Abstract: A zoom lens includes, in order from an object side to an image side, first to fifth lens units respectively having positive, negative, positive, negative, and positive refractive powers. During zooming from a wide-angle end to a telephoto end, each of the lens units moves in such a way that a distance between the first and second lens units increases, a distance between the second and third lens units decreases, a distance between the third and fourth lens units increases, and a distance between the fourth and fifth lens units increases. The distances D34w and D34t between the third and fourth lens units, the distances D45w and D45t between the fourth and fifth lens units, focal lengths fw and ft of the entire zoom lens, and focal lengths f1 and f4 of the first and fourth lens units are appropriately set.

Abstract: A zoom lens system comprising a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit, wherein the second lens unit is composed of an object-side second lens unit and an image-side second lens unit, the object-side second lens unit has positive optical power, an aperture diaphragm is located between the object-side second lens unit and the image-side second lens unit, and the conditions: ?0.5<f2O/f2I<1.0 and 0.12<d2O/fW<0.35 (f2O: a composite focal length of the object-side second lens unit, f2I: a composite focal length of the image-side second lens unit, d2O: an optical axial distance from a most object side lens surface of the object-side second lens unit to the aperture diaphragm, fW: a focal length of the entire system at a wide-angle limit) are satisfied.

Abstract: There is provided an eyepiece optical system including a lens, a surface nearest to an observer side of the lens disposed nearest to the observer side being formed in a convex shape on the observer side, and the eyepiece optical system satisfying a conditional expression (1) |RL/DH|<1.7, where RL is a radius of curvature of the surface nearest to the observer side, and DH is a shortest distance in a radial direction from an optical axis to an edge surface of the lens nearest to the observer side.

Abstract: An annular inclined surface is formed on an edge portion of a first plastic lens in such a manner that the inclined surface surrounds a concave surface formed in a second surface of the first plastic lens. The inclined surface reflects unwanted light reflected by the concave surface so as to prevent the unwanted light from passing through the non-shading portion of the edge portion outside the effective area of a lens portion and then being reflected on an imaging area. This can suppress ghosting and flare due to the reflection of the unwanted light on the imaging surface.

Abstract: An imaging optical system, includes: in the order from an object side to an image plane side, a first lens group having a first lens which is formed as a negative lens; a second lens group having a second lens which is formed as a plano-concave lens, a third lens which is formed as a negative meniscus lens, and a fourth lens which is formed as a biconvex lens; an aperture stop; a third lens group having a fifth lens which is formed as a biconvex lens, and a sixth lens which is formed as a biconcave lens; and a fourth lens group having a seventh lens which is formed as a negative meniscus lens.

Abstract: A zoom lens includes sequentially from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power. The zoom lens satisfies given conditions to implement a compact, wide angle, large aperture ratio zoom lens having excellent optical performance and compatible with solid state image sensors capable of recording full high vision images.

Abstract: A wide angle optical system including a first lens group of negative refractive power and a second lens group of positive refractive power arranged in the above-mentioned order from the object side. The second lens group includes a cemented doublet SU21; an aperture diaphragm; a lens SU22; and a biconvex lens L25 arranged in the above-mentioned order from the object side, and largest ones of air spaces on the axis being front and rear spaces of the aperture diaphragm except the back focal length. The wide angle optical system is divided into the first lens group and the second lens group at the second largest air space operating as a boundary.

Abstract: An imaging lens includes a first lens group having negative refractive power; a stop; and a second lens group having positive refractive power, arranged in the order from the object side to the image plane side. The first lens group includes a first lens having a strong concave surface facing the image plane side and negative refractive power; and a second lens having negative refractive power and a biconcave lens shape near the optical axis. The second lens group includes a third lens having a biconvex shape; and a lens group that is composed of a lens having positive refractive power and a lens having negative refractive power, and has negative refractive power as a whole. The first lens group has a focal length F1 and the second lens group has a focal length F2 so that the following conditional expression is satisfied: ?1.0<F1/F2<?0.

