Abstract: A wide-angle objective in accordance with the invention comprises, in an order from an object-side end to an image-side end, a front group of total positive refractive power having at least four lenses; a middle group of total positive refractive power having at least three lenses; and a rear group of total positive refractive power having at least three lenses, wherein the quotient of the focal length of the front group and the total focal length of the objective amounts to between 2.28 and 2.79, the quotient of the focal length of the middle group and the total focal length of the objective amounts to between 3.02 and 3.69, and the quotient of the focal length of the rear group and the total focal length of the objective amounts to between 3.50 and 4.29.

Abstract: Systems and methods for long working distance optical coherence tomography (OCT). According to an aspect, an OCT system includes a reference arm. Further, the OCT system includes a sample arm operably connected to the reference arm. The sample arm includes a scanner configured to scan an optical beam. The sample arm also includes an objective positioned a predetermined distance from the scanner, configured to receive the optical beam, and to direct the optical beam to an object positioned at about the predetermined distance from the scanner for imaging of the object.

Abstract: An optical imaging lens includes a plurality of lens elements arranged in the given order from an object side to an imaging side. Each of the lens elements has a refracting power, an object-side surface facing toward the object side and an image-side surface facing toward the image side. The lens elements include a first lens element closest to the object side, a second lens element second closest to the object-side, a third lens element having a positive refracting power, and a fourth lens element having its object-side and image-side surfaces being aspheric. The object-side surface of the first lens element has a concave portion in the vicinity of the optical axis. The third lens element has at least one of the object-side and image-side surfaces being aspheric.

Abstract: Projection lens having improved properties such as a high throughput are described. In one embodiment, a projection lens is described comprising in sequential order from a screen side a first lens group, a second lens group of positive refractive power, and a third lens group of positive refractive power. At least one lens group has an aspheric surface. The ratio of the focal length of the projection lens (F) to the focal length of each of the lens groups (F1, F2, and F3) is such that |F1/F|>5, 0.5<|F2/F|<0.9, and 1<F3/F<8. In another embodiment, a projection lens is described comprising in sequential order from a screen side a first lens group, a second lens group of positive refractive power, and a third lens group of positive refractive power. At least one lens group has an aspheric surface. The ratio of the focal length of the projection lens (F) to the focal length of each of the lens groups (F1, F2, and F3) is such that |F1/F|>5, 0.5<|F2/F|<2.0, and 1.4<F3/F<8.

Abstract: An imaging lens includes a first lens having positive refractive power; a second lens having positive refractive power; and a third lens having positive refractive power, arranged in the order from an object side to an image plane side. The first lens and the third lens have object-side surfaces and image plane-side surfaces, curvature radii of which are both positive. When the first lens has refractive power P1, the second lens has refractive power P2, the third lens has refractive power P3, the first lens has a focal length f1, and the third lens has a focal length f3, the imaging lens satisfies the following conditional expressions: 5.0<(P1+P3)/P2<8.

Abstract: An imaging lens includes a first lens; a second lens; and a third lens arranged from an object side to an image plane side. The first lens has an object-side surface with a positive curvature radius. The second lens has an object-side surface and an image plane-side surface with negative curvature radii. The third lens has an object-side surface and an image plane-side surface with positive curvature radii. The object-side surface and the image plane-side surface of the third lens are respectively formed as an aspheric shape having an inflexion point. When the whole lens system has a focal length f, the first lens has a focal length f1, the second lens has a focal length f2, and the third lens has a focal length f3, the imaging lens satisfies the following conditional expressions: f1<f2 1.0<f1/f<1.5 0.7<f2/f3<1.2.

Abstract: An imaging lens includes a first lens; a second lens; and a third lens arranged from an object side to an image plane side. The first lens has an object-side surface having a positive curvature radius R1f and an image plane-side surface having a negative curvature radius R1r. The second lens has an object-side surface and an image plane-side surface with negative curvature radii. The third lens has an object-side surface and an image plane-side surface with positive curvature radii and formed as aspheric surfaces having inflexion points. When the whole lens system has a focal length f, the first lens has a focal length f1, the second lens has a focal length f2, and the third lens has a focal length f3, the imaging lens satisfies the following conditional expressions: f1<f2<f3 1.0<f1/f<1.5 ?0.

