Abstract: A variable magnification optical system comprising, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a rear lens group having negative refractive power; upon varying a magnification from a wide angle end state to a tele photo end state, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the rear lens group being varied; the third lens group or the rear lens group comprising a focusing lens group which is moved upon carrying out focusing from an infinitely distant object to a closely distant object; and predetermined conditional expression(s) being satisfied, thereby various aberrations being corrected superbly.

Abstract: Provided are an imaging controller, an operation method and program of the imaging controller, and a camera capable of presenting a radiation image of a subject to a user in an easy-to-understand manner. An image sensor driving control unit causes an image sensor to image a visible ray to acquire a first image including a reflected image of a subject. The image sensor driving control unit causes the image sensor to image an infrared ray to acquire a second image including the reflected image and a radiation image of the subject. A zoom lens driving control unit moves a zoom lens along an optical axis to correct a difference in angle of view between the first image and the second image. Image processing units output difference images between the first image and the second image acquired in a state in which the difference in angle of view is corrected.

Abstract: A facial recognition method includes receiving, by an electronic device, a first instruction triggering the electronic device to perform facial recognition, emitting in response to the first instruction, infrared light with a light spot using an infrared projector, collecting first image information of a first object using a first camera, collecting second image information of the first object using a second camera, calculating depth information of the first object based on the first image information, the second image information, the first length, a lens focal length of the first camera, and a lens focal length of the second camera, and performing user identity verification on the first object using the first image information and the depth information of the first object.

Abstract: An optical system includes a first lens unit having a positive refractive power disposed closest to an object, a first focus lens unit having a positive refractive power disposed on an image side of the first lens unit, and a second focus lens unit having a negative refractive power disposed on the image side of the first focus lens unit. The first lens unit is fixed during focusing. The first focus lens unit and the second focus lens unit are movable during focusing so that a distance between the first focus lens unit and the second focus lens unit changes. The first lens unit includes a single negative lens disposed closest to the object. A predetermined condition is satisfied.

Abstract: An information processing device includes a processor configured to operate an operation target according to a first operation mode on a basis of biological information about a user, and operate the operation target according to a second operation mode different from the first operation mode on a basis of the biological information about the user in a case where biological information about the user is being measured and the operation target is not operated according to the first operation mode on the basis of the biological information about the user for a predetermined time or longer.

Abstract: A zoom lens includes, in order from an object side to an image side, a first lens unit having a positive refractive power, a second lens unit having a negative power, and a rear unit having a positive refractive power as a whole and including one or more lens units. A distance between adjacent lens units changes during zooming. The first lens unit includes a first subunit having a positive refractive power and a second subunit disposed on the image side of the first subunit. The first subunit includes a first positive lens having the smallest absolute value of a focal length among lenses included in the first subunit. The second subunit includes a second positive lens and a first negative lens having the smallest absolute value of a focal length among negative lenses included in the second subunit. A predetermined condition is satisfied.

Abstract: A lens apparatus includes two optical systems each of which includes, in order from an object side to an image side, a negative first lens unit, a first reflective member, an aperture diaphragm, a second reflective member, and a positive second lens unit. Each optical system satisfies following inequalities: 5.9<DR/f<13.6 0.7<D2/f2<5.2 10.4<DP/f<19.8 DR represents a distance on an optical axis from a reflective surface of the first reflective member to a reflective surface of the second reflective member. f represents a focal length of the optical system. f2 represents a focal length of the second lens unit. D2 represents a distance on the optical axis from the reflective surface of the second reflective member to an image plane. DP represents a distance on the optical axis from the aperture diaphragm to the image plane.

Abstract: The present disclosure discloses a zoom lens assembly including, sequentially from an object side to an image side along an optical axis, a first lens group having refractive power; a second lens group having negative refractive power; a third lens group having refractive power; and a fourth lens group having refractive power. The zoom lens assembly may be continuously zoomed by changing positions of the second lens group and the third lens group along the optical axis. A total effective focal length ft of the zoom lens assembly in a telephoto state, and a total effective focal length fw of the zoom lens assembly in a wide-angle state satisfy: 1.3<ft/fw<3.3.