Abstract: A lens module comprises a barrel, a first lens, a first spacer ring, a second lens having an effective aperture A, a second spacer ring having an inner diameter B, and a third lens having an effective aperture C. The first lens, the first spacer ring, the second lens, the second spacer ring, the third lens and the infrared cut-off filter are coaxially assembled within the barrel, along an axial direction of the barrel in that order. The first spacer ring is sandwiched between the first lens and the second lens, the second spacer ring is sandwiched and located between the second lens and the third lens. The inner diameter B of the second spacer ring is smaller than the effective aperture C of the third lens and larger than the effective aperture A of the second lens, so as to satisfy the condition of C>B>A.

Abstract: An inner focus lens, in order from an object side to an image side, comprising: a first lens unit having positive optical power; a second lens unit having negative optical power; and a third lens unit having positive optical power, wherein the second lens unit is moved along an optical axis so that focusing from an infinite-distance object side to a short-distance object side is achieved, the first lens unit includes a bi-convex air lens, and the following conditions: 0.65<|f2/f|<5.00 and 0.5<f23/f1<9.0 (f2: a focal length of the second lens unit, f and f23: a focal length of the entire system and a composite focal length of the second and third lens units in an infinity in-focus condition, f1: a focal length of the first lens unit) are satisfied; an interchangeable lens apparatus; and a camera system are provided.

Abstract: An image capturing 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 and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power has a concave image-side surface. The third lens element with positive refractive power has a convex image-side surface. The fourth lens element has positive refractive power. The fifth lens element with refractive power is made of plastic material and has a concave image-side surface. At least one inflection point is formed on at least one of the object-side and image-side surfaces of the fifth lens element. The surfaces of the third lens element, the fourth lens element and the fifth lens element are aspheric.

Abstract: Disclosed herein is an imaging lens unit, including: a first lens having a positive (+) power; a second lens having a negative (?) power; a third lens having power; a fourth lens having a negative (?) power; and a fifth lens having a negative (?) power, wherein the first lens, the second lens, the third lens, the fourth lens, and fifth lens are arranged in order from an object to be formed as an image, and the fourth lens is convex toward an image side.

Abstract: An imaging lens substantially consists of a negative first lens group and a positive second lens group in this order from the object side. The first lens group substantially consists of only a first lens, which is one biconcave lens. The second lens group substantially consists of, in the following order from the object side: a cemented lens, which is formed by bonding a positive lens and a negative lens, in this order from the object side, and which has a positive refractive power as a whole; an aperture stop; a positive lens; and a negative lens. The imaging lens is configured to satisfy the conditional expressions (1a): 0<f23/f<2.5 and (2a): 0<f45/f<6 at the same time.

Abstract: An imaging lens substantially consists of a negative first lens group and a positive second lens group in this order from the object side. The first lens group substantially consists of merely a first lens, which is one negative lens. The second lens group substantially consists of, in the following order from the object side: a cemented lens, which is formed by bonding a positive lens, and a negative lens, in this order from the object side, and which has a positive refractive power as a whole; an aperture stop; a positive lens; and a negative lens. The imaging lens is configured to satisfy the conditional expression (1a): ?2.3<f1/fg2<?0.45, where f1 represents the focal length of the first lens, and fg2 represents the focal length of the second lens group.

Abstract: An imaging lens substantially consists of a negative first lens group and a positive second lens group in this order from the object side. The first lens group substantially consists of only a first lens, which is one biconcave lens. The second lens group substantially consists of, in the following order from the object side: a cemented lens, which is formed by bonding a second lens, i.e., a biconvex lens, and a third lens, i.e., a negative meniscus lens, in this order from the object side, and which has a positive refractive power as a whole; an aperture stop; and a cemented lens that is formed by bonding a fourth lens, i.e., a biconvex lens and a fifth lens, i.e., a negative meniscus lens in this order from the object side and that has a positive refractive power as a whole.

Abstract: An imaging lens includes in order from an object side a first lens group including a positive refractive power and a second lens group having a negative refractive power, the first lens group and the second lens group including a widest air space therebetween, the first lens group including in order from the object side a negative first lens having a concave face on the object side, a positive second lens having a convex face on both sides, an aperture stop, a negative third lens having a concave face on the object side, a positive fourth lens having a convex face on an image side and a positive fifth lens having a convex face on the image side, and the second lens group including a negative meniscus sixth lens having a concave face on the object side.