Abstract: An image capturing optical system includes, in order from an object side to an image side: the first lens element with positive refractive power having a convex object-side surface, the second lens element with positive refractive power having a concave object-side surface and a convex image-side surface, the third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, wherein the object-side surface and the image-side surface of the third lens element are aspheric. By such arrangement, the total track length and the photosensitivity of the image capturing optical system can be effectively reduced while retaining high image quality. The image capturing optical system can also be applied to an infrared optical system.

Abstract: A projecting lens for projecting a light of an image generating device onto a screen is provided. The image generating device has a light valve. The projecting lens includes a first lens group and a second lens group. The first lens group has an imaging optical axis and a first effective refractive power. The second lens group has a second effective refractive power, and is disposed between the first lens group and the light valve. The light projected from the light valve to the second lens group generates an intermediate image, which is focused on the screen via the first lens group to form an image. A center of the image and a center of the light valve are located on the same side of the optical axis, and a center of the intermediate image is located on the other side of the optical axis.

Abstract: A lens system includes a first, a second and a third lenses, and an image plane. The lens system satisfies the formulae: FB/TTL>0.30; G1R2/F1>19.54; and D1/D2<1.62. FB denotes a distance between a nearest point of an image-side surface of the third lens relative to the image plane and the image plane, TTL denotes the total track length of the lens system, G1R2 denotes the curvature radius of the vertex of an image-side surface of the first lens, F1 denotes the focal length of the first lens. D1 denotes an orthogonal distance between a farthest point of an image-side surface of the second lens relative to an optical axis of the lens system and a central point of the image-side surface of the second lens, along a direction substantially perpendicular to the optical axis. D2 denotes an orthogonal distance between the farthest point and the central point along the optical axis.

Abstract: An infrared lens 1a includes first to third lenses L1 to L3 which are made of zinc sulfide and arranged in this order from an object side. Each of the first to third lenses L1 to L3 is configured as a positive meniscus lens of which convex surface is opposed to the object. The lenses L1 to L3 are formed by heat-press molding raw powder of zinc sulfide using a lens-shaped mold. In addition, a concave surface (the surface opposed to the image side) of the first lens L1 is formed as a diffractive surface.

Abstract: A lens module has a magnified side and a reduced side having an imaging surface. The lens module includes a first, a second, and a third lens groups having positive refractive powers respectively. The first lens group includes a first and a second lenses. A value calculated by dividing a distance between a center of a surface of the first lens facing the magnified side and the imaging surface by the effective focal length of the lens module is greater than or equal to 1 and smaller than or equal to 3. The second lens group located between the first lens group and the reduced side includes a third and a fourth lenses. The third lens group located between the second lens group and the reduced side includes a fifth lens. Refractive powers of the first to the fifth lenses are negative, positive, positive, negative and positive, respectively.

Abstract: A fixed-focus lens including a first lens group, a second lens group, and a third lens group arranged in sequence from a magnified side towards a reduced side is provided. The first lens group has a positive refractive power, and includes a first lens and a second lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the first lens and the second lens are respectively negative and positive. The second lens group has a positive refractive power, and includes a third lens, a fourth lens, and a fifth lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the third lens, the fourth lens, and the fifth lens are respectively positive, negative, and positive. The third lens group has a positive refractive power, and includes a sixth lens. A refractive power of the sixth lens is positive.

Abstract: Providing an optical system having excellent optical performance over entire focusing range from infinity to a close distance, a method for focusing the optical system, and an imaging apparatus equipped therewith. The optical system includes, in order from an object, a first lens group G1 having positive refractive power, and a second lens group G2 having positive refractive power. The second lens group G2 is movable along an optical axis for varying focusing. The first lens group G1 satisfies a given conditional expression.

