Abstract: A varifocal liquid lens includes a body filled with two different fluids separated by an interface of a variable curvature across a clear aperture of the varifocal liquid lens. At least one of the first or second fluids is birefringent, such that a refractive index difference between the first and second fluids and resulting optical power of the varifocal liquid lens is dependent on polarization of impinging light. At a first light polarization, the first and second fluids may be matched in refractive index, while at a second, orthogonal light polarization, the first and second fluids may be mismatched in refractive index, whereby the first interface between the first and second fluids may have a variable, non-zero optical power for the second polarization while having a substantially non-variable, zero optical power for the first polarization of light.

Abstract: An imaging lens system includes an optical path folding member including a forwardmost reflective surface disposed closest to an object side, a rearmost reflective surface disposed closest to an imaging plane, and a rear reflective surface disposed to form an acute angle with the rearmost reflective surface and configured to reflect light reflected by the rearmost reflective surface to the imaging plane, and a first lens group disposed on an object side of the forwardmost reflective surface or an image side of the forwardmost reflective surface, wherein an angle between a first virtual plane including the forwardmost reflective surface and a second virtual plane including the rearmost reflective surface is 15 to 27 degrees.

Abstract: A 4K high-resolution panoramic annular optical system includes a panoramic annular lens head unit, a subsequent lens group, and a 4K sensor (SE) that is coaxially installed. The panoramic annular lens head unit includes a first lens (PALIPAL1) and a second lens (PAL2). The subsequent lens group includes a third lens (RL1), a fourth lens (RL2), a fifth lens (RL3), a sixth lens (RL4), a seventh lens (RL5), an eighth lens (RL6), and a ninth lens (RL7) that are arranged in order from an object plane to an image plane. The first lens (PAL1) and the fifth lens (RL3) are meniscus glass lenses with positive refractive power. The six lens (RL4) and the ninth lens (RL7) are meniscus glass lenses with negative refractive power, and the second lens (PAL2), the fourth lens (RL2), the seventh lens (RL5), and the eighth lens (RL6) are biconvex lenses with positive refractive power.

Abstract: A hypersonic self-guided missile system is described. Particularly, embodiments describe missiles whose trajectories are controlled by an on-board control unit that decrease the effect of damaging heat to sensitive internal components by employing one or more annular windows, internal mirrors, lenses, and/or cameras. Embodiments may have an internal camera oriented substantially toward or away from the nose of the missile.

Abstract: A fixed-focus projection lens has a first lens group and a second lens group in sequence along an optical axis from a screen side to a light modulator side. The first lens group has a positive refractive power, and the second lens group has a positive refractive power. The first lens group has two lenses, and the refractive powers of the lenses are negative and positive. The second lens group has five lenses, and the refractive powers of the lenses respectively are negative, negative, positive, positive, and positive. The fixed-focus projection lens has the features of small size and high optical performance.

Abstract: Disclosed is a lens system for removable connection to a portable programmable device which includes a camera. This lens system can be arranged in various embodiments to modify the field of view experienced by this camera, and in specific embodiments can modify the direction of this cameras field of view. The device can also be used to provide software capable of executing on a portable programmable device, in addition to providing a light pipe to redirects light used as a photographic flash in applications where it modifies the direction of view of a camera.

Abstract: An optical scanner, scanner apparatus, or scanner assembly, which may be particularly advantageous for use in a multiphoton microscope, includes a first drivable bending component, a second drivable bending component mounted perpendicularly to the first component, and at least one optical waveguide coupled one or both of the first and second bending components, wherein the at least one optical waveguide provides both a propagation path for a multiphoton excitation radiation delivery between a light source and a target and a multiphoton-induced emission radiation delivery between the target and a detector. A GRIN relay lens. A multiphoton microscope incorporating the scanner and the GRIN relay lens.

