Abstract: An image pickup optical system of the present invention comprises, in order from an object side, a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a positive refractive power, a fifth lens having a negative refractive power, which is formed into a meniscus shape facing its concave surface toward the object side, and an aperture located on the most object side. Thus, there can be provided an image pickup optical system and an image pickup apparatus having the same, in which the maximum effective lens aperture is small and various aberrations are corrected properly.

Abstract: An imaging lens includes plastic-made first, second, third, fourth, and fifth lens elements arranged in the given order from an object side to an imaging side, each having object-side and imaging-side surfaces facing toward the object and imaging sides, respectively. The first lens element has a positive focusing power, and the object-side surface thereof is a convex surface. The second lens element has a negative focusing power, and the imaging-side surface thereof is a concave surface. The third lens element has a positive focusing power, and each of the imaging-side and object-side surfaces thereof is a convex surface. The fourth lens element is a meniscus lens, and the imaging-side surface thereof is a convex surface. The imaging-side surface of the fifth lens element has a concave area in a vicinity of an optical axis of the fifth lens element.

Abstract: Disclosed herein is a zoom lens including a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group. The zoom lens satisfies following conditional expressions (1) and (2), 0.03<H1?/f1<0.3??(1) 0.3<|f2|/?(fw·ft)<0.65??(2) where H1? is an interval from a vertex of a surface nearest to the image side in the first lens group to a principal point on the image side of the first lens group (? denotes the object side, and + denotes the image side), f1 is focal length of the first lens group, f2 is focal length of the second lens group, fw is focal length of an entire lens system at a wide-angle end, and ft is the focal length of the entire lens system at a telephoto end.

Abstract: An imaging lens includes, in this order from an object side, an aperture stop ST, a positive first lens L1, a negative second lens L2 having a meniscus shape that directs a convex surface on the object side near an optical axis, a positive third lens L3, a positive fourth lens L4 having a meniscus shape that directs a concave surface on the object side near an optical axis, and a negative fifth lens L5 having a meniscus shape that directs a convex surface on the object side near an optical axis.

Abstract: This invention provides an imaging lens assembly including five lens elements with refractive power, in order from an object side toward an image side: a first lens with positive refractive power having a convex object-side surface, a second lens with negative refractive power, a third lens having a concave object-side surface, a fourth lens with positive refractive power having an object-side surface and a convex image-side surface, and at least one of both surfaces thereof being aspheric, a fifth lens with negative refractive power having a concave image-side surface with at least one inflection point formed thereon. An aperture stop is positioned between an imaged object and the second lens. The imaging lens assembly further comprises an electronic sensor on which an object is imaged. With such arrangement, the size and the optical sensitivity of the lens assembly can be reduced. A high image resolution is also obtained.

Abstract: An imaging lens includes an aperture stop, a positive first lens with a biconvex shape, a negative second lens; a negative third lens, a positive fourth lens, and a negative fifth lens arranged in this order from an object side. When the whole lens system has a focal length f, focal lengths and Abbe's numbers of the first and the second lenses are f1, ?d1, f2, and ?d2, focal lengths of the fourth and fifth lenses are f4 and f5, a composite focal length of the first lens L1 and the second lens L2 is f12, and a distance from a surface of the first lens L1 on the object side to a surface of the fifth lens L5 on the image side is ?d, the imaging lens satisfies the following conditional expressions: 0.7<f12/f<1.4 0.2<|f1/f2|<0.6 15<?d1??d2 0.4<f4/f<1.0 ?d/f<1.2 |f5/f|<1.

Abstract: This invention provides an imaging optical lens assembly including: in order from an object side toward an image side: a first lens with positive refractive power and having a convex object-side surface, a second lens with negative refractive power and having a convex object-side surface and a concave image-side surface, a third lens with positive refractive power and having a concave object-side surface and a convex image-side surface, a fourth lens with negative refractive power and having a concave image-side surface, the object-side and image-side surfaces being aspheric, and a fifth lens having a concave image-side surface, the object-side and image-side surfaces being aspheric. The imaging optical lens assembly further comprises an aperture stop, disposed between an imaged object and the second lens, and an electronic sensor, disposed at the image plane for image formation.

