arranged from the enlarged side to the reduced side. The fifth and the sixth lens respectively have a positive refractive power. The third lens group disposed between the second lens group and the reduced side includes a seventh lens.

Abstract: An imaging lens includes a first group having a positive or negative refractive power, a second group having a positive refractive power, a third group having a positive or negative refractive power, which are sequentially arranged from the object side of the imaging lens. The first group includes an aperture stop, and the second group includes a positive lens, and a cemented lens of a positive lens and a negative lens. The third group is composed of a cemented lens of a positive lens and a negative lens, and the following formula (1) is satisfied: 0.5?f2/f?1.2??(1), where f: focal length of the entire system of the imaging lens, and f2: focal length of the second group.

Abstract: An optical system WL has, in order from an object, a first lens group G1 having negative refractive power and a second lens group G2 having positive refractive power, wherein the first lens group G1 is fixed and the second lens group G2 moves upon focusing from an object at infinity to an object at a finite distance, and the second lens group G2 is formed of a front group G2a located closer to the object than an aperture stop S disposed in the second lens group G2, and a rear group G2b located closer to an image than the aperture stop S.

Abstract: A photographic lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a stop, and a third lens unit having a positive refractive power. In the photographic lens, the third lens unit moves towards the object side while the second lens unit moves towards the image side during focusing from an infinitely distant object to a closest distance object. In addition, in the photographic lens, an image forming magnification of the second lens unit during focusing on a closest distance object is appropriately set.

Abstract: Large aperture optical systems that are extremely well corrected over a large flat field and over a large spectral range are disclosed. Breathing and aberration variation during focusing are optionally controlled by moving at least two groups of lens elements independently. Aberration correction in general is aided by allowing the working distance to become short relative to the format diagonal. Field curvature is largely corrected by a steeply curved concave surface relatively close to the image plane. This allows the main collective elements to be made of low-index anomalous dispersion materials in order to correct secondary spectrum. In wide-angle example embodiments, distortion may be controlled with an aspheric surface near the front of the lens.

Abstract: A super wide angle lens is a super wide angle lens which is of high-resolution and whose size, weight and cost can be reduced. It employs a four-group five-element constitution in which in the order from an object side, a meniscus single lens having a negative power, a single lens having a negative power, a single lens having a positive power, and a cemented lens having a positive power are included. The lenses excluding the meniscus single lens are plastic lenses and seven lens surfaces, that are a third surface, a fourth surface, a fifth surface, a sixth surface, a eighth surface, a ninth surface and a tenth surface, are aspheric.

Abstract: Provided is a high-performance objective optical system which is compatible with a high-pixel-count image acquisition device, in which focusing can be achieved according to a change in object point distance and which has sufficient depth of field at the individual object point distances. Provided is an objective optical system (1) including, in order from an object side, a first group (G1), a second group (G2), and a third group (G3), in which the first group (G1) includes, in order from the object side, a plano-concave lens (L1) and a meniscus lens (L2) whose convex surface is towards an image side and in which the second group (G2) includes a positive meniscus lens whose convex surface is towards the object side and moves in the direction of an optical axis to perform focusing.

Abstract: A retrofocus wide-angle lens system is provided, wherein the entire the wide-angle lens system is divided at a position that satisfies the following condition (1) between a theoretical front lens group having a negative refractive power, and a theoretical rear lens group having a positive refractive power including the diaphragm, at a minimum focal length, and wherein a flat parallel plate is disposed at the position that satisfies the following condition (1): 1.2<|fF/f|<4.0??(1), wherein fF designates the focal length of the theoretical front lens group having a negative refractive power, and f designates the focal length of the entire the wide-angle lens system.

Abstract: Providing a wide-angle lens having high optical performance, an optical apparatus using thereof, and a method for focusing the wide-angle lens. The lens including, in order from an object, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, and a third lens group G3 having positive refractive power. Upon varying focusing from an object locating at infinity to an object locating at close distance, the first lens group G1 is fixed, and the second lens group G2 and the third lens group G3 are moved to the object side. The second lens group G2 includes a negative lens component L21 to the most object side, and a given conditional expression is satisfied.

Abstract: A center lens for collecting light in a center range and left/right lenses for collecting light in left/right ranges are supported in one plane to form center and left/right unit images. A microprocessor combines the unit images into a wide-angle image. The left/right optical lenses are placed on left-right direction line parallel to the wide-angle direction, while the center lens is placed distant from the left/right lenses above the direction line. Prisms are placed in front of the left/right lenses, and a toroidal lens to vertically modify the light path for light convergence onto each lens is placed in front of the prisms. The toroidal lens has a vertically curved surface having an axis coinciding with the direction line, and a horizontally cured surface having an axis coinciding with a vertical line passing through the center lens. This device can obtain a wide-angle image with a vertically large picture angle.

