Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: There is provided an image forming optical system in which, it is possible to achieve both, the small-sizing and slimming of an optical system, and a favorable correction of various aberrations, mainly the chromatic aberration. In an image forming optical system including a lens component in which, a shape of another optical surface C of an intermediate layer L2 which is made of a transparent material having Abbe's number ?d2 which is in a close contact with one optical surface B of a lens L1 which is made of a transparent material having Abbe's number ?d1, is an aspheric shape differing from (a shape of) the optical surface B, and furthermore, a lens L3 which is made of a transparent material having Abbe's number ?d3 is in a close contact with the optical surface C, the following conditions are satisfied 0.012<1/?d3?1/?d1<0.090??(1) 0.

Abstract: An optical system includes, in order from its object side a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit. The air gaps between the lens units are variable during zooming. The first lens unit includes one positive lens, the second lens unit includes one negative lens, the third lens unit consists of one or two lens components, and the fourth lens unit consists of one lens component, where the term “lens component” refers to a single lens or a cemented lens. The system satisfies the condition “0<M3