Abstract: An infrared lens 1a includes first to third lenses L1 to L3 which are made of zinc sulfide and arranged in this order from an object side. Each of the first to third lenses L1 to L3 is configured as a positive meniscus lens of which convex surface is opposed to the object. The lenses L1 to L3 are formed by heat-press molding raw powder of zinc sulfide using a lens-shaped mold. In addition, a concave surface (the surface opposed to the image side) of the first lens L1 is formed as a diffractive surface.

Abstract: This invention provides a photographing optical lens system in order from an object side to an image side including: a first lens element with positive refractive power having a convex object-side surface, a second lens element with positive refractive power having a convex image-side surface, a third lens element with positive refractive power having a convex object-side surface and a concave image-side surface, both the two surfaces being aspheric and at least one of them having at least one inflection point formed thereon; wherein the photographing optical lens system further comprises an aperture stop configured between an imaged-object and the second lens element, and there are three lens elements with refractive power.

Abstract: A fixed-focus lens includes a first, a second, and a third lens groups arranged in sequence from the enlarged side to the reduced side and having positive refractive powers. The first lens group includes a first, a second, and a third lenses from the enlarged side to the reduced side. The second lens group includes a fourth, a fifth, and a sixth lenses from the enlarged side to the reduced side. The third lens group includes a seventh lens. The lens of the first lens group closest to the enlarged side in the fixed-focus lens has a concave surface. The distance between the lens surface of the second lens group closest to the reduced side and the lens surface of the third lens group closest to the enlarged side is L1. The overall length of the fixed-focus lens is L. The fixed-focus lens satisfies 0.1<L1/L<0.5.

Abstract: A fixed-focus lens includes a first, a second, and a third lens groups arranged in sequence from the enlarged side to the reduced side and having positive refractive powers. The first lens group includes a first, a second, and a third lenses from the enlarged side to the reduced side. The second lens group includes a fourth, a fifth, and a sixth lenses from the enlarged side to the reduced side. The third lens group includes a seventh lens. The lens of the first lens group closest to the enlarged side in the fixed-focus lens has a concave surface. The distance between the lens surface of the second lens group closest to the reduced side and the lens surface of the third lens group closest to the enlarged side is L1. The overall length of the fixed-focus lens is L. The fixed-focus lens satisfies 0.1<L1/L<0.5.

Abstract: A lens system including: 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 positive or negative refractive power, wherein the first lens group comprises four or less lenses, and the first through third lens groups are movable, independently, during focusing and have magnifications in a range from ?1 to 0.

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

Abstract: Providing an optical system having excellent optical performance over entire focusing range from infinity to a close distance, a method for focusing the optical system, and an imaging apparatus equipped therewith. The optical system includes, in order from an object, a first lens group G1 having positive refractive power, and a second lens group G2 having positive refractive power. The second lens group G2 is movable along an optical axis for varying focusing. The first lens group G1 satisfies a given conditional expression.

Abstract: An optical lens system for taking image consisting of: an aperture stop; a first lens element with positive refractive power having a convex object-side surface; a plastic second lens element with positive refractive power having a concave object-side surface and a convex image-side surface, at least one of the object-side and the image-side surfaces of the second lens element being aspheric; and a plastic third lens element with positive refractive power having a convex object-side surface, at least one of the object-side and the image-side surfaces of the third lens element being aspheric. A focal length of the optical lens system for taking image is f, a focal length of the second lens element is f2, a focal length of the third lens element is f3, and at least one of the relations of f/f2 and f/f3 is larger than 0.1.

Abstract: A lens with a very high degree of barrel distortion at the image plane (or pincushion distortion in object space).

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

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

Abstract: A zoom optical system, in order from a reduction side to a magnification side, includes a first lens unit having positive optical power, a second lens unit having the positive optical power, a third lens unit having negative optical power, and a fourth lens unit having the positive optical power, wherein respective intervals between the first, second, third and fourth lens units change during zooming, a conjugate position on the magnification side with respect to a conjugate position on the reduction side, and a position of a pupil of the zoom optical system with respect to the conjugate position on the reduction side, are substantially fixed over an entire zooming range, and during zooming from a wide angle end to a telephoto end, the fourth lens unit moves toward the magnification side, and an interval between the first lens unit and the fourth lens unit increases.