Abstract: A projection lens includes a first lens group with a negative refractive power, a second lens group with a negative refractive power, and a third lens group with a positive refractive power, wherein the second lens group is disposed between the first lens group and the third lens group. The first lens group includes an aspheric lens. The second lens group includes a first lens and a second lens. The third lens group includes a third lens, a forth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens.

Abstract: A projection optical system including a first optical system configured to form a second image conjugate to a first image and a second optical system configured to include a reflective optical element which reflects light from the second image and to project a third image conjugate to the second image onto a projection surface is provided, wherein the first optical system has a Petzval sum with a sign opposite to a sign of a Petzval sum of the second optical system.

Abstract: A fixed-focus lens adapted to be disposed between a magnified side and a reduced side is provided. The fixed-focus lens includes a first lens group, a second lens group, and a third lens group. The first lens group disposed between the magnified side and the reduced side includes three lenses and has a negative refractive power. The second lens group disposed between the first lens group and the reduced side includes five lenses and has a positive refractive power. The third lens group disposed between the second lens group and the reduced side includes five lenses and has a positive refractive power. The fixed-focus lens satisfies |F1/F|<1.35, 3.5<|F2/F|<4.5, and 4<|F3/F|<5, wherein F1 is the effective focal length (EFL) of the first lens group, F2 is the EFL of the second lens group, F3 is the EFL of the third lens group, and F is the EFL of the fixed-focus lens.

Abstract: An optical system includes a first lens unit, an aperture stop, and a second lens unit having a positive refractive power. In the optical system, the first lens unit includes at least one positive lens made of a material whose Abbe number (?dGP) and relative partial dispersion (?gFGP) satisfy a predetermined condition.

Abstract: A ultra-wide angle objective lens comprising a first group having a first lens element having a convex object surface facing the object and a concave image surface facing the image plane, and a second aspheric lens element, the second aspheric lens element having a varying power that is negative at its vertex; and that increases positively with radial distance from the vertex. A second group has at least one lens element and a positive power. A third group has at least a first and a second lens element and a positive power. The ratio of the total track to the focal length satisfies the condition that TT/fo=<33 and the image height on a focal plane is h(?)>f*?, where h(?) is the image height formed by an off-axis chief ray having a field angle ?, and f is the effective focal length of the lens.

Abstract: A wide-angle lens consists of, in order from an object, a front lens group GF consisting of a first front lens group GF1 that consists of a negative meniscus lens L11 having a concave surface facing an image, a second front lens group GF2 that consists of a negative lens L12 having a concave surface facing the image, and a third front lens group GF3 that has a convex surface facing the object and has positive refractive power; and a rear lens group GB consisting of a first rear lens group GB1 that consists of a cemented positive lens constructed by a negative lens L14 and a positive lens L15, and a second rear lens group GB2 having positive refractive power; thereby providing a wide-angle lens having a wide angle of view, well corrected aberrations, less ghost images capable of coping with wide luminance difference, and an imaging apparatus equipped therewith.

Abstract: An endoscope objective lens system design is disclosed, generally comprising a first lens group having overall negative refractive power, a second lens group having overall positive refractive power, and an aperture diaphragm disposed between the first and second lens groups wherein the first lens group includes a plano-concave lens with its concave surface facing the objective end of the endoscope.

Abstract: A fixed-focus lens including a first lens group and a second lens group is provided. The first lens group is disposed between a magnified side and a reduced side and includes a first lens and a second lens arranged in sequence from the magnified side to the reduced side. The refractive powers of both the first lens and the second lens are negative, and the first lens is an aspheric lens. The second lens group is disposed between the first lens group and the reduced side and includes a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged in sequence from the magnified side to the reduced side. The refractive powers of the seven lenses from the third lens to the ninth lens are respectively positive, negative, positive, negative, positive, negative, and positive in sequence.

Abstract: A wide-angle image pick-up lens system includes a first lens group with negative refracting power and a second lens group with positive refracting power. The first lens group and the second lens group are aligned in order from an object side to an image side. The first lens group and the second lens group satisfy the following conditions: ?0.15<f10/f12<?0.05, 0.3<f10/f14<0.8, wherein f10 is a focal length system, f12 is an effective focal length of the first lens group, and f14 is an effective focal length of the second lens group. The first lens group includes a third lens with positive refracting power. A refractive index of the third lens is above of 1.85.