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

Abstract: According to one embodiment, the imaging device array in an embodiment has plural imaging devices formed integrally, imaging the light that is output from the exit surface imaged at the image point including an incidence surface for the incidence of light, plural reflective surfaces including four reflective surfaces for reflecting the light from the incidence surface, and an exit surface that outputs light that has gone through the plural reflective surfaces, in which the plural imaging devices are arranged as an array, and a surface for ameliorating the propagation of light other than the light reflected from the reflective surfaces to the exit surface is formed on the periphery of at least one reflective surface among the plural reflective surfaces.

Abstract: Embodiments of the invention include an optical system and an optical system module, coupled to a distal end of a fluorescence emission endoscope apparatus, an optical waveguide-based fluorescence emission endoscopy system, and a method for remotely-controlled, multi-magnification imaging of a target or fluorescence emission collection from a target with a fluorescence emission endoscope apparatus. An exemplary system includes an objective lens disposed in a distal end of an endoscope apparatus. The lens is adapted to transmit both a visible target illumination and a fluorescence-emission-inducing target illumination as well as fluorescence-emission and visible light from the target. The system can thus simultaneously provide low magnification, large field of view imaging and high magnification, high-resolution multiphoton imaging with a single lens system.

Abstract: An optical element of the present invention is provide with a first surface which is formed on the front-object side and upon which light from the front-object side is incident, a second surface formed on the image side, and a third surface which is formed between the first surface and the second surface and upon which light from the generally lateral object side is incident. The first surface is provided with a first transmission surface formed around the optical axis and a first reflection surface which faces the image side and which is formed annularly around the first transmission surface. The second surface is provided with a second transmission surface formed around the optical axis, and a second reflection surface which faces the front object side and which is formed annularly around the second transmission surface.

Abstract: An observation optical system has a negative lens unit placed at the most object-side position; an annular prism placed on the image side of the negative lens, having a reflecting surface on the negative lens side; and an imaging lens unit arranged on the image side of the negative lens and the annular prism.

Abstract: A lens module includes an elongated lens having a first lens, first reflect face formed on a front end thereof. A second lens and a second reflect face are respectively formed on a rear end of the elongated lens. When collecting an image, the light route of the object passes through the first lens and the first reflect face into the elongated lens, and focusing a wrong-reading image. The light route of the wrong-reading image passes through the second reflect face and the second lens and forms a light route that forms a right-reading image on a sensitize unit.

Abstract: Provided is a condensing lens condensing a light from a light source, and a lighting device equipped with the condensing lens. The condensing lens may enable a light to be selectively incident upon a plurality of first incident portions based on an emission angle, may totally-reflect, using a second incident portion, the light refracted by the plurality of first incident portions, and may refract the totally-reflected light using a third incident portion.

Abstract: An LED unit includes a printed circuit board, an LED mounted on the printed circuit board, and a lens covering the LED and fixed on the printed circuit board. The lens includes a pedestal and an optical element connected to the pedestal. The lens has a light-incident face formed in an interior thereof for receiving light emitted from the LED into the lens, and a light-emergent face formed on an outside thereof for refracting the light out of the lens. The optical element has two opposite sides longer than the other two opposite sides thereof so that the light pattern modulated by the optical element has two opposite ends wider than a middle thereof.

Abstract: An optical system for observing front and lateral objects includes a negative front group having a reflective refractive element, an aperture stop, and a positive rear group having a moving lens unit that is movable along the optical axis. The reflective refractive element includes a front-object-side first face having a transmitting surface and a reflective surface annularly formed around the transmitting surface, an image-side second face having a transmitting surface and a reflective surface annularly formed around the transmitting surface, and a face formed as a transmitting surface between the first and second faces. The optical system performs focusing onto an object while hardly changing, in the entire observation area, an area in which an image of the front object is formed, by moving the moving lens unit to the extent that the refractive powers of the front and rear groups hardly change relative to each other.

Abstract: An optical system includes a negative front group having a component of first and second lenses cemented together, an aperture stop, and a positive rear group. The component has: a first face, on the front-direction-object side of the first lens, having a first transmitting surface and an annularly-formed first reflecting surface facing the image side; a second face, at the cemented surface, having a second transmitting surface and an annularly-formed second reflecting surface facing the front-direction-object side; a third face as a transmitting surface on the image side of the second lens; and a fourth face as a transmitting circumferential face of the first lens. The component satisfies the conditions: |nd—RL1?nd—RL2|<0.3 |vd—RL1?vd—RL2|<40 where nd—RL1 and nd—RL2 are refractive indices for d line, of the first and second lenses, respectively, and vd—RL1 and vd—RL2 are Abbe's numbers for d line, of the first and second lenses, respectively.