Abstract: An image lens array, from object side, comprises a first lens, an aperture, a second lens and a third lens. The first lens is a positive meniscus lens with a convex surface facing the object side; the second lens is positive meniscus lens with a convex surface facing the image side; the third lens is a positive meniscus lens with a convex surface facing the object side; and the first lens, the second lens and the third lens are made of the same plastic material, a focal length of the image lens array is f, a combined focal length of the first and second lenses is f12, a relation between the f and f12 can satisfy the equation: 1.0<f12/f<1.3.

Abstract: The photographing lens of the present invention includes, starting from the object side: an aperture stop having a predetermined aperture; a first lens group having a positive overall refractive power; a second lens group having a positive overall refractive power; and a third lens group having a positive overall refractive power. The first lens group is a cemented lens with, from the object side, a first lens with a positive refractive power and a second lens with a negative refractive power. The second lens group includes a third lens with a positive refractive power and at least one aspherical surface. The third lens group includes a fourth lens with a positive refractive power and at least one aspherical surface. The present invention provides a thin photographing lens for mobile devices with cameras, which has a short total length and an exit angle up to around 20° and corrects various aberrations.

Abstract: A single focus lens includes, in order from the object side: a first lens component of positive refractive power with a convex surface on the object side; a diaphragm stop; a second lens component that is made of plastic, has at least one aspheric surface and a meniscus shape, and has a concave surface on the object side near the optical axis; and, a third lens component of positive refractive power with two aspheric surfaces, one of which is convex on the object side near the optical axis. Each lens component that forms the single focus lens may consist of a lens element. Specified conditions are satisfied in order to reduce aberrations, to insure that the light rays at the image plane are substantially orthogonal to the image plane, and to insure that a sufficient back focus is provided to allow for insertion of other optical elements.

Abstract: A projection objective having a variable focal length, preferably serving to image tilting mirror matrices or reflecting and/or transmitting LCDs, said projection objective comprising three groups of lenses (G1, G1, G3) arranged on a common optical axis, wherein, starting from the side facing the projection screen, the first lens group (G1), serving the purpose of focussing, and the second lens group (G2), serving the purpose of varying the focal length, are arranged on the optical axis in a variably positioned manner, and the third lens group (G3) is stationary. According to the invention, the following condition is met: 1.0 h max<dG2-G3<1.5 h max and s?10 mm, wherein h max is the maximum object height, dG2-G3 is the distance between the lens group G2 and the lens group G3 in a first position, and s is the object-side intercept distance or distance from the vertex to the object.

Abstract: A single focus lens is disclosed that is formed of only three lens components. In order from the object side, these are: a first lens component that has positive refractive power and includes a first lens element; an aperture diaphragm; a second lens component that has positive refractive power, at least one aspheric lens surface, and includes a second lens element made of plastic; and a third lens component that has positive refractive power, at least one aspheric lens surface, and includes a third lens element made of plastic. The following condition is satisfied: 1.0<f1/f<5.0 where f1 is the focal length of the first lens component, and f is the focal length of the single focus lens.

Abstract: The photographing lens of the present invention includes, starting from the object side: an aperture stop having a predetermined aperture; a first lens group having a positive overall refractive power; a second lens group having a positive overall refractive power; and a third lens group having a positive overall refractive power. The first lens group is a cemented lens with, from the object side, a first lens with a positive refractive power and a second lens with a negative refractive power. The second lens group includes a third lens with a positive refractive power and at least one aspherical surface. The third lens group includes a fourth lens with a positive refractive power and at least one aspherical surface. The present invention provides a thin photographing lens for mobile devices with cameras, which has a short total length and an exit angle up to around 20° and corrects various aberrations.

Abstract: A single focus lens is disclosed that is formed of only four lens components, which are arranged in positive, negative, positive and relatively weak positive or negative refractive power order from the object side, with a stop arranged between the first and second lens components. The third lens component has a convex surface on its image side, and the fourth lens component has a meniscus shape, is made of plastic, includes at least one aspheric surface, and is concave on its image side. The second lens component is formed of a single lens element, and various conditions are preferably satisfied so as to provide a compact lens having a short overall length while favorably correcting various aberrations.