Abstract: Provided is an imaging lens, including a first lens having positive (+) refractive power; a second lens having negative (?) refractive power; a third lens having negative (?) refractive power; a fourth lens having negative (?) refractive power; and a fifth lens having positive (+) refractive power in order from an object side, where the third lens is formed concavely at an object side.

Abstract: Provided is a small-sized five-element image pickup lens which ensures a sufficient lens speed of about F2 and exhibits various aberrations being excellently corrected. The image pickup lens is composed of, in order from the object side, a first lens with a positive refractive power, including a convex surface facing the object side; a second lens with a negative refractive power, including a concave surface facing the image side; a third lens with a positive or negative refractive power; a fourth lens with a positive refractive power, including a convex surface facing the image side; and a fifth lens with a negative refractive power, including a concave surface facing the image side. The image-side surface of the fifth lens has an aspheric shape, and includes an inflection point at a position excluding an intersection point with the optical axis.

Abstract: Providing for a fixed focus optical system exhibiting extended depth of field is provided herein. By way of example, a compact and fast optical system that yields an asymmetric modulation transfer function (MTF) is disclosed. In some aspects, the asymmetric MTF results in extended depth of field for near field objects. Such a response can be particularly beneficial for small handheld cameras or camera modules having high resolution. According to some disclosed aspects, the resolution can be about 8 mega pixels. Additionally, the optical system can comprise four lenses in one aspect and five lenses in another, while remaining below about 5.3 mm total track length (TTL) for the respective systems. In at least one application, the disclosed optical systems can be employed for a high resolution compact camera, for instance in conjunction with an electronic computing device, communication device, display device, surveillance equipment, or the like.

Abstract: This invention provides a photographing optical lens assembly including, in order from an object side toward an image side: a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power having a concave object-side surface and a concave image-side surface, a third lens element with positive refractive power, a fourth lens element with negative refractive power having a convex object-side surface and a concave image-side surface, and at least one of surfaces thereof being aspheric, a plastic fifth lens element having a convex object-side surface and a concave image-side surface with at least one inflection point. An aperture stop is positioned between an imaged object and the third lens element. The photographing optical lens assembly further comprises an electronic sensor on which the object is imaged.

Abstract: Disclosed herein is an imaging lens suitable for a camera module using a high resolution imaging sensor, decreasing a flare phenomenon and reducing the sensitivity. The imaging lens comprises, in order from the object side, a first lens having positive (+) refractive force; a second lens having negative (?) refractive force; a third lens having positive (+) refractive force; a fourth lens having positive (+) refractive force; and a fifth lens having negative (?) refractive force, wherein an object side plane of the third lens is convexly formed.

Abstract: The present invention provides an imaging lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power, at least one of the object-side and image-side surfaces thereof being aspheric; a fourth lens element, the image-side surface thereof being aspheric and provided with at least one inflection point; a fifth lens element having a concave object-side surface, at least one of the object-side and image-side surfaces thereof being aspheric; and an aperture stop disposed between an imaged object and the second lens element. Such an arrangement of optical elements can effectively reduce the total track length and sensitivity of the optical system, and image quality can also be improved.

Abstract: Provided is a fast image reading lens system capable of achieving compactness and satisfactorily correcting various aberrations. The image reading lens system includes, in order from an object side: a positive first lens of which a convex surface faces toward the object side; a second lens formed as a biconcave lens; a third lens formed as a biconvex lens; a positive fourth lens of which a convex surface faces toward an image side; and a negative fifth lens of which a convex surface faces toward the image side. Assuming that a focal length of the whole lens system is f, a focal length of the fourth lens is f4, and a space between an image side surface of the fourth lens and an object side surface of the fifth lens on an optical axis is D8, the lens system satisfies the following conditional expressions: 0.06<D8/f<0.16, and 0.77<f4/f<1.81.

Abstract: A zoom lens having an optical element for deflecting an optical path includes, in order from an object: a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; and a fifth lens group having negative refractive power. The third lens group has a plurality of lenses, and the following conditional expressions 1.00<PL/fW<1.75 and 0.30<PL/fT<0.45 are satisfied, where PL denotes an optical path length of the optical element for deflecting the optical path, fW denotes a focal length of the zoom lens in a wide angle end state, and fT denotes a focal length of the zoom lens in a telephoto end state.