Abstract: An imaging lens including seven or fewer lenses which constitute an entire system of an optical system comprising, in order from an object side to an imaging side: a first lens group having a positive refractive power; a second lens group having a positive refractive power; and a third lens group having a negative refractive power, wherein the first lens group includes a lens having a negative refractive power and a lens having a positive refractive power, an aperture stop being disposed in the first lens group, the second lens group includes one lens having a negative refractive power and one lens having a positive refractive power, and the third lens group including one lens having a negative refractive power and a concave surface on the object side.

Abstract: Low ghosting wide-angle lens designs are presented. The dimensions and materials are selected such that the lens has a field of view of at least 145 degrees, f# of 2.2-2.9 and all secondary images of an object imaged on the image plane are focused such that they fall either outside of the image plane thus having a relative intensity that is less than 10?4 times the intensity of the primary image. In one embodiment a set of conditional expressions are all met. In another embodiment the conditional expressions are all met and the conditional expressions related to the physical size of the lens is narrowed. In another embodiment five and seven element designs are produced.

Abstract: An imaging lens provided with a negative first lens group and a positive second lens group arranged in order from the object side. The first lens group is composed of a first group first lens which is a biconcave negative single lens, and the second lens group is composed of a positive second group first lens, an aperture stop, a positive second group second lens, and a negative second group third lens arranged in order from the object side, in which the second group second lens and the second group third lens are cemented together to form a cemented lens. When f1 and f2 are taken as the focal lengths of the first group first lens and the second group first lens respectively, the imaging lens satisfies a conditional expression (4a?): 0.62<|f1/f2|<0.82.

Abstract: An image forming optical system of four lenses includes in order from an object side, a first lens having a positive refractive power, which is a biconvex lens, a second lens having a negative refractive power, of which, an image-side surface is a concave surface, a third lens having a positive refractive power, which is meniscus-shaped with a concave surface directed toward the object side, a fourth lens having a negative refractive power, of which, an image-side surface is a concave surface, and an aperture stop which is disposed nearest to the object side. The image forming optical system satisfies predetermined conditional expressions.

Abstract: The diameter of an endoscope insertion portion is reduced, and a wide field angle of an endoscope insertion portion is obtained. An endoscope objective optical system includes, from an object side, a first lens formed of a plano-concave lens having a concave surface facing an image side, a second lens formed of a plano-concave lens having a concave surface facing the object side, an aperture stop, and a third lens formed of a plano-convex lens having a plane surface facing the object side, and satisfies 0.7?|fab/f|0.9 1.7?|fe/fab|?2 2?fb/fa?4 where f: focal length of the entire system; fa: focal length of the first lens; fb: focal length of the second lens; fe: represents focal length of the third lens; fab: combined focal length from the first lens to the second lens.

Abstract: A three-dimensional imaging system uses a single primary optical lens along with various configurations of apertures, refocusing facilities, and the like to obtain three offset optical channels each of which can be separately captured with an optical sensor.

Abstract: A three-dimensional imaging system uses a single primary optical lens along with various configurations of apertures, refocusing facilities, and the like to obtain three offset optical channels each of which can be separately captured with an optical sensor.

Abstract: Provided are a lens assembly and an optical system including the same. The lens assembly may include a first lens having a groove region, a second lens having an insertion region that is inserted into the groove region, and a light blocking member between the first lens and the second lens. The light blocking member may be disposed between a first surface portion of the first lens and a second surface portion of the second lens, and the light blocking member may be separated from at least one of the first surface portion and the second surface portion. The lens assembly may further include at least one additional lens. The lens assembly may be applied to various optical systems.

Abstract: An imaging optical system including, from the object side to the image side, a first lens group having positive refracting power, an aperture stop, and a second lens group having positive power, in which the first lens group consists of three lens subgroups, having positive, negative and positive refracting powers, respectively, from the object side to the image side, with satisfaction of the following: 4<(LTL+fB)/fB<15??(1) 0.3<D12/IH<4??(2) where fB is an on-axis distance, from an image side-surface in the second lens group to an image plane upon focusing at infinity, LTL is an on-axis distance from an object side-surface in the first lens group to the image side-surface in the second lens group, D12 is an on-axis length from an image side-surface in the first lens group to an object side-surface in the second lens group upon focusing at infinity, and IH is a maximum image height.