Abstract: Examples are disclosed relating to applying an analytical geometric projection that has been modified by an amplitude function. One example provides a computing device comprising a logic subsystem and a storage subsystem holding instructions executable by the logic subsystem to receive an image of a scene as acquired by an image sensor, apply a mapping to the image of the scene that maps pixels of the image to projected pixels on an analytical projection that is modified by an amplitude function such that the analytical projection achieves a higher zoom effect on pixels closer to a center of the image compared to pixels closer to an edge of the image, thereby obtaining a corrected image, and output the corrected image.

Abstract: A zoom lens includes a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group in order from an object side. In a case of magnification, the first lens group, the second lens group, and the third lens group move. The third lens group consists of a third a lens group that does not move in a case of image shake correction, a third b lens group that moves in the case of the image shake correction, and a third c lens group that does not move in the case of the image shake correction in order from the object side. The third b lens group consists of a positive lens and a negative lens. A predetermined conditional expression related to the third b lens group is satisfied.

Abstract: An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens sequentially disposed in ascending numerical order along an optical axis from an object side of the optical imaging system toward an imaging plane of the optical imaging system. Four or more lenses among the first to seventh lenses have a refractive index greater than 1.6.

Abstract: A dual-aperture zoom camera comprising a Wide camera with a respective Wide lens and a Tele camera with a respective Tele lens, the Wide and Tele cameras mounted directly on a single printed circuit board, wherein the Wide and Tele lenses have respective effective focal lengths EFLW and EFLT and respective total track lengths TTLW and TTLT and wherein TTLW/EFLW>1.1 and TTLT/EFLT<1.0. Optionally, the dual-aperture zoom camera may further comprise an optical OIS controller configured to provide a compensation lens movement according to a user-defined zoom factor (ZF) and a camera tilt (CT) through LMV=CT*EFLZF, where EFLZF is a zoom-factor dependent effective focal length.

Abstract: A projector assembly includes three coaxially aligned lenses and an aperture stop. The three coaxially aligned lenses include a first lens and, in order of increasing distance therefrom and on a same side thereof, a second lens and a positive meniscus lens. The first lens is a positive lens. The second lens is a negative lens. The second lens is located between the aperture stop and the positive meniscus lens. The projector assembly is one-sided telecentric at a plane proximate the positive meniscus lens.

Abstract: A variable power optical system (ZL) used for an optical apparatus, such as a camera (1), includes, in order from an object: a first lens group (G1) having positive refractive power; a second lens group (G2) having negative refractive power; a third lens group (G3) having positive refractive power; and a fourth lens group (G4) having positive refractive power. The distance between the respective lens groups changes upon zooming from the wide-angle end state to the telephoto end state. The third lens group (G3) includes: an intermediate group (G3b) constituted by a positive lens, a negative lens, a negative lens, and a positive lens; and an image side group (G3c) having negative refractive power and disposed to an image side of the intermediate group (G3b). Upon focusing, the position of the intermediate group (G3b) with respect to the image plane is fixed and the image side group (G3c) moves along the optical axis.

Abstract: A zoom lens includes, in order from an object side to an image side: a focus lens unit configured to be moved for focusing on an optical axis; a zoom lens unit configured to be moved for zooming on the optical axis; and a relay lens unit, in which an interval between each pair of adjacent lens units is changed for zooming, and the zoom lens includes an aperture stop arranged between the zoom lens unit and the relay lens unit or within the relay lens unit, the relay lens unit includes an extender lens unit insertable into and removable from an optical path of the relay lens unit, in which the extender lens unit includes a negative lens Lm which is an m-th lens from the object side in the extender lens unit and having a refractive index and an Abbe number that satisfy predetermined conditions.

Abstract: A zoom lens consists of, in order from the object side to the image side, a first lens unit having a positive refractive power and configured not to be moved for zooming, a second lens unit having a negative refractive power and configured to be moved for zooming, and a rear lens group including at least one lens unit. The first lens unit includes at least six lenses, a lens closest to the object side included in the first lens unit is a negative lens, and the zoom lens satisfies conditional expressions: ?1.65<f1n/f1<?1.10; 37<?1n<48; and 87<?pave<100, where f1n is a focal length of the negative lens, ?1n is an Abbe number of the negative lens with respect to d-line, f1 is a focal length of the first lens unit, and ?pave is an average of Abbe numbers of positive lenses included in the first lens unit with respect to d-line.

Abstract: A zoom lens includes in order from an object side to an image side, a first lens unit having a positive refractive power; a second lens unit having a negative refractive power and configured to move for zooming; and at least one lens unit configured to move for zooming. The distance between each pair of the lens units adjacent to each other is changed for zooming. The first lens unit includes a negative lens and an Abbe number and a partial dispersion ratio of the negative lens are properly determined.