Abstract: An optical lens system for taking image comprises, in order from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a fourth lens element with positive refractive power; a fifth lens element with refractive power; and an aperture stop located between an object to be photographed and the second lens element. In the optical lens system for taking image, the number of the lens elements with refractive power being limited to five. Such lens arrangements can effectively reduce the volume of the optical lens system, reduce the sensitivity of the optical lens system and obtain higher resolution.

Abstract: An imaging lens is provided and includes: in order from the object side, a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a convex surface on the image side near the optical axis and having a positive refractive power; a fourth lens having a positive refractive power near the optical axis; and a fifth lens having a negative refractive power near the optical axis.

Abstract: An imaging lens is provided and includes: in order from the object side, a first lens having a positive refractive power; a second lens having a negative refractive power; a third lens having a concave surface on the image side near the optical axis and having a positive refractive power; a fourth lens having a positive refractive power near the optical axis; and a fifth lens having a negative refractive power near the optical axis. An image side surface of the fifth lens is concave near the optical axis and has a region where a negative power of the region decreases toward a periphery of the fifth lens as compared with a negative power near the optical axis.

Abstract: An image pickup lens includes: a first lens with a positive power, including a convex surface facing the object side; an aperture stop; a second lens with a negative power, including a concave surface facing the image side; a third lens with a positive or negative power; a fourth lens with a positive power, including a convex surface facing the image side; and a fifth lens with a negative power, including a concave surface facing the image side. The surface of the fifth lens facing the image side is an aspheric surface and includes an inflection point. The image pickup lens satisfies the predetermined condition relating to a focal length of the first lens.

Abstract: An image pickup optical system made of five lenses, includes in order from an object side, an aperture stop, a first lens L1 having a positive refracting power, a second lens L2 having a negative refracting power, a third lens L3 having a positive refracting power, a fourth lens L4 having a positive refracting power, and a fifth lens L5 having a negative refracting power. Moreover, an image pickup apparatus includes this image pickup optical system.

Abstract: A zoom lens includes first to fifth lens groups respectively having positive, negative, positive, positive, and negative refractive powers in that order from the object side. Zooming is performed by moving the second lens group and the fourth lens group in an optical-axis direction. The first lens group includes a front lens group having a negative refractive power, an optical member for bending an optical path, and a rear lens group having a positive refractive power in that order from the object side. The front lens group is a cemented lens in which a first lens having a negative refractive power is bonded to a second lens having a positive refractive power in that order from the object side to the image side.

Abstract: An imaging lens includes first to fourth lens units in order from the object side to the image side. The first, third, and fourth lens units have a positive refractive power. The second and fifth lens units have a negative refractive power. During focusing from an object at infinity to a close object, the first, third, and fifth lens units do not move, and the second and fourth lens units respectively move toward the image side and the object side. The fifth lens unit includes a fifth-a lens unit having a negative refractive power which moves in a direction having a component perpendicular to an optical axis to shift a image position, and a fifth-b lens unit having a positive refractive power. Focal lengths of the third lens unit, the entire system of the imaging lens, the fifth-a lens unit, and the fifth-b lens unit are adequately set.

Abstract: An optical lens system for taking image comprises, in order from the object side to the image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface; a fourth lens element with positive refractive power; a fifth lens element with refractive power; and an aperture stop located between an object to be photographed and the second lens element. In the optical lens system for taking image, the number of the lens elements with refractive power being limited to five. Such lens arrangements can effectively reduce the volume of the optical lens system, reduce the sensitivity of the optical lens system and obtain higher resolution.

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

Abstract: A zoom lens configured by arranging a first lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group in order from the object side to the image side, and further having an aperture diaphragm on the object side of the third lens group. In the first lens group, a first lens, a second lens, and a third lens are located in order from the object side to the image side. In the second lens group, a fourth lens, a fifth lens, and a sixth lens are located in order from the object side to the image side. The third lens group is made up of a seventh lens which is a convex lens, the fourth lens group is made up of at least two or more cemented lenses, the third lens group and the fourth lens group include at least one surface formed into an aspherical surface.