Abstract: A zoom lens system, in order from an object side to an image side, comprising a positive first lens unit, a negative second lens unit, a positive third lens unit, and a positive fourth lens unit, wherein the first lens unit is composed of a cemented lens element of one object side negative lens element and one image side positive lens element, the fourth lens unit is composed of one lens element, in zooming, the first to fourth lens units are individually moved along an optical axis so that air spaces between the respective lens units vary for magnification change, and the conditions: vdL12<43.50 and fT/fW?6.0 (vdL12: an Abbe number of the positive lens element in the first lens unit, fT and fW: focal lengths of the entire system at a telephoto limit and a wide-angle limit) are satisfied; an imaging device; and a camera.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit of a negative refractive power, a second lens unit of a positive refractive power, and a third lens unit of a positive refractive power, an interval between the first lens unit and the second lens unit and an interval between the second lens unit and the third lens unit being configured to change in zooming from a wide angle end to a telephoto end. The first lens unit includes, in order from the object side to the image side, a negative lens and a positive lens. The predetermined conditions are satisfied.

Abstract: An object-side lens group has different power factors between the vertical and horizontal directions of a liquid crystal panel, and a projection system as a whole therefore has different focal lengths between the vertical and horizontal directions and hence different magnification factors between the vertical and horizontal directions, whereby the aspect ratio of an image on the liquid crystal panel can be set at a value different from the aspect ratio of an image projected on a screen. That is, the projection system can convert the aspect ratio, which is the ratio of the width to the height of an image. When the distance between a diaphragm and an extreme end surface of the object-side lens group on the screen side satisfies a predetermined condition, at least a certain degree of telecentricity can be provided both in the vertical and horizontal directions.

Abstract: Ring-field, catoptric and catadioptric, unit-magnification, projection optical systems having non-concentric optical surfaces are disclosed. Each system has a system axis with object and image planes on opposite sides of the system axis. The non-concentric surfaces allow for working distances of the object and image planes in excess of 100 millimeters to be achieved, with a ring-field width sufficient to allow a rectangular object-field having a long dimension in excess of 100 mm to be projected.

Abstract: An inner focus lens system includes from the object side, a first lens unit having a positive refractive power, an aperture stop, a second lens unit having a positive refractive power, and a third lens unit. The first lens unit includes a plurality of negative lenses and at least one positive lens, the lens located closest to the object side is a negative lens. The second lens unit includes at least one negative lens and at least one positive lens, and moves toward the object side for focusing from an infinite object distance to a close object distance such that the distance between the second lens unit and the aperture stop decreases and that the distance between the second lens unit and the third lens unit increases. The lens system satisfies the following conditions: 1<f1/f 14 (1), and 0.8<f23/f2<3 (2).

Abstract: An image 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 and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element with refractive power is made of plastic material, and has at least one surface being aspheric. The fourth lens element with refractive power is made of plastic material, and has a concave object-side surface and a convex image-side surface, wherein at least one surface of the fourth lens element is aspheric. The fifth lens element with positive refractive power is made of plastic material, and has a convex object-side surface and a convex image-side surface, wherein at least one surface of the fifth lens element is aspheric.

Abstract: This invention provides an optical image capturing lens system comprising: a negative first lens element having a convex object-side surface and a concave image-side surface at the paraxial region; a positive second lens element; a negative third lens element; a positive fourth lens element having a convex image-side surface at the paraxial region; and a negative plastic fifth lens element having a convex object-side surface at the paraxial region as well as a concave at the paraxial region and convex at the peripheral region image-side surface, at least one of the object-side and image-side surfaces being aspheric. The optical image capturing lens system of the present invention effectively increases the angle of view to a proper range and suppresses the distortion. In addition, the present invention has a tighter arrangement of the lens elements and a smaller back focal length, and therefore is more appropriate for the compact device.

Abstract: An optical image 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 and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface and a convex image-side surface. The second lens element with refractive power has a concave object-side surface and a convex image-side surface. The third lens element with refractive power has two surfaces being aspheric. The fourth lens element with positive refractive power has a convex image-side surface, wherein the surfaces of the fourth lens element are aspheric. The fifth lens element with negative refractive power has a concave image-side surface, wherein the surfaces of the fifth lens element are aspheric, and the fifth lens element has inflection points on at least one of the surfaces thereof.