Abstract: An imaging lens assembly includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element has negative refractive power. The second lens element has positive refractive power. The third lens element has positive refractive power. The fourth lens element has positive refractive power. The fifth lens element has positive refractive power. The sixth lens element has negative refractive power. The imaging lens assembly has a total of six lens elements.

Abstract: An image forming lens includes a first lens group and a second lens group. The first lens group has positive refractive power moved toward the object side when focusing from a long distance to a short distance. The second lens group has positive refractive power arranged closer to the image side than the first lens group. The second lens group includes, in order from the object side to the image side, a negative lens having a concave surface on the image side, a negative meniscus lens having a concave surface on the object side, and a positive lens. The focal length f21 of the negative lens and the focal length f22 of the negative meniscus lens satisfy the following conditional expression: (1) 0.1<f21/f22<0.5.

Abstract: An optical imaging lens including a first lens element, a second lens element, a third lens element, an aperture, a fourth lens element and a fifth lens element is provided. The first lens element is arranged to be a lens element of which refracting power being equal to 0 inverse millimeter (mm?1) in a first order from the object-side to the image-side. The second lens element is arranged to be a lens element having refracting power in a first order from the first lens element to the image-side. The third lens element is arranged to be a lens element having refracting power in a second order from the first lens element to the image-side. The fourth and fifth lens element are respectively arranged to be lens elements having refracting power in a first and a second order from the aperture to the image-side.

Abstract: A zoom lens includes, in order from the object side, a positive first lens unit not moving for zooming, a negative second lens unit moving for zooming, positive third and fourth lens units moving for zooming, and a positive fifth lens unit not moving for zooming. Intervals between adjacent ones of the first to fifth lens units change for zooming. The third lens unit consists of positive, positive, and negative lenses in order from the object side. Appropriate settings are made to the zoom lens's focal lengths at the wide angle and telephoto ends, the lateral magnifications of the second lens unit at the wide angle and telephoto ends, the focal lengths of the third lens unit and the negative lens in the third lens unit, and the average Abbe number of the positive lenses and the Abbe number of the negative lens in the third lens unit.

Abstract: Provided are an excellent vehicle-mounted camera to be used by being attached to a windshield or the like of a vehicle, a vehicle-mounted camera apparatus, and a method of supporting a vehicle-mounted camera. The vehicle-mounted camera includes a substrate, an image pickup element mounted on the substrate, an image processing circuit that is mounted on the substrate and processes a captured image by the image pickup element, a light collection optical unit that collects incident light, and a reflection unit that reflects output light from the light collection optical unit to the image pickup element. The vehicle-mounted camera further includes a casing that accommodates the substrate on which at least the image pickup element and the image processing circuit are mounted, the light collection optical unit, and the reflection unit.

Abstract: An optical system according to the present invention is an optical system comprises a first lens unit having positive refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power, arranged in order from an object side to an image side. During focusing from infinity to a closest distance, the second lens unit moves to the object side, whereby a distance between adjoining lens units is changed. The second lens unit comprises an aperture stop. The following conditional expression is satisfied: 1.0<D3/BF<3.0, where D3 is a length of the third lens unit on an optical axis, and BF is a back focus distance.

Abstract: A single-focus optical system includes a front lens unit and a rear lens unit. The front lens unit either includes a predetermined sub lens unit or includes an enlargement-side sub lens unit and a predetermined sub lens unit. The rear lens unit includes a first sub lens unit, a second sub lens unit, a third sub lens unit, and a fourth sub lens unit. The enlargement-side sub lens unit includes a negative lens component. The predetermined sub lens unit includes an enlargement-side meniscus lens component and a reduction-side meniscus lens component. The first sub lens unit includes positive lenses and a first predetermined negative lens. The second sub lens unit includes a predetermined negative lens component. The third sub lens unit includes a predetermined positive lens component. The fourth sub lens unit includes all lens components positioned on the reduction side of the predetermined positive lens component.

Abstract: In order to provide a projection lens barrel and a projection display device that are capable of correcting the optical characteristics of a plurality of lens groups, a projection lens barrel, comprising a lens optical system causing light from an image display element to be formed as a projected image on a screen, also comprises correction mechanisms that move each of at least two lens groups along an optical axis and correct the optical characteristics to be corrected, said lens groups each having different optical characteristics for correction in order to suppress reduction in image quality of a projected image caused by changes in optical characteristics caused by temperature changes in the projection lens barrel.