Abstract: An imaging lens is provided and includes: in order from an object side of the imaging lens, an aperture diaphragm; a first lens having a positive refractive power and having a convex surface on the object side; a second lens having a negative refractive power and having a concave surface on the object side; and a third lens having a meniscus shape having a convex surface on the object side in the vicinity of an optical axis thereof, each of the first lens, the second lens and the third lens having at least one aspherical surface, and the imaging lens satisfying the following conditional expressions. 0.9<|f2/f|<11??(1) 1.2<|f3/f|<100??(2) f represents a focal length of the imaging lens; f2 represents a focal length of the second lens; and f3 represents a focal length of the third lens.

Abstract: An image pickup optical system for forming a light flux from an object into an optical image on an image pickup element, is provided with, in order from an object side thereof: a first lens with a negative power in a meniscus shape including a convex surface facing the object side; a second lens in a bioconcave shape; a third lens with a positive power including a convex surface facing an image surface side; and a fourth lens with a positive power including a convex surface facing the image surface side. The first lens and the third lens are glass lenses and the second lens and the fourth lens are plastic lenses.

Abstract: An optical system comprising two lens cells, each lens cell comprising multiple lens elements, to provide imaging over a very wide image distance and within a wide range of magnification by changing the distance between the two lens cells. An embodiment also provides scannable laser spectroscopic measurements within the field-of-view of the instrument.

Abstract: There is provided a high-definition imaging optical system including: an aperture stop; a first lens disposed at an image side of the aperture stop, the first lens having a positive refractive power and having a convex object-side surface; a second lens disposed at an image side surface of the first lens; a third lens disposed at an image side surface of the second lens; a fourth lens having a convex image-side surface and having a positive refractive power; and a fifth lens having a concave image-side surface and having a negative refractive power, wherein a combined refractive power of the second and third lenses is negative. The optical system is high-performing and compact and can be further improved in resolution. Also, the optical system can correct chromatic aberration and improve color fringing in the case of indoor or outdoor photographing.

Abstract: There is provided a subminiature optical system mounted in a mobile communication terminal and a personal digital assistant (PDA) or used for a monitoring camera and a digital camera.

Abstract: A zoom lens comprises the following lens groups in the order from an object side a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a positive refracting power; and a fifth lens group having a positive refracting power; wherein, upon zooming from a wide-angle end state to a telephoto end state, at least the first lens group and the fourth lens group move to the object side to vary a space between the first lens group and the second lens group, vary a space between the second lens group and the third lens group, vary a space between the third lens group and the fourth lens group, and vary a space between the fourth lens group and the fifth lens group; and wherein the fifth lens group comprises a front lens group, and a rear lens group arranged with an air space on an image side of the front lens group, and the fifth lens group is configured to move the front lens group i

Abstract: An imaging lens is provided and includes: a positive first lens with a convex surface directed to the object side; a second lens having a negative meniscus shape with a concave surface directed to the image side; a third lens having a positive meniscus shape with a convex surface directed to the image side; a negative fourth lens with both surfaces being an aspheric surface and the image-side surface being concave in the proximity of the optical axis; and a positive or negative fifth lens with both surfaces being an aspheric surface, in order from the object side. The following conditional expressions are satisfied as for Abbe numbers vd1 and vd2of the first lens and the second lens and Abbe number vd4 of the fourth lens.

Abstract: An exemplary projection lens includes, in this order from the magnification side to the minification side thereof, a negative lens group of negative fraction power, and a positive lens group of positive fraction power. The projection lens satisfies the formulas of: ?2.5<F1/F<?1.5; and 1.3<F2/F<1.5, where F1, F2, and F respectively represent the effective focal lengths of the negative lens group, the positive lens group, and the projection lens.

Abstract: A zoom lens having five lens groups arranged in succession. The zoom lens is configured such that when zooming from a short focal length end toward a long focal length end, the second lens group lens moves toward the third lens group and the fourth lens group moves toward a side of the third lens group, and the fifth lens group corrects the zooming and a shift in a position of an imaging plane of the zoom lens caused by movement of the third lens group and the fourth lens group.