Abstract: A single focus lens is disclosed that is formed of only three lens components. In order from the object side, these are: a first lens component that has positive refractive power and includes a first lens element; an aperture diaphragm; a second lens component that has positive refractive power, at least one aspheric lens surface, and includes a second lens element made of plastic; and a third lens component that has positive refractive power, at least one aspheric lens surface, and includes a third lens element made of plastic. The following condition is satisfied: 1.0<f1/f<5.0 where f1 is the focal length of the first lens component, and f is the focal length of the single focus lens.

Abstract: A real image finder optical system, having a relay lens system, comprises a positive first lens group, a positive second lens group, and a positive third lens group, in this order from the object. The finder optical system is arranged to form an inverted primary image of an object by the positive first lens group, and to form an erected secondary image by the positive second lens group functioning as the relay lens system so that the erected secondary image can be viewed through the third lens group. Furthermore, the second lens group comprises a diffractive optical element having at least one diffractive surface having positive diffractive power.

Abstract: In a non-flexible endoscope consisting of an insertion section and an eyepiece section which are separable from each other, an optical system configured so as to correct chromatic aberration produced by an observation optical system disposed in the insertion section with an eyepiece optical system disposed in the eyepiece section. The optical system according to the present invention selects a simple composition for the observation optical system so that it is manufacturable at a low cost and disposable, and is configured so as to have favorable optical performance as a whole by correcting chromatic aberration produced by the observation optical system with the eyepiece optical system.

Abstract: A plan apochromatic microscope objective lens is disclosed having few constituent lens elements, a large numerical aperture, excellent flatness across the entire field of view of the objective lens, and a relatively long working distance. The objective lens comprises, in order from the object side, first, second, and third lens groups. The first lens group comprises a meniscus lens having a concave surface oriented toward the object side, and a positive meniscus lens having a concave surface oriented toward the object side. The second lens group comprises a simple lens, a cemented lens including a negative lens and a positive lens, and a cemented lens including a positive lens and two negative lenses. The third lens group comprises a cemented lens with overall weak refractive power and including a positive lens and a negative lens. The objective lens satisfies a number of conditional expressions.

Abstract: An eyepiece lens comprising, from front to rear, a first lens unit of positive refractive power having a negative lens and a positive lens, a second lens unit of positive refractive power and a third lens unit of positive refractive power, wherein at least one of the lens surfaces in the first lens unit to the third lens unit is made aspherical, and wherein the apparent field of view covers an angle of about 50 degrees, the eye relief is elongated, and the field curvature is corrected well.

Abstract: The lens system includes, in order from an object side, a 1-st lens unit having a positive refractive power which has at least two positive lens elements and a negative lens element positioned on an image side of said positive lens elements, a 2-nd lens unit having a positive refractive power and a 3-rd lens unit having a positive refractive power. During focusing, both 1-st and 3-rd lens units are fixed, whereas the 2-nd lens unit is movable along an optical axis. The lens system satisfies at least one of the conditions 1.8<F1/f<2.4 and 0.8<F2/f<0.96.

Abstract: Optical systems for endoscopes, borescopes, dental scopes, and the like which are characterized by having three groups of lenses of positive optical power and an external entrance pupil. Typically, all three groups of lenses are displaced from the pupil and focal planes. As a consequence, the displaced groups take part in the image transfer as well as in the pupil transfer. The optical power requirements can thus be shifted from one group to another, distributing as well as reducing the overall power requirement. Moreover, the aberration correction can also be shared between these groups. The first group, which conventionally has the highest optical power, and consequently a large amount of aberrations to be corrected, can in this way transfer some of the optical aberration correction to the other groups. The sharing of the optical functions and aberration correction results in a fully integrated optical system.

Abstract: An eyepiece having an apparent visual angle of 40.degree. or greater is provided, in succession from the eyepoint side, with a first lens unit G1 having positive refractive power, a second lens unit G2 having positive refractive power, and a third lens unit G3 having positive refractive power. The first lens unit G1 has a positive lens component, the second lens unit G2 has a positive lens component, and the third lens unit G3 has a cemented lens consisting of a positive lens component and a negative lens component. At least one of the lens surfaces of the first to third lens units G1 to G3 is formed into an aspherical shape.