Abstract: The present invention relates to optical unit comprising, seen in the direction from the object side to the imaging surface, a first substrate, a first lens, a second lens and a second substrate, characterised in that the distance [(vertex first lens) and (vertex second lens)] is 250-650 pm. Such an optical unit is used, inter alia, in image processing units, such as cameras. It is an object of the present invention to provide an optical unit in which the desired dimensional precision of the lens system can be accomplished without this leading to an undesirable increase of the optical unit's dimensions.

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 zoom lens system comprising a plurality of movable lens units which individually move along an optical axis at the time of zooming from a wide-angle limit to a telephoto limit during image taking, wherein at least two of the movable lens units are focusing lens units which move along the optical axis at the time of focusing from an infinity in-focus condition to a close-object in-focus condition in at least one zooming position, and among the focusing lens units, a lens unit having the absolute value, which is not the greatest absolute value, of a wobbling value at a wide-angle limit is a wobbling lens unit which senses a moving direction of the focusing lens units at the time of focusing by wobbling itself in a direction along the optical axis; an interchangeable lens apparatus; and a camera system are provided.

Abstract: An image capturing optical system 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 and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element with negative refractive power has a concave object-side surface and a convex image-side surface. The third lens element has refractive power, wherein the surfaces of the third lens element are aspheric. The fourth lens element has positive refractive power, wherein the surfaces of the fourth lens element are aspheric. The fifth lens element with refractive power is made of plastic material, and has a concave image-side surface, wherein the surfaces of the fifth lens element are aspheric, and the fifth lens element has inflection points formed on at least one of the surfaces thereof.

Abstract: An imaging lens, includes: in order from an object side to an image side, a first negative lens group including a negative lens a concave surface of which faces the image side; a second positive lens group including a negative lens a concave surface of which faces the object side, and a positive lens, or a cemented lens entirely having a positive refractive power in order from the object side to the image side; an aperture; a third positive lens group including a cemented lens of a biconvex lens and a biconcave lens from the object side; and a fourth lens group having a weakest refractive power among all of the lens groups and including a single lens, or a cemented lens, a surface on the object side of which is concave and a surface on the image side of which is convex.

Abstract: A compact imaging optical system having a light-weight focusing lens is provided. The imaging optical system includes, in order from an object side to an image side, a front unit in which a negative lens element is arranged closest to the object side, an aperture diaphragm, and a rear unit having positive optical power. In focusing from an infinite distance object to a short distance object, the negative lens element arranged closest to the object side and the aperture diaphragm are fixed with respect to an image surface, and a part of lens elements included in the front unit or the rear unit moves along an optical axis. The imaging optical system satisfies the following condition (1): 0.9<R/f<2.0 (R: an average between an image side curvature radius of the negative lens element arranged closest to the object side, and an image side curvature radius of a second negative lens element from the object side among all the negative lens elements; f: a focal length of the entire system).

Abstract: A zoom lens includes a first lens unit of a positive refractive power, a second lens unit of a negative refractive power, a third lens unit of a positive refractive power, and a fourth lens unit of a positive refractive power, wherein the first lens unit does not move for zooming, at least the second and fourth lens units are moved during zooming, the first lens unit includes at least one positive lens, and an Abbe number and a relative partial dispersion of a material of the positive lens, an average refractive index of materials of negative lenses included in the second lens unit, a movement amount of the second lens unit for zooming from a wide-angle end to a telephoto end, a focal length of the second lens unit, and a focal length of the entire zoom lens at the telephoto end are appropriately set.

Abstract: The invention relates to an optical unit comprising. The present invention further relates to the use of such an optical unit. Such an optical unit comprises, seen in a direction from the object side to the imaging surface, a first substrate, a first lens element, a second lens element and a second substrate, characterised in that the first substrate includes a diaphragm function.

Abstract: An imaging lens includes negative first lens having a concave image-side surface, positive second lens having a convex object-side surface in a paraxial region, an aperture stop, and positive third lens having a convex image-side surface in the paraxial region, which are arranged in this order from an object side. The Abbe numbers of materials constituting the first lens and the third lens for d-line are greater than or equal to 40. The Abbe number of a material constituting the second lens for d-line is less than or equal to 40. When the focal length of an entire system is f, and the center thickness of the second lens is D3, and the focal length of the first lens is f1, the following formulas (1?) and (2) are satisfied: 1.7<D3/f<2.9; and??(1?) ?5.0<f1/f<?1.8.