Abstract: An imaging device includes a light source; a prism having an imaging surface to be contacted with an object; and an image-forming optical system that forms an image of the object. The image-forming optical system includes a front lens group having a first optical axis tilted relative to the imaging surface; an image plane tilted from a surface perpendicular to the first optical axis of the front lens group; and a rear lens group having a second optical axis shifted in parallel to the first optical axis of the front lens group. The image-forming optical system is arranged to satisfy the following conditional expression: |Aim|/(90°?Ain)<0.5 Where Ain is an acute angle between the imaging surface and the first optical axis, and Aim is an angle between the image plane and a surface perpendicular to the first optical axis.

Abstract: A unit magnification projection optical system includes, listed in order along a system axis, a mirror, a lens group having negative power and a lens group having positive power. The optical system is a symmetric system, with an object plane on one side of the system axis and an object plane on an opposite side of the system axis. The object and image planes are spaced apart from the positive lens group by a working distance greater than 100 millimeters.

Abstract: A lens barrel includes a fourth lens, a prism, and a sixth lens. The fourth lens receives a light flux incident along a first optical axis. The prism includes a reflecting surface reflecting the light flux passing through the fourth lens to a direction along a second optical axis intersecting with the first optical axis. The sixth lens receives the light flux reflected by the prism. A second group frame includes an opening portion, a prism retaining frame that is arranged in a more inner position than the opening portion and in which the prism is contained, and a plurality of adhesive pockets arranged on an area around the prism retaining frame and being open to the side of the opening portion. Adhesive agent is filled in the adhesive pockets.

Abstract: An optical system includes, in order from a front-direction-object side, a first group with a negative refracting power having a reflecting/refracting optical element, an aperture stop, and a rear group with a positive refracting power.

Abstract: An image forming optical system according to the present invention is characterized in that, in an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group is disposed at an object side of the aperture stop, the positive lens group has a cemented lens which is formed by cementing a plurality of lenses, in a rectangular coordinate system in which a horizontal axis is let to be Nd and a vertical axis is let to be ?d, when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens is included in both of areas namely, an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1a), and a line when an upper limit value is in a range of the following conditional expression (1a), and of an area determined by following conditional expressions (2a) and (3a). 1.45<?<2.15??(1a) 1.30<Nd<2.

Abstract: A flux of light entering a transparent medium proceeds along a side view optical path by way of a first transmissive surface so as to be reflected to the side opposite to an image plane by a first reflective surface and then to the image plane side by a second reflective surface to form an optical path before going out from the transparent medium to the outside at the image plane side by way of a second transmissive surface in the order of forward ray tracing and also along a direct view optical path by way of a third transmissive surface to form another optical path before going out from the transparent medium into the outside at the image plane side by way of a fourth transmissive surface also as viewed in the order of forward ray tracing.

Abstract: In an optical system for observing a front object and an approximately lateral object, a front group having a reflective refractive optical element and negative refractive power, an aperture stop, and a rear group having a moving lens group and positive refractive power are arranged in order from the front-object side, where the moving lens group moves in the direction along the optical axis, the reflective refractive optical element includes a first surface which has a first transmitting surface and a first reflective surface and is formed on the front-object side, where the first transmitting surface is formed with the center of the first transmitting surface on the optical axis and the first reflective surface is formed in the shape of a ring and around the first transmitting surface and faces toward the image side, a second surface which has a second transmitting surface and a second reflective surface and is formed on the image side, where the second transmitting surface is formed with the center of the

Abstract: An optical module for increasing magnification of a microscope includes an objective and an eyepiece between which is an optical path for light to travel. The optical includes light diverging elements for dividing the optical path into two parallel light paths after leaving the objective; and several orthonormally-arranged reflective elements including at least a first and a last reflective element, each reflective element having a reflective surface diagonal relative to the orthonormal arrangement of the elements, and also arranged to successively reflect the parallel light paths, from element to element, from the objective when the module is inserted in the optical microscope, beneath the eyepiece. Also included are light converging elements for converging the parallel paths into a single path before producing an image at the eyepiece.