Abstract: An object is to provide: a zoom lens system that has a reduced overall length, a high resolution, and a variable magnification ratio as high as 9 or greater and that is satisfactorily adaptable for wide-angle image taking where the view angle at a wide-angle limit is 70° or greater; an imaging device employing this zoom lens system; and a thin and compact camera. The zoom lens system has a plurality of lens units each composed of at least one lens element, and, in order from the object side to the image side, comprises a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, a fourth lens unit and a fifth lens unit. In zooming from a wide-angle limit to a telephoto limit at the time of image taking, at least the first lens unit and the second lens unit move in an optical axis direction, while the fourth lens unit and the fifth lens unit are each composed of one lens element.

Abstract: Provided is a zoom lens allows size reduction in the depth direction and compactness. The zoom lens includes a plurality of lens groups (GR1 to GR5) and performs zooming by changing an inter-group distance. Of the plurality of lens groups (GR1 to GR5), a first lens group (GR1) on the most object side has a positive refractive power and is fixed. A reflection member for bending an optical axis is provided in the first lens group (GR1) and the reflection member is formed of a rectangular prism (P) having a negative refractive power. In addition, an imaging apparatus using the zoom lens is provided.

Abstract: A variable-power optical system includes, in order from an object side, first to fifth lens groups. The first and third lens groups are fixed at a time of varying magnification and at a time of focusing. The second, fourth and fifth lens groups are movable at the time of varying magnification. The first, third and fourth lens groups have positive refractive powers. The second and fifth lens groups have negative refractive powers. The fourth lens group has a focusing function. The following conditional expressions are satisfied. 0.4<fw/f1<0.8 0.5<|f2/fw|<0.8 where fw denotes a focal length of the whole system at an wide end, f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group.

Abstract: In a zoom lens ZL1 having a plurality of lens groups G1 to G2 which are disposed in order from an object, where a refractive index average value of the lens components which constitute the zoom lens ZL1 is defined as ndav and a refractive index average value of the lens components which constitute the first lens group G1 which is disposed to closest to the object among the plurality of lens groups G1 to G2 is defined as ndGlav, the zoom lens ZL1 is constituted to satisfy the conditional expression ndav?1.80 and to satisfy the conditional expression ndGlav?1.85.

Abstract: A zoom lens having a plurality of lens groups which performs zooming by changing distances between groups includes a reflective member to bend an optical axis which passes through the plurality of the lens groups. The plurality of lens groups includes, in order from an object side to an image plane side: a first lens group having a positive refractive power and fixed in position; a second lens group having a negative refractive power and to be moved along the optical axis direction when zooming; a third lens group having a positive refractive power and fixed in position; a fourth lens group having a positive refractive power and to be moved in the optical axis direction to compensate a position change of the image plane when zooming and focusing; and a fifth lens group having a negative refractive power and fixed in position when zooming.

Abstract: A zoom lens with a reduced thickness and size in the depthwise direction consists of a plurality of lens groups (GR1 to GR5), so that it varies in power in response to variation in intervals between the lens groups. The zoom lens also has a prism G2 to bend the optical axis passing through the lens groups (GR1 to GR5). The last lens group G5 (counted from the object side) is composed of a negative lens group and a positive lens group, with an air layer interposed between them (arranged sequentially from the object side). The present invention also provides an imaging device equipped with an imaging element to convert the optical images formed by said zoom lens into electrical signals.

Abstract: Disclosed is a zoom lens which is composed of a plurality of groups of lenses and which varies the power thereof by changing inter-group spacings. The zoom lens is configured such that: the last group of lenses that is located at the end of an image space and is negatively refractive is held stationary in optical-axis directions during variation of the power of the zoom lens, and includes a front group of negative lenses and a rear group of positive lenses; and the rear group of positive lenses or part of the rear group of positive lenses (hereinafter, referred to as a group of blur compensation lenses) is movable in directions orthogonal to the optical axis of the zoom lens. In this configuration, the group of blur compensation lenses is moved in the directions orthogonal to the optical axis in order to shift an image.

Abstract: A zoom lens having five lens groups arranged in succession. The zoom lens is configured such that when zooming from a short focal length end toward a long focal length end, the second lens group lens moves toward the third lens group and the fourth lens group moves toward a side of the third lens group, and the fifth lens group corrects the zooming and a shift in a position of an imaging plane of the zoom lens caused by movement of the third lens group and the fourth lens group.