Abstract: It has conventionally been difficult to reduce the size of a fast lens system having an F number of about 1.4 to 2.4. In a lens system of the present invention, a positive lens element is disposed closest to an object side. A diaphragm is disposed in a widest air space in the lens system. The lens system of the present invention satisfies the following conditions: 0.05<L_1/L—TH<0.21 1.5<L—TH/Y<8 where L_1 is an interval from a lens surface located closest to the object side to a lens surface located on the object side relative to the diaphragm; L_TH is an interval from the lens surface located closest to the object side to a lens surface located closest to an image side; and Y is a maximum image height.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side, wherein upon zooming from the short focal length extremity to the long focal length extremity, the distance between the first lens group and the second lens group decreases, and the distance between the second lens group and the third lens group increases. The second lens group includes a positive first sub-lens group and a negative second sub-lens group, in that order from the object side. The second sub-lens group is a negative single lens element serving as an image-stabilizer lens group which moves in directions orthogonal to the optical axis to change the imaging position to correct image shake.

Abstract: A photographing optical lens system 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 and a fifth lens element. The first lens element with positive refractive power has a convex object-side surface. The second lens element has negative refractive power. The third lens element has refractive power. The fourth lens element with positive refractive power has a convex image-side surface. The fifth lens element with refractive power has a concave image-side surface, wherein an object-side surface and the image-side surface of the fifth lens element are aspheric, and the fifth 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: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side, wherein upon zooming from the short to long focal length extremities, the distance between the first lens group and the second lens group decreases, and the distance between the second lens group and the third lens group increases. The second lens group includes a positive first sub-lens group and a negative second sub-lens group, in that order from the object side. In at least part of the zooming range of the zoom lens system, the second sub-lens group and the third lens group each serves as a focusing lens group that is moved along the optical axis during a focusing operation.

Abstract: Provided are a wide angle optical system having better optical performance, low in cost, and compact in size, an imaging lens device having the wide angle optical system, a monitor camera, and a digital apparatus. The wide angle optical system (1) has, in order from the object side to the image side, a first lens (11) having a negative optical power, a second lens (12) having a negative optical power, a third lens (13) having a positive optical power, an aperture (15), and a fourth lens (14) having a positive optical power. The wide angle optical system satisfies the conditional expression of 3<f34/f<10, where f34 is the composite focal length of the third and fourth lenses (13, 14) and f is the focal length of the entire system.

Abstract: A zoom lens including first to fifth lens units in order from an object side toward an image. The refractive powers of the first to the fifth lens units are positive, negative, positive, negative and positive, respectively. The distance between the first and the second lens units is increased at the time of zooming from the wide angle end to the telephoto end, and the distance between the second and the third lens unit is decreased at the time of zooming from the wide angle end to the telephoto end. The first lens unit and the fourth lens unit are fixed for the zooming. When M2 and M3 are the amounts of movement of the second lens unit and the third lens unit at the time of zooming from the wide angle end to the telephoto end, respectively, the conditional expression; 0.2<|M2/M3|<5.0 is satisfied.

Abstract: A lens barrel assembly has a first groove formed in a stationary barrel. A second groove is formed in a rotatable barrel. A diaphragm control plate portion is disposed between an inner surface of the rotatable barrel and an iris diaphragm device in a rotatable manner in a circumferential direction, has an end portion connected to a driving ring. An engaging groove is formed in the diaphragm control plate portion to extend along the optical axis. An operable aperture ring is disposed outside the stationary barrel. A pin device has first and second end portions, the first end portion being secured fixedly to the aperture ring, the second end portion being inserted through the first and second grooves and the engaging groove, for operating upon rotation of the aperture ring to cause the engaging groove to rotate the diaphragm control plate portion to actuate the driving ring.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a negative refractive power and a second lens unit having a positive refractive power. A distance between the first lens unit and the second lens unit varies during zooming. The first lens unit includes, in order from the object side to the image side, a negative lens and a positive lens of which an object-side lens surface has a convex shape. An Abbe number of a material of the positive lens of the first lens unit, a focal length of the first lens unit, a distance between an image-side lens surface of the first lens unit and an object-side lens surface of the second lens unit at a telephoto end, and focal lengths of the entire zoom lens at a wide-angle end and the telephoto end are appropriately set.