Abstract: A fixed-focus lens capable of imaging a light valve disposed at a reduced side onto a magnified side is provided. The fixed-focus lens includes a first lens group, a second lens group, and a free form reflective mirror. The first lens group is disposed in the light path between the reduced side and the magnified side. The second lens group is disposed in the light path between the first lens group and the magnified side and includes a first free form lens. The free form reflective mirror is disposed in the light path between the second lens group and the magnified side. An imaging surface imaged from the light valve by the fixed-focus lens is a curved surface. An imaging system using the fixed-focus lens is also provided.

Abstract: A fingerprint navigation system with a folded air lens structure and a folded air lens. The system includes a light source, a folded air lens structure, a light reflector, and a navigation sensor. The folded air lens structure is aligned to direct light from the light source to an object surface. The folded air lens structure includes a first portion and a second portion. The light reflector is aligned to direct the light from the first portion of the folded air lens structure to the second portion of the folded air lens structure. The navigation sensor is calibrated to produce a navigation image corresponding to the light directed through the folded air lens structure and the folded air lens.

Abstract: A composite optical device 1 includes a first optical section 10 having an optical functional surface 11 and a second optical section 20 bonded to the first optical section 10 on the optical functional surface 11. The optical functional surface 11 includes a smooth part 13 and a concave-convex part 12 adjacent to each other, and is constructed so that a position P2, along a normal direction of the smooth part 13, of a concave bottom of the concave-convex part 12 can be closer to the center of the first optical section 10 than a position P1 along the normal direction of an end of the smooth part 13 on a side of the concave-convex part 12 in a boundary vicinity portion NR between the smooth part 13 and the concave-convex part 12.

Abstract: An observation optical system has a negative lens unit including a cemented lens, arranged at the most object-side position; an annular reflecting mirror placed on the image side of the negative lens unit, with a reflecting surface facing the image side; and an imaging lens unit arranged on the image side of the negative lens unit and the annular reflecting mirror.

Abstract: A flux of light entering a transparent medium L2 proceeds along a side view optical path A by way of the first transmissive surface 21 so as to be reflected to the side opposite to the image plane by the first reflective surface 22 and then to the image plane side by the second reflective surface 23 to form an optical path before going out from the transparent medium L2 to the outside at the image plane 5 side by way of the second transmissive surface 24 in the order of forward ray tracing and also along a direct view optical path B by way of third transmissive surface 25 to form another optical path before going out from the transparent medium L2 into the outside at the image plane 5 side by way of the fourth transmissive surface 26 also as viewed in the order of forward ray tracing.

Abstract: An optical imaging system which produces large field of view with a folded image.

Abstract: There is provided a lens assembly including: a first lens part including a first lens surface as an object-side surface, a second lens surface as an image-side surface, and a peripheral part defining a periphery of the second lens surface; a second lens part disposed at an image side of the first lens part and including at least one lens; a spacer spacing the first lens part and the second lens part from each other; and a light adjustor disposed between the second lens surface and the peripheral part, the light adjustor totally reflecting or refracting light incident at a predetermined angle of view or more.

Abstract: An image pickup apparatus enabling construction of a small bending optical system with high magnification. A first lens group is movably disposed toward an object on a first optical axis. A second lens group is movably disposed radially inward of the first lens group. The second lens group comprises a drive frame drivingly controlled along the first optical axis and a lens holding frame for holding the second lens group. A prism is disposed on the first optical axis, for bending light incident on the prism to thereby guide the light along a second optical axis. The prism is retracted along the second optical axis in a non-shooting state. In the non-shooting state, the second lens group is retracted and accommodated in a space defined by the drive frame and the lens holding frame and a space occupied by the prism in a shooting state.

Abstract: Disclosed is a solar multistage concentrator in which at least one imaging lens system (1) is mounted in front of a non-imaging lens system (3, 4) in such a way that both systems are an integral part of a specifically formed, light-transparent dielectric (2).

Abstract: An image forming optical system according to the present invention is characterized in that, in an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the negative lens group is disposed at an object side of the aperture stop, the negative lens group has a cemented lens which is formed by cementing a plurality of lenses, and in a rectangular coordinate system in which, a horizontal axis is let to be Nd and a vertical axis is let to be ?d, when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens are included in both of areas namely, an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1a), and a line when an upper limit value is in a range of the following conditional expression (1a), and an area determined by following conditional expressions (2a) and (3a). 1.45<?<2.15??(1a) 1.30<Nd<2.

Abstract: A dual focal length optical system includes a first optical system and a second optical system. The first optical system is positioned along an optical path and includes an optical structure having an object side surface and an image side surface. The first optical system also includes a first surface of an intermediate reflective element located between the object side surface and the image side surface of the optical structure as viewed along the optical path. The first optical system has a first focal length. The second optical system shares a portion of the same optical path and includes a second surface of the same intermediate reflective element as that of the first optical system. The second optical system has a second focal length. The first focal length of the first optical system is longer than the second focal length of the second optical system.

Abstract: An image forming optical system according to the present invention is characterized in that, in an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group is disposed at an object side of the aperture stop, the positive lens group has a cemented lens which is formed by cementing a plurality of lenses, in a rectangular coordinate system in which a horizontal axis is let to be Nd and a vertical axis is let to be ?d, when a straight line indicated by Nd=?×?d+? (where, ?=?0.017) is set, Nd and ?d of at least one lens forming the cemented lens is included in both of areas namely, an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1a), and a line when an upper limit value is in a range of the following conditional expression (1a), and of an area determined by following conditional expressions (2a) and (3a). 1.45<?<2.15??(1a) 1.30<Nd<2.

Abstract: An optical apparatus having an off-axis direction of view is disclosed. The optical apparatus advantageously has an outer dimension of less than about 2 mm. The optical apparatus can be utilized as a subsystem of an endoscopic device.

Abstract: A lens barrel has a first lens group, a second lens group, a third lens group, a first support frame for supporting the first lens group, a second support frame for supporting the second lens group, a third support frame for supporting the third lens group, a first drive unit, and a second drive unit. The first lens group has an overall negative refractive power, and includes a prism. The second support frame is driven along a second optical axis by the first drive unit. The third support frame is driven along the second optical axis by the second drive unit. Part of a first movement region in which the second support frame moves overlaps a second movement region in which the third support frame moves.

Abstract: The present invention aims to provide an imaging device and a camera realizing simultaneously a high magnification zoom lens system and the miniaturization of the device. The imaging device (2) includes a first lens group (G1), a second group frame unit (42), a first group frame unit (41), a motor unit (32), a third lens group (G3), and a CCD unit (33). The first lens group (G1) takes in a light flux incident along a first optical axis (A1). The second group frame unit (42) bends the light flux incident along the first optical axis (A1) to a direction along a second optical axis (A2). The first group frame unit (41) retains the first lens group (G1), and moves the first lens group (G1) in the direction along the first optical axis (A1). The motor unit (32) drives the first group frame unit (41).

Abstract: An optical lens assembly comprises two plastic lenses with refractive power: from the object side to the image side: a first lens with positive refractive power, and a second lens with negative refractive power. A front surface and a rear surface of the first lens is convex and aspherical, a refractive index N1 of the first lens satisfies the relation: 1.6>N1>1.5, a focal length of the first lens is f1, and a focal length of optical system is f, and they satisfy the relation: f/f1>2.0. A front surface of the second lens is concave, a rear surface of the second lens is convex, and both the front and rear surfaces is aspherical, a refractive index N2 of the second lens satisfies the relation: N2>1.55. An aperture is located in front of the first lens for controlling the brightness of the optical system.

Abstract: A frame 18 with a first lens group 15 and a second lens group 17 of a projection lens system fixedly mounted thereto is supported by a support arm 43 so as to direct a mirror mounting aperture 27 of the frame 18 downward. The reflection mirror 16 for folding an optical axis of the projection lens system is held and placed within the mirror mounting aperture 27 of the frame 18 by a mirror support 46 so as thereby to provisionally complete the projection lens system. Then, while an image of a test pattern generated by a test pattern projection head 44 is projected onto a remote screen 47 by the provisionally complete the projection lens system, the reflection mirror 16 is adjusted in position by 45 by a mirror position adjusting unit 45.

Abstract: An observation optical system has a negative lens unit including a cemented lens, arranged at the most object-side position; an annular reflecting mirror placed on the image side of the negative lens unit, with a reflecting surface facing the image side; and an imaging lens unit arranged on the image side of the negative lens unit and the annular reflecting mirror.

Abstract: The present invention is directed to a zoom lens used for image pick-up optical system of digital still camera, or video camera, and is composed, in order from the object side, of a first group GR1 including a reflection member for bending or folding the optical axis and having negative refractive power, a second group GR2 having negative refractive power, a third group GR3 having positive refractive power, and a fourth group GR4 having positive refractive power, wherein a light quantity adjustment member ST1 for adjusting light quantity is fixed during zooming operation.

Abstract: There is provided an optical projection system which includes a display device, a first optical system that has a positive power in total and has a first lens group and a second lens group, a second optical system having a reflective surface having a negative power, and a first deflecting system that directs a light beam emerging from the first optical system to the second optical system. The first lens group and the second lens group have a positive power and a negative power, respectively. The first deflecting system is located over the first optical system in a cross sectional plane. The first deflecting system deflects the light beam in a direction moving away from the screen to direct the light beam to the second optical system. The optical projection system satisfies conditions: 6.0>D/f1>2.6 ?1>EXP1/f1>?2.

Abstract: A projection lens system of the present invention projects projection light from a light modulator onto a screen and includes a first lens group disposed closest to the screen, the first lens group including a first meniscus lens with negative refractive power that is positioned closest to the screen and is convex on a screen side, a cemented lens that is positioned on a light modulator side, and a means for bending an optical path between the first meniscus lens and the cemented lens. The means for bending the optical path is disposed between the negative meniscus lens and the cemented lens of the first lens group. Since the cemented lens of the first lens group is disposed in line with the lenses in the second lens group, the lens system of this invention is produced with a slim overall construction even if the cemented lens is in the first lens group.

Abstract: An objective lens system consisting of a first lens unit having a negative refractive power and a second lens unit having a positive refractive power wherein the first lens unit or the second lens unit comprises at least one radial type gradient index lens element which has a refractive index distribution in a radial direction from an optical axis. This objective lens system favorably corrects chromatic aberration and other aberrations by adequately selecting a value expressing an Abbe's number and a refractive power of medium for the radial type gradient index lens element.

Abstract: A high-performance and low-cost image-forming optical system has a reduced number of constituent optical elements and is made extremely thin, particularly in a direction perpendicular to an image pickup device, by folding an optical path using only three reflecting surfaces. The image-forming optical system has a front unit including a first prism 10, an aperture stop 2, and a rear unit including a second prism 20. The first prism 10 has a first transmitting surface 11, a first reflecting surface 12, and a second transmitting surface 13. The second prism 20 has a first transmitting surface 21, a first reflecting surface 22, a second reflecting surface 23, and a second transmitting surface 24. An optical path incident on the first reflecting surface 22 and an optical path exiting from the second reflecting surface 23 intersect each other.

Abstract: A lens system has the first and second lens components from the object side. The first lens component has a negative optical power. The second lens component has a positive optical power. The lens system fulfills the conditions: 0.0<PRL/Y′<0.5, 0.5<Pf/f<1.0. In the conditions, PRL represents a distance in a direction perpendicular to the optical axis between the optical axis and an incident position where a lower ray of a most off-axial rays enters said second lens component, Y′ represents a largest image height, f represents a focal length of the entire lens system, and Pf represents a focal length of said second lens component.

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).