Abstract: The present invention discloses a micro-objective lens, comprising the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, the seventh lens group, the eighth lens group, the ninth lens group and the tenth lens group with optical axis arranged in a sequence from the left to the right; the focal length of the first lens group is negative; the second lens group belongs to doublet, in which the focal length of the first and second lens is positive and negative respectively; the focal length of the third lens group is positive; the fourth and fifth lens groups belongs to doublets, in which the focal length of the first and second lens in each group is negative and positive respectively; the focal length of the sixth lens group is positive; the focal length of the seventh and eighth lens groups is negative; the focal length of the ninth and tenth lens groups is positive.

Abstract: The zoom lens includes, in order from the object side, a first lens group that has a positive refractive power, a second lens group that has a negative refractive power, a third lens group that has a positive refractive power, a fourth lens group that has a positive refractive power and has a stop disposed to be closest to the object side. During zooming, the second lens group and the third lens group move, and the other lens groups remain stationary. The first lens group consists of, in order from the object side, two groups of cemented lenses in which a negative meniscus lens and a positive lens are cemented, and a cemented lens in which a positive lens and a negative lens are cemented. During focusing, only the cemented lens closest to the image side in the first lens group moves.

Abstract: The present disclosure provides a method and an apparatus for stretching an image. The method for stretching an image includes: selecting a corresponding stretching mode according to a mode selection parameter; generating a corresponding stretching filter group according to a stretching parameter and the selected stretching mode, and segmenting input image data into blocks; and processing the input image data segmented into blocks by the stretching filter group, to obtain stretched image data.

Abstract: Provided is an interchangeable lens including: a lens position detection unit configured to detect a position of a lens; a motor configured to move a movable lens frame to which the lens is fixed; a driving state detection unit configured to detect a driving state of the motor; and a control unit configured to decide a driving speed of the motor based on a difference between a target speed, which is based on a difference between a target position of the lens acquired from an imaging device and the position of the lens detected by the lens position detection unit, and a speed according to the driving state detected by the driving state detection unit.

Abstract: A lens apparatus that includes an optical system including a positive lens, the lens apparatus including a holding member arranged to hold the positive lens, an exterior member arranged to accommodate the holding member, and an engaging mechanism arranged to engage the holding member and the exterior member to each other.

Abstract: Provided is a zoom lens consisting of: a positive first lens unit; a negative second lens unit; a positive third lens unit; and a rear lens group including at least one lens unit, wherein an interval between each pair of adjacent lens units is changed during zooming. The rear lens group includes a negative lens unit LR including at least one positive lens and at least one negative lens. The at least one negative lens includes a negative lens made of a material having a largest Abbe number of the at least one negative lens. Each of an extraordinary partial dispersion ratio of the material, distances of a lens surface on an image side of the lens unit LR to an image plane at a telephoto end and at a wide angle end, and a focal length of the lens unit LR is appropriately set.

Abstract: A variable magnification optical system includes, sequentially from an object side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, a third lens unit having a positive refractive power, a fourth lens unit, and a fifth lens unit having a positive refractive power, and each of the lens units makes a different movement relatively to a lens unit that is adjacently positioned at least at one of a time of changing magnification, a time of focusing, and a time of image stabilization.

Abstract: A zoom lens includes a first lens group, a second lens group, a third lens group, a fourth lens group and an aperture. The first lens group, the second lens group, the third lens group and the fourth lens group are sequentially arranged in a direction. The aperture is located between the second lens group and the third lens group. When the zoom lens performs a zoom operation, the first lens group and the third lens group are fixed and the second lens group and the fourth lens group are moved, and a moving distance of the fourth lens group on an optical axis of the zoom lens is less than 5 mm.

Abstract: A zoom optical system and automated luminaire are provided. The zoom optical system includes a light source, a compensator lens group, a variator lens group, and an objective lens group. The light source illuminates an object located in an object plane. The compensator lens group is optically coupled to the object, has a first positive optical power, and moves relative to the object plane. The variator lens group is optically coupled to the compensator lens group, has a negative optical power, and moves relative to the object plane and the compensator group. The objective lens group is optically coupled to the variator lens group, has a second positive optical power, remains in a fixed position relative to the object plane, and projects an image of the object.