Abstract: The present invention provides a photographic lens system capable of close-up photography in which various aberrations such as spherical aberration and coma, and curvature of field are concurrently corrected in a well-balanced state and which is relatively bright as expressed by an F-number of about 2.8, and is characterized by comprising a first lens group G.sub.1 which includes a front sub-group G.sub.1F having positive refracting power and a rear sub-group G.sub.1R having negative refracting power and has positive refracting power in its entirety, a second lens group G.sub.2 having positive refracting power in its entirety, and a third lens group G.sub.3 having positive refracting power in its entirety, the lens of the front sub-group G.sub.1F nearest to the image side being concave on the image side and the lens of the rear sub-group G.sub.

Abstract: A high resolution with at the same time high testing speed is required of scanning objectives for the linewise or pointwise three-dimensional scanning of object surfaces. In order to be able to image as many image points as possible with high resolution, the scanning objective must exhibit a correspondingly large numerical aperture with, at the same time, a large image field. For this purpose, it is constructed of three lens groups (1; 2; 3). The first and second lens groups (1; 2) effect both a scan angle reduction and a pupil enlargement. The entrance pupil (61) is imaged into the entrance pupil (63) of the third lens group (3). The third lens group (3) has a large numerical aperture of, for example, 0.6. Furthermore, the real intermediate image (5) is imaged by the second lens group (2) with positive refractive power and greater focal length (f) than the first lens group (1), at infinity. With a beam diameter (D) at the entrance of the scanning objective of 7.5 mm, a scan angle (.theta.) of +/-16.degree.

Abstract: Binoculars designed to provide a large aided static field of view are provided. The binoculars are characterized by S/D ratios of above 2.8, where S is the binocular' aided static field of view calculated by multiplying the binoculars' magnifying power by the binoculars' semi field of view in object space and D is given by tan.sup.-1 [(R.sub.ex +1.5)/13], where R.sub.ex is the radius of the binoculars exit pupil and where R.sub.ex and the constants 1.5 and 13 are measured in millimeters. As a result of the increased S/D ratio, the binoculars' of the invention minimize the sensation of tunnel vision which normally occurs when binoculars are used and reduce the user's apprehension of missing activities in his or her peripheral vision. In certain embodiments, a movable field lens unit is employed to provide variable power and a negative corrector lens unit is employed for aberration correction and to minimize the size of the binoculars. The binoculars are suitable for mass production and general consumer use.

Abstract: A collimating lens (10) is constructed of a lens assembly having a first lens set (12, 14) at a first end of the assembly and a second lens set (20) at a second end of the assembly with a doublet (16, 18) disposed between the first lens set and the second lens set. The first lens set includes a plurality of lens elements (12, 14) each of which has positive optical power. The second lens set has a single lens element (26) of positive optical power and a concave surface (40) facing subject matter to be viewed by the collimating lens. The doublet lens element includes a lens element (16) constructed of flint glass and having a negative optical power plus a lens element (18) constructed of crown glass and having a positive optical power. In the doublet lens element, the negative power lens element has two concave surfaces, the positive-power lens element has two convex surfaces, and the two lens elements are cemented together to provide for a broad-band chromatic correction.

Abstract: A macro lens comprises first to third lens groups having positive powers and an aperture stop disposed the first and second lens groups. The first lens group, aperture stop and second lens group remain fixed with respect to one another and movable as one unit relative to the third lens group for focusing. The third lens group is stationary with respect to an image plane of the macro lens.

Abstract: A finder optical system including an objective having a positive refractive power, an image erecting optical member for erecting an image formed by the objective, and an eyepiece for allowing observation of the image formed by the objective and erected by the image erecting optical member. The objective consists of a first positive lens component and a second negative lens component, or a single lens having a convex surface on the object side. This finder optical system has a simple composition, a compact external design and a relatively wide field angle.