Abstract: A zoom lens is proposed, which includes a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, which are arranged in order from an object side, performing zooming by moving the second lens group and the fourth lens group, wherein the first lens group includes a front lens group having negative refractive power, an optical member refracting a light path, and a rear lens group having positive refractive power, which are arranged in order from the object side, wherein the fourth lens group includes one single lens, and if an image forming power of the fifth lens group at an object distance of infinity is ?5, a conditional formula (1) 1.0<?5<1.8 is satisfied.

Abstract: By reducing the outer diameter, increasing the overall length, and correcting chromatic aberration well, the invention realizes an objective optical system and examination apparatus that are suitable for in-vivo examination with a sufficiently increased length and widened observation range. The invention provides a compact objective optical system and an examination apparatus comprising, in order from an object side: a first lens group having positive power; a second lens group including a compound lens; a third lens group formed of a biconvex lens; a fourth lens group having positive power and including a compound lens; and a fifth lens group having positive power. Joining surfaces of the compound lens included in the second lens group and the compound lens included in the fourth lens group have negative power.

Abstract: Disclosed are a zoom lens and an imaging device. The zoom lens has a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, a fourth lens group with positive refractive power, and a fifth lens group including a negative subgroup with negative refractive power and a positive subgroup and with positive refractive power. An aperture stop is disposed in the vicinity of the third lens group. The lens surface of the negative subgroup of the fifth lens group on the image side and nearest to the image is concave, and the lens surface of the positive subgroup of the fifth lens group on the object side and nearest to the object is convex. The positive subgroup shifts in a direction approximately perpendicular to the optical axis to shift an image. The zoom lens satisfies the condition defined by the inequality (1) below: 0.2<f5p/ft<0.

Abstract: A zoom lens system, in sequence from an object side to an image side, includes a first lens group having positive refractive power and fixed for gathering incoming light; a second lens group having negative refractive power for changing a focal length of the zoom lens system; a third lens group having positive refractive power and made stationary; a fourth lens group having positive refractive power and movable for compensating for a fluctuation of an image plane position; and a fifth lens group having positive refractive power and movable for focusing purpose. During zooming from a wide-angle end to a telephoto end, the second and fourth lens groups are moved independently toward the third lens group in such a manner that spacing between the first lens group and the second lens group increases and spacing between the third lens group and the fourth lens group decreases.

Abstract: A compact, lightweight, and high-performance lens and method of using the same are provided. In one embodiment, the lens includes a crown glass having a first aspheric surface, a flint glass optically coupled to the crown glass, the first flint glass having a second aspheric surface, and an air gap between the crown glass and the flint glass.

Abstract: An afocal zoom lens for microscopes includes five lens units having, in order from the object side, positive, negative, negative, positive, and negative refracting powers. When the magnification of the afocal zoom lens is changed in the range from a low-magnification position to a high-magnification position, a first lens unit and a fifth lens unit are fixed, a second lens unit is moved toward the image side, and a fourth lens unit is moved toward the object side. The afocal zoom lens satisfies the following condition: 0?F2/F3?2.5 where the focal length of the second lens unit is represented by F2 and the focal length of a third lens unit is represented by F3. The third lens unit is constructed with at least one negative lens with a concave surface facing the object side.

Abstract: A projection objective includes a first lens group (G1) of positive refractive power, a second lens group (G2) of negative refractive power and at least one further lens group of positive refractive power in which a diaphragm is mounted. The first lens group (G1) includes exclusively lenses of positive refractive power. The number of lenses of positive refractive power (L101 to L103; L201, L202) of the first lens group (G1) is less than the number of lenses of positive refractive power (L116 to L119; L215 to L217) which are mounted forward of the diaphragm of the further lens group (G5).

Abstract: An improved electronic camera is disclosed which enables higher light-detecting efficiency of the electronic image pick-up device and reduces focusing errors in the periphery of the image field. The present invention arranges the detectors of an optical pick-up device on a surface that is non-planar. In this way, the surface of the optical pick-up device can be made to correspond with the actual image surface of the camera optical system. Further, each detecting element of the optical pick-up device is illuminated by light rays that are normal to its surface, thereby increasing the light detecting efficiency of the optical pick-up device in the periphery of the image field while decreasing focusing errors that occur at the periphery of the image field.