Abstract: The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for transmitting, by a user equipment (UE), data in a wireless communication system, the method comprising: receiving a physical downlink control channel (PDCCH) scheduling a physical downlink shared channel (PDSCH); triggering transmission of a scheduling request (SR); and if a transmission time interval (TTI) for an SR transmission is part of reception of the PDSCH, instructing a physical layer to transmit the SR after the PDSCH reception is completed.

Abstract: The imaging lens includes, in order from the object side, a first lens group that remains stationary during focusing; a diaphragm; and a positive second lens group that moves to the object side during focusing from a long range to a close range. The first lens group includes, in order from the object side: a negative meniscus lens that has an absolute value of a radius of curvature of an image side surface smaller than that of an object side surface, a negative lens, a positive lens, and a negative lens. The second lens group includes five or less lenses, and includes: a positive Z lens that is formed continuously in order from a most image side; a negative Y lens that has an absolute value of a radius of curvature of an object side surface smaller than that of an image side surface; and a positive X lens.

Abstract: There is provided a lens system includes a first optical system and forms an intermediate image, which has been formed inside the first optical system by light from an input side, into a final image. The first optical system includes a first subsystem, with the first subsystem including a first lens that is disposed at a position closest to the intermediate image on the input side and moves during focusing and a second lens that is disposed at a position closest to the intermediate image on the output side and moves during focusing.

Abstract: A variable power optical system (ZL) used for an optical apparatus, such as a camera (1), includes, in order from an object: a first lens group (G1) having positive refractive power; a second lens group (G2) having negative refractive power; a third lens group (G3) having positive refractive power; and a fourth lens group (G4) having positive refractive power. The distance between the respective lens groups changes upon zooming from the wide-angle end state to the telephoto end state. The third lens group (G3) includes: an intermediate group (G3b) constituted by a positive lens, a negative lens, a negative lens, and a positive lens; and an image side group (G3c) having negative refractive power and disposed to an image side of the intermediate group (G3b). Upon focusing, the position of the intermediate group (G3b) with respect to the image plane is fixed and the image side group (G3c) moves along the optical axis.

Abstract: The present disclosure discloses a camera optical lens. The camera optical lens including, in an order from an object side to an image side, a first lens, a second lens having a positive refractive power, a third lens having a positive refractive power, a fourth lens, a fifth lens, and a sixth lens. The first lens is made of plastic material, the second lens is made of plastic material, the third lens is made of plastic material, the fourth lens is made of glass material, the fifth lens is made of plastic material, and the sixth lens is made of glass material. The camera optical lens further satisfies specific conditions.

Abstract: An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens, sequentially disposed from an object side to an imaging plane. The optical imaging system satisfies the expression BFL/f<0.15, where BFL represents a distance from an image-side surface of the eighth lens to an imaging plane of an image sensor and f represents an overall focal length of the optical imaging system.

Abstract: A variable magnification optical system includes: a first lens group having positive refractive power and arranged closest to an object; a negative lens group having negative refractive power; a positive lens group which has positive refractive power, which includes at least one lens that moves integrally with an aperture stop, and which is arranged closer to an image than the negative lens group; and a focusing group arranged between the negative lens group and the positive lens group. When varying magnification, distances between the first lens group and the negative lens group and between the negative lens group and the positive lens group are changed. When focusing, distances between the focusing group and a lens facing an object-side of the focusing group and between the focusing group and a lens facing an image-side of the focusing group are changed. A predetermined conditional expression is satisfied.

Abstract: A dual-aperture zoom camera comprising a Wide camera with a respective Wide lens and a Tele camera with a respective Tele lens, the Wide and Tele cameras mounted directly on a single printed circuit board, wherein the Wide and Tele lenses have respective effective focal lengths EFLW and EFLT and respective total track lengths TTLW and TTLT and wherein TTLW/EFLW>1.1 and TTLT/EFLT<1.0. Optionally, the dual-aperture zoom camera may further comprise an optical OIS controller configured to provide a compensation lens movement according to a user-defined zoom factor (ZF) and a camera tilt (CT) through LMV=CT*EFLZF, where EFLZF is a zoom-factor dependent effective focal length.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and positive third and fourth lens groups, in that order from the object side. Upon zooming from the short to long focal length extremities, the first lens group does not move along the optical axis direction, and the second lens group and the third lens group are movable in the optical axis direction. The first lens group includes at least one negative lens element, and the following conditions are satisfied: ?d1n<22.85 and ?8.0<f3/f2<?3.0, wherein ?d1n designates the Abbe number, with respect to the d-line, of the negative lens element, which is provided closest to the object side within the first lens group, and f2 and f3 designate the focal lengths of the second and third lens groups, respectively.

