Abstract: A lens attachment, used with an objective lens, including from object side to image side, a first lens element with positive power, a second lens element with negative power, a third lens element with positive power, a fourth lens element with negative power, and a fifth lens element with positive power; the second and third lens elements form a doublet by adhesive; at least two of the third, fourth and fifth lens elements are anomalous dispersion lenses.

Abstract: A rear attachment lens according to the aspect of the embodiments is configured to vary a focal length of a system by being attached to an image side of a master lens. The rear attachment lens includes a positive lens arranged closest to the image side in which a lens surface on the image side of the positive lens has a shape convex toward the image side. A focal length of the rear attachment lens, a magnification of the rear attachment lens when attached to the master lens, and a distance from the lens surface on the image side of the positive lens to a rear principal point position of the rear attachment lens when attached to the master lens are appropriately set.

Abstract: The invention relates to a measurement system for optically measuring an object, comprising a dental camera and an optical attachment. In this case the optical attachment comprises at least one lens, which is shaped and arranged in such a way that the optical attachment has a negative focal length so that a measurement field or a measurement volume of the dental camera is enlarged by the optical attachment.

Abstract: The rear converter lens consists of, in order from an object side: a first lens group that has a positive refractive power; a second lens group that has a negative refractive power; and a third lens group that has a positive refractive power. The first lens group consists of a cemented lens in which a negative lens concave toward the image side and a positive lens convex toward the object side are cemented. The second lens group consists of a cemented lens in which a negative lens concave toward the image side, a positive lens convex toward both sides, and a negative lens concave toward the object side are cemented. The third lens group consists of a cemented lens in which a positive lens convex toward the object side and a negative lens are cemented. The rear converter lens satisfies predetermined Conditional Expressions (1) and (2).

Abstract: A lens assembly comprises sequentially from an object side to an image side along an optical axis a first lens, a second lens, a third lens, a stop, a fourth lens, a fifth lens and a sixth lens. The first lens is a meniscus with refractive power and includes a convex surface facing an object side and a concave surface facing an image side. The second lens is with negative refractive power and includes a concave surface facing the object side. The third lens is with positive refractive power and includes a convex surface facing the image side. The fourth lens is with positive refractive power and includes a convex surface facing the image side. The fifth lens is a biconcave lens with negative refractive power. The sixth lens is with positive refractive power and includes a convex surface facing the object side.

Abstract: The rear attachment lens has a positive refractive power as a whole, and is attached to an image side of a main lens so as to change a focal length of the whole lens system after attachment to a focal length longer than a focal length of the main lens. The rear attachment lens includes a most object side lens that is a lens which has a negative refractive power and is disposed to be closest to an object side, and a most image side lens that is a lens which has a positive refractive power and is disposed to be closest to the image side.

Abstract: An image pickup apparatus includes: a mount to which an interchangeable lens is mountable; an image sensor; an optical system having a refractive power and imaging an object point located on an image side of a most-object-side surface of the optical system onto the image sensor; and an optical filter arranged between the optical system and the image sensor, and a distance on an optical axis from a flange surface of the mount to the object point located on the image side of the most-object-side surface, a distance on the optical axis from the flange surface of the mount to the image pickup element, and a lateral magnification of the optical system when the interchangeable lens is mounted to the image pickup apparatus and the object point located on the image side of the most-object-side surface, is imaged onto the image pickup element, are appropriately set.

Abstract: Provided is a rear converter optical system which is detachably mounted on an image side of a main lens system to increase a focal length of the main lens system, in which an effective diameter ?im of an imaging area of the main lens system, an effective diameter ?cr of a lens surface closest to the image side of the rear converter optical system, a lateral magnification ?c of the rear converter optical system in the case where the rear converter optical system is mounted on the main lens system, a backfocus skc in the case where the rear converter optical system is mounted on the main lens system are appropriately set.

Abstract: An optical lens includes a first lens group with a negative refractive power, an aperture stop, and a second lens group with a positive refractive power. The first lens group includes a first aspheric lens and a second aspheric lens. The optical lens satisfies the conditions: 3.5>RT1>2.5 and 3.5>RT2>2.6, where RT1 is a ratio of a maximum axial thickness to a minimum axial thickness within a clear aperture of the first aspheric lens, and RT2 is a ratio of a maximum axial thickness to a minimum axial thickness within a clear aperture of the second aspheric lens.

Abstract: In a hydraulic cylinder piston unit comprising a cylinder with an interior space delimited by opposite end walls in which a piston and a compensation seal element are movably arranged supported by a piston rod and engaged by a compensation spring disposed between the compensation seal element and an adjacent cylinder end wall, the compensation seal element has two spaced seal rings via which it is guided along the inner cylinder wall and the compensation spring is supported directly on the compensation seal element for an improved sealing effect of the compensation seal element in the extended state of the hydraulic cylinder piston unit and a simplified design.

Abstract: The invention relates to a measurement system for optically measuring an object, comprising a dental camera and an optical attachment. In this case the optical attachment comprises at least one lens, which is shaped and arranged in such a way that the optical attachment has a negative focal length so that a measurement field or a measurement volume of the dental camera is enlarged by the optical attachment.

Abstract: A conversion lens having a negative refractive power includes a positive lens GP. The positive lens GP satisfies all the following conditional expressions: 30??d?40, 1.225?[nd?(14.387/?d)]?1.276, and 0.4300?[?gF?(2.9795/?d)]?0.5010, where ?d is an Abbe number of the positive lens GP, ?gF is a partial dispersion ratio of the positive lens GP for g-line and F-line, and nd is a refractive index of the positive lens GP for d-line.

Abstract: Communication devices for communicating using EHF electromagnetic radiation that include a dielectric lens configured to refract incident EHF electromagnetic radiation. The communication device may include an integrated circuit (IC) package that in turn includes a transducer configured to transmit and/or receive an EHF electromagnetic signal and convert between electrical signals and electromagnetic signals. The integrated circuit package also includes an integrated circuit including at least one of a transmitter circuit and a received circuit that is operatively coupled to the transducer. The dielectric lens is generally disposed so as to enhance transmission or reception of the EHF electromagnetic signal by the transducer.

Abstract: Provided are a rear converter lens and an imaging apparatus capable of achieving favorable optical performance and an appropriate back focal length with high magnification. The rear converter lens RCL consists of, in order from the object side, four lens-groups of positive, negative, negative, and positive lens-groups. In order from the object side, a first lens-group RG1 consists of a negative lens RL11 and a positive lens RL12, a second lens-group RG2 consists of a negative lens RL21 and a positive lens RL22, a third lens-group RG3 consists of a negative lens RL31, a positive lens RL32, and a negative lens RL33, and a fourth lens-group RG4 consists of a biconvex lens RL41 and a negative lens RL42. Here, 0.22<cf/f12<1 is satisfied, where f12 is a composite focal length of the first lens-group RG1 and the second lens-group RG2, and cf is a focal length of the rear converter lens RCL.

Abstract: A partial lens unit St includes one or more positive lenses that are appropriately set based on a focal length f1 of a first lens unit, a focal length f2 of a second lens unit, an overall lens length L, a focal length f of an imaging optical system of when focused on an infinite-distance object, a focal length fPi of an i-th positive lens in an i-th position, among the positive lenses, counted in order from an object side to an image side, an Abbe number and an anomalous partial dispersion ratio difference ?dPi and ??gFPi of a material for the i-th positive lens, and the total number n of the positive lenses included in the one or more partial lens units St.

Abstract: An image pickup apparatus includes: a mount to which an interchangeable lens is mountable; an image sensor; an optical system having a refractive power and imaging an object point located on an image side of a most-object-side surface of the optical system onto the image sensor; and an optical filter arranged between the optical system and the image sensor, and a distance on an optical axis from a flange surface of the mount to the object point located on the image side of the most-object-side surface, a distance on the optical axis from the flange surface of the mount to the image pickup element, and a lateral magnification of the optical system when the interchangeable lens is mounted to the image pickup apparatus and the object point located on the image side of the most-object-side surface, is imaged onto the image pickup element, are appropriately set.

Abstract: A lens barrel which is capable of increasing zoom rate and slimming down a lens barrel, and by extension an image pickup apparatus while reducing the size of the lens barrel in a radial direction without decreasing the lens diameter of a retractable lens which retracts outwardly in a radial direction when the lens barrel is collapsed. A first lens holding frame holds a first lens, and a second lens holding frame holds a second lens. The first lens holding frame follows a cam groove, which is formed in a cam cylinder, to move in a direction of an optical axis. In a shooting state, the second lens is disposed on the optical axis. In a retracted state, the second lens is disposed at a position retracted outwardly in a radial direction from the center of the optical axis and on a rear surface of the cam cylinder.

Abstract: A rear attachment lens changes a focal-length of an entire lens-system, in which the rear attachment lens has been attached to a main-lens, to a longer focal-length-side than a focal-length of the main-lens by being attached to an image-side of the main-lens. The rear attachment lens consists essentially of a first-lens-group and a second-lens-group in this order from an object-side. The first-lens-group consists essentially of a negative lens and a positive lens in this order from the object-side. The second-lens-group consists essentially of at least one negative lens and at least one positive lens, and a lens closest to an image-side in the second lens-group is a positive lens. When an Abbe number for d-line and a partial dispersion ratio between g-line and F-line of the negative lens in the first-lens-group are ?d1 and ?gF1, respectively, conditional expression (1): ?d1>62 and conditional expression (2): 0.64<?gF1+0.001625 ×?d1<0.69 are satisfied.

Abstract: The invention comprises a method for configuring an imaging apparatus having an image sensor and an optical assembly. The method modifies a first imaging configuration of the imaging apparatus to achieve a second imaging configuration of said imaging apparatus, by interposing a refractive optical element between an image-side surface of the optical assembly and an imaging surface. In another embodiment, the method modifies a first imaging configuration of the imaging apparatus to achieve a second imaging configuration of said imaging apparatus by removing the refractive optical element from between an image-side surface of the optical assembly and an imaging surface. The invention additionally includes an imaging apparatus configured for switching from a first imaging configuration to a second imaging configuration. At least one of the first imaging configuration and the second imaging configuration may be configured for iris imaging.

Abstract: An image-reading lens includes front-group and rear-group lens systems which are arranged on an object side and an image side, respectively. The front-group lens system includes equal to or less than 5 lenses which include at least one positive lens and at least one negative lens, and the rear-group lens system includes one negative lens. An angle of view of an entire system of the image-reading lens is equal to or more than 56°. The front-group and rear-group lens systems are structured such that with respect to a change in a distance between the front-group and rear-group lens systems, a change in a focal length of the entire system of the image-reading lens is small, and a change in an image plane is large, and by adjusting the distance between the front-group and rear-group lens systems, a required lens performance is obtained.

Abstract: An image capture device and a converter lens assembly thereof are provided. The image capture device includes a mobile phone and the converter lens assembly wherein the converter lens assembly is connected to the mobile phone. The converter lens assembly includes a first lens, a second lens, a third lens, a fourth lens and a fifth lens, all of which are arranged in sequence from an object side to an image side along an optical axis. The first lens is with positive refractive power. The fourth lens is with positive refractive power. The converter lens assembly satisfies the condition: 1<|f1/f2|<2 and/or the condition: 1<|f345/f2|<2, wherein f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f345 is the effective focal length of the combination of the third lens, the fourth lens and the fifth lens.

Abstract: Provided is a camera apparatus including a lens apparatus which is attachable thereto and detachable therefrom, the camera apparatus including: an optical system; and an optical element which is insertable to and removable from an optical path of the optical system, in which: the optical element includes a surface having positive refractive power; and the optical system includes a surface having negative refractive power.

Abstract: Provided is an adapter optical system attachable between an image pickup lens and a camera body, the adapter optical system including, in order from an object side: a first optical unit having negative refractive power; a second optical unit that is insertable in and removable from an optical path; and a third optical unit having positive refractive power, in which the following expression is satisfied: 0.03<|?2|<0.50, where ?a2 represents an incident converted inclination angle obtained by normalizing an incident inclination angle of an axial beam entering the second optical unit inserted in an optical path with an exit inclination angle of an axial paraxial ray emerging from a surface closest to an image plane side in the adapter optical system being set to one (1).

Abstract: A lens barrel is provided that includes a zoom optical system with an optical axis. The lens barrel also includes a first and a second lens group. The first lens group has a first curved part and a first straight part when viewed axially along the optical axis. The second lens group is axially and movably disposed relative to the first lens group and has a second curved part and a second straight part when viewed axially along the optical axis. The lens barrel is configured to change between an imaging state and a retracted state. In the imaging state, the first and second lens groups are aligned with one another along the optical axis. In the retracted state, the second lens group is disposed off center from the first lens group so that the first straight part is substantially parallel with the second straight part.

Abstract: A teleconverter lens system is attachable to or detachable from an object side of a main lens system and facilitates performing telephotographing. A photographing apparatus includes the teleconverter lens system. The teleconverter lens system includes: a first lens having a negative refractive power; a second lens having a positive refractive power; a third lens having a negative refractive power; and a fourth lens having a positive refractive power, wherein the first, second, third, and fourth lenses are sequentially arranged from an object side to an image side of the teleconverter lens system. The first and second lenses are cemented together, and the second lens has a meniscus shape in which a convex surface is formed on the object side of the second lens.

Abstract: A rear attachment lens detachably attached to a main lens system at an image side thereof to lengthen a focal length includes a negative lens disposed such that, when L is a distance between a lens surface closest to an object side and a lens surface closest to an image side in the rear attachment lens, the negative lens is within an area in which a distance from the lens surface closest to the object side to the negative lens is in the range of 0.5 L to 1.0 L. When ?dn1 is an Abbe number of a material of the negative lens with respect to the d-line and ?gFn1 is a partial dispersion ratio of the material of the negative lens with respect to the g-line and the F-line, the following conditions are satisfied: 10<?dn1<23 0.020<?gFn1?0.6438+0.001682*?dn1<0.100.

Abstract: A lens unit is equipped with a lens, through which light from an object enters, and a lens barrel for holding the lens. An optical extending member is employed when observing a focal image of the lens with a microscope. A receiving portion having a receiving surface, for receiving a front end facet of the optical path extending member within the lens barrel that faces toward the lens, is formed at a portion of the lens barrel. A mounting portion positioned further rearward from a rear end facet of the optical path extending member, having a guide insertion aperture that extends in a direction perpendicular to the receiving surface and a mounting surface that extends in a direction parallel to the receiving surface is formed at the periphery of the guide insertion aperture is formed at a portion of the lens barrel.

Abstract: A relay lens is used for an imaging system having a main lens. The main lens has a pupil plane. The relay lens, in the order from the subject side to the image side thereof, includes a first lens of negative refractive power, and a second lens of positive refractive power. The first lens has a first principle plane and a second principle plane. The second lens has a third principle plane and a fourth principle plane. The relay lens system satisfies the following formulas: 0.53<|ƒ1/ƒ2|<0.57; 1.54<?1/?2<3.11; 0.22<D1/D2<0.65, where f1 and f2 are the effective focal lengths of the first and second lenses, v1 and v2 are the Abbe numbers of the first and second lenses, D1 is the distance between the second principle plane and the third principle plane, D2 is the distance between the fourth principle plane and the pupil plane.

Abstract: A rear attachment lens detachably attached to an image side of a main lens system to change a focal length of an entire system so as to become longer than a focal length of the main lens system includes one or more positive lenses GMp. One among the one or more positive lenses GMp is a positive lens P1. The Abbe number, a partial dispersion ratio, and a partial dispersion ratio difference of a material of the one or more positive lenses GMp and of the positive lens P1, and a focal length of the positive lens P1 are correctly defined so that chromatic aberrations are appropriately corrected, when predetermined conditions are satisfied.

Abstract: A rear attachment lens detachably attached to an image side of a main lens system to change a focal length of an entire system so as to become longer than a focal length of the main lens system includes one or more positive lenses GMp. One among the one or more positive lenses GMp is a positive lens P1. The Abbe number, a partial dispersion ratio, and a partial dispersion ratio difference of a material of the one or more positive lenses GMp and of the positive lens P1, and a focal length of the positive lens P1 are correctly defined so that chromatic aberrations are appropriately corrected, when predetermined conditions are satisfied.

Abstract: A rear attachment lens detachably attached to a main lens system at an image side thereof to lengthen a focal length includes a negative lens disposed such that, when L is a distance between a lens surface closest to an object side and a lens surface closest to an image side in the rear attachment lens, the negative lens is within an area in which a distance from the lens surface closest to the object side to the negative lens is in the range of 0.5L to 1.0L. When ?dn1 is an Abbe number of a material of the negative lens with respect to the d-line and ?gFn1 is a partial dispersion ratio of the material of the negative lens with respect to the g-line and the F-line, the following conditions are satisfied: 10<?dn1<23 0.020<?gFn1?0.6438+0.001682*?dn1<0.100.

Abstract: A lens barrel includes: a lens frame retaining at least one portion of the plurality of lens groups; a first lens cylinder supporting the lens frame inside thereof and including a plurality of cam followers on an outer circumferential section thereof; and a second lens cylinder including a mutually parallel plurality of cam grooves in an inner circumferential section thereof and storing the first lens cylinder therein in the collapsed state, the plurality of cam grooves are engaged with the plurality of cam followers and configured to advance and retire the first lens cylinder in a direction of an optical axis by a relative rotation of the first lens cylinder, the plurality of cam grooves have a first cam grooves and a second cam grooves, the plurality of cam followers have a first cam follower and a second cam follower, the first cam follower and the second cam follower are engaged with the first cam grooves and the second cam grooves, respectively, and the first cam follower and the second cam follower are

Abstract: The extender lens apparatus is detachably attached to an image-forming optical system including a first main lens unit disposed closest to an object and a second main lens unit disposed between the first main lens unit and an image plane. The apparatus includes a first extender lens unit to be inserted in a space closer to the first main lens unit than the second main lens unit, and a second extender lens unit to be inserted in a space closer to the image plane than the second main lens unit. The first extender lens unit has a magnification increasing effect. The apparatus is capable of varying a magnification of the image-forming optical system while maintaining good optical performance without greatly increasing the entire length of the image-forming optical system.

Abstract: A switchable magnification lens used to vary the magnification of an image going to be captured by a camera. The switchable magnification lens includes an outer barrel and a switchable magnification unit detachably arranged in the outer barrel and connected to the zoom lens. The image will be magnified while passing through the switchable magnification unit from a first end to a second end, and the image will be shrunk while passing through the switchable magnification unit from the second end to the first end. The switchable magnification unit is able to change its orientation with respect to the outer barrel. The image will be magnified while the first end is away from the camera and the second end is toward the camera, and the image will be shrunk while the first end is toward the camera and the second end is away from the camera.

Abstract: A zoom lens includes, in order along an optical axis from a side nearest to a photographic subject to an imaging site, a first lens group I that comprises a positive refraction index and is anchored in place when performing a magnification of an image, a second lens group II that comprises a negative refraction index, a third lens group III that comprises a positive refraction index, a fourth lens group IV that comprises a positive refraction index, a fifth lens group V that comprises a negative refraction index, and a sixth lens group VI that comprises a positive refraction index, wherein, when magnifying from a wide angle end to a telephoto end, the magnification thereof is performed by moving the second lens group II, the fourth lens group IV, and the fifth lens group V, at a minimum, the first lens group I comprises a reflective optical element, which is for refracting a light path therein, an additional lens group VII, comprising a negative refraction index, is interposed between the lens groups of the z

Abstract: A retractable lens barrel achieving thinning thereof in both directions parallel and perpendicular to a photographic optical axis. The lens barrel has a first lens and a second lens disposed in an inside thereof, and has a structure in which an optical axis of the second lens is aligned with an optical axis of the first lens when photographing, and the first lens is moved to a housed position and the second lens is moved in a retreating direction from the optical axis of the first lens when the first and second lenses are retracted. The lens barrel also has a holding member for holding the second lens and a rotation unit for rotating the holding member of the second lens, the holding member being rotated about a rotation shaft different from the optical axis of the first lens and perpendicular to the optical axes of the first and second lenses.

Abstract: The invention relates to a rear converter lens apparatus to obtain a lens system having a focal length longer than that of a master lens device by the mounting of the master lens device, and a taking system comprising the same. A converter lens portion consists of, in order from an object side that is the master lens device side, a first lens group of positive refracting power, a second lens group of positive refracting power and a third lens group of negative refracting power. Between the respective lens groups there is a spacing. The first and second lens groups are located such that of axial air spaces in the converter lens portion, an air space between the first lens group and the second lens group is largest. One each lens group comprises a positive lens element and a negative lens element.

Abstract: A multi-magnification viewing and aiming scope includes a first imaging group including an objective lens lying on the optical path and an eyepiece lens lying on the optical path. The first imaging group forms a first image having a first magnification on the optical path at an image location. A second imaging lens group may be controllably inserted into the optical path between at least some elements of the objective lens and the eyepiece lens. Upon insertion of the second imaging lens group into the optical path an optical combination of the first imaging group and the second imaging lens group forms a second image having a second magnification on the optical path at substantially the image location. The insertion may be accomplished by a tumbler mechanism upon which the second imaging lens group is mounted. The tumbler mechanism controllably pivots the second imaging lens group about a tumbler axis perpendicular to the optical path, between inserted and non-inserted positions.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and a rear lens group which is provided on the image side of the negative second lens group, and has a combined positive refractive power, in this order from the object; and the zoom lens system satisfies the following conditions: 5.0<f1/fw<6.5 ??(1) 0.4<fRt/ft<0.55 ??(2) wherein f1 designates a focal length of the positive first lens group; fw designates a focal length of the entire the zoom lens system at the short focal length extremity; fRt designates a combined focal length of the positive rear lens group at the long focal length extremity; and ft designates a focal length of the entire zoom lens system at the long focal length extremity.

Abstract: A projection objective of a microlithographic projection exposure apparatus has a last optical element on the image side which is plane on the image side and which, together with an image plane of the projection objective, delimits an immersion space in the direction of an optical axis of the projection objective. This immersion space can be filled with an immersion liquid. At least one liquid or solid volume having plane-parallel interfaces can be introduced into the beam path of the projection objective, the optical thickness of the at least one volume being at least substantially equal to the optical thickness of the immersion space. By introducing and removing the volume, it is possible to convert the projection objective from dry operation to immersed operation in a straightforward way, without extensive adjustments to the projection objective or alignment work.

Abstract: A focus adjustable optical system includes a first lens unit and a second lens unit arranged on an optical axis in direction from the object side to the image side. The two opposite surfaces of each of the lenses of the first lens unit and second lens unit are non-spherical surfaces. Each lens of the first lens unit defines with the image side a fixed distance. The second lens unit has one lens movable by a low-power small-sized driving source along the optical axis to adjust its distance relative to the image side and to further adjust the focal distance while the distance between the first lens unit and the image plane remains unchanged.

Abstract: A method of adjusting a projection objective permits the projection objective to be adjusted between an immersion configuration and a dry configuration with few interventions in the system, and therefore to be used optionally as an immersion objective or as a dry objective. The projection objective has a multiplicity of optical elements which are arranged along an optical axis of the projection objective, the optical elements comprising a first group of optical elements following the object plane and a last optical element following the first group, arranged next to the image plane and defining an exit surface of the projection objective which is arranged at a working distance from the image plane. The last optical element is substantially without refracting power and has no curvature or only slight curvature.

Abstract: An optical system includes a primary lens group having a central beam path therethrough and including a front lens group and a rear lens group. An anamorphic lens group lies on the central beam path and is positioned between the front lens group and the rear lens group. The anamorphic lens group includes at least one optically powered anamorphic lens that has different enlargements of a light beam along different axes perpendicular to the central beam path. The anamorphic lens group may be mounted on structure that allows it to be removed from the central beam path. An image transceiver is either an image source that directs a light beam through the primary lens group and the anamorphic lens group, or is an image receiver that receives a light beam through the primary lens group and the anamorphic lens group.

Abstract: A zoom lens in which a precise focus detection signal can be detected while a user can observe an image to be shoot without being affected by insertion/removal of an extender lens into an optical axis. A relay lens unit stationary during zooming includes lens unit L21 including a branch element, lens unit L22 interchangeable with extender lens unit insertable into/removable from optical path to change focal length range of the entire system and positive lens unit L23 in order from object side to image side, and the zoom lens satisfies specific conditions among distance from an aperture stop to front principal point of L21, distance from rear principal point of L21 to front principal point of L22, distance from rear principal point of L22 to front principal point of L23, refractive power of L21, and refractive power of the entire system of the zoom lens at wide-angle end.

Abstract: A method of adjusting a projection objective permits the projection objective to be adjusted between an immersion configuration and a dry configuration. The projection objective includes optical elements arranged along an optical axis thereof, which include a first group of elements following the object plane and a last optical element following the first group, which is arranged near the image plane. The last optical element defines an exit surface of the projection objective, which is arranged at a working distance from the image plane. The last optical element is substantially without refracting power and has no or only slight curvature. The method includes varying the thickness of the last optical element, changing the refractive index of the space between the exit surface and the image plane by introducing or removing an immersion medium, and axially displacing the last optical element to set a working distance.

Abstract: A converter lens includes a front unit and a rear unit disposed on an image side with respect to the front unit. The front unit has positive optical power and includes two positive lens elements. The two positive lens elements are spaced apart. The rear unit has negative optical power and includes a positive lens element and a negative lens element.

Abstract: A zoom lens includes first to fourth lens units arranged in order from an object, respectively. The first lens unit is fixed during power-varying and has positive optical power. The second lens unit is movable during power-varying. The third lens unit is movable so as to compensate image-plane fluctuation in accordance with the power-varying. The fourth lens unit is fixed during the power-varying and has positive optical power. The first lens unit includes a first lens subunit having positive optical power, and a second lens subunit having negative optical power, arranged in order from the object, respectively. One of the first and second lens subunits moves upon focus adjustment. Further, the following conditions are satisfied: ?2.5<f1b/f1a<?0.6 and 0.2<f1/fT<0.8. Wherein f1, f1a, f1b, and fT respectively represent the focal lengths of the first lens unit, the first lens subunit, the second lens subunit, and the overall system of the zoom lens at its telephoto end.

Abstract: To obtain an anamorphic converter of the rear converter system which is especially most suitable for a converter for the cinema and excellent in optical performance, and in which an effective image surface of an imaging optical system can be sufficiently utilized. The anamorphic converter includes at least an anamorphic lens disposed on an image side of an imaging optical system, and in the anamorphic converter, when a focal length conversion magnification in an arbitrary cross section X containing an optical axis of the anamorphic converter is assigned ?x, a focal length conversion magnification in a cross section Y containing an optical axis and being perpendicular to the cross section X is assigned ?y, an aspect ratio of an image pickup range in an image surface of the imaging optical system is assigned AR1, and an aspect ratio of an effective area of image pickup means is assigned AR2, the following relationship is established: 0.9<(AR1×?x)/(AR2×?y)<1.1.

Abstract: An optical magnification adjustment system being capable of minutely correcting magnification. A first lens 1 of plano-convex is installed on the side of an object surface 5, and a second lens 2 of concave-plano is installed on the side of a formed image surface 7. By controlling the center space d between the first lens and the second lens, the image is enlarged or reduced. The radii of curvature R2 and R3 of the convex surface of the first lens and the concave surface of the second lens are respectively set according to the following equations. R2=(1−n1)/&phgr;2 R3=(n2−1)/&phgr;3 where, &phgr;2 and &phgr;3 represent optical power, and n1 and n2 represent refraction indexes, respectively.

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.