Abstract: Provided is a zoom lens, including, in order from an object side to an image side: a first lens unit having a positive refractive power that does not move for zooming; a second lens unit having a negative refractive power that moves during zooming; at least one lens unit that moves during zooming; and a rear lens unit including an aperture stop, in which a focal length of the zoom lens at a wide angle end, a focal length of the first lens unit, a focal length of the second lens unit, and a half angle of field of the zoom lens at the wide angle end are appropriately set.

Abstract: A zoom lens includes a positive first unit, a negative second unit, and a rear lens system. The rear lens system includes a positive unit A, a negative unit B, and a positive C. The first unit is not moved for zooming, the unit A is moved for zooming, and intervals between adjacent lens units are changed during zooming. The first unit includes positive and negative lenses, the unit C includes positive and negative lenses, the second unit includes negative lenses, and the unit B includes positive lenses. An Abbe number average value of the positive lenses in the first unit, an Abbe number average value of the negative lenses in the second unit, an Abbe number average value of the positive lenses in the unit B, and an Abbe number average value of the positive lenses in the unit C are appropriately set.

Abstract: A photographing optical lens system includes at least six lens elements, wherein the photographing optical lens system includes at least one cemented lens group cemented by two of the lens elements adjacent to each other. The at least one cemented lens group includes, in order from an object side to an image side, a first cemented lens element, a cemented layer and a second cemented lens element. The first cemented lens element has a cemented image-side surface being aspheric. The cemented layer has a cemented object-side surface and a cemented image-side surface. The second cemented lens element has a cemented object-side surface being aspheric. An aspheric coefficient of the cemented image-side surface of the first cemented lens element is different from an aspheric coefficient of the cemented object-side surface of the second cemented lens element. One of the lens elements closest to an imaged object has positive refractive power.

Abstract: Provided is a zoom lens having, in order from an object, a first lens group (G1) having positive refractive power, a second lens group (G2) having negative refractive power, a third lens group (G3) having positive refractive power, and a fourth lens group (G4) having positive refractive power. Upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group changes, a distance between the second lens group and the third lens group changes, a distance between the third lens group and the fourth lens group changes, and at least the first lens group (G1) moves. The first lens group (G1) is constituted by a set of cemented lenses, the third lens group (G3) is constituted by, in order from the object, a positive lens and a negative lens, and the conditional expression 0.50<TL/ft<1.

Abstract: An ocular lens consists of a positive first lens group, a positive or negative second lens group, and a positive third lens group, in order from an observation object side. The first lens group consists of a positive meniscus lens with a convex surface toward an eye-point side. The second lens group includes a negative lens and a positive lens, and the number of lenses constituting the second lens group is three or less. The third lens group consists of a positive meniscus lens with a convex surface toward the eye-point side. The following conditional expression relating to a focal length of the whole system and a distance on an optical axis from a lens surface closest to the observation object side to a lens surface closest to the eye-point side is satisfied: 0.8<f/TL<1.1.

Abstract: The zoom lens consists of, in order from the object side, a first lens group that has positive refractive power, a second lens group that has a negative refractive power, a third lens group that has a positive refractive power, a stop, and a fourth lens group that has a positive refractive power. During zooming, the second lens group and the third lens group move, and the other lens groups and the stop remain stationary. The second lens group consists of, in order from the object side, a second A lens group that has a cemented lens at a position closest to the image side, consists of three or less lenses, and has a negative refractive power, a second B lens group that consists of one or more negative single lenses, and a second C lens group that consists of a cemented lens and has a negative refractive power.

Abstract: A compact optical system includes, in order from an object side to an image side, a first lens element, a second lens element and a third lens element. The first lens element with negative refractive power has an image-side surface being concave in a paraxial region thereof. The second lens element has refractive power, wherein at least one of two surfaces of the second lens element is aspheric, and the second lens element is made of plastic material. The third lens element has positive refractive power, wherein at least one of two surfaces of the third lens element is aspheric, and the third lens element is made of plastic material. The compact optical system further comprises a stop located between the first lens element and the second lens element. The first, second, and third lens elements are all stationary relative to one another in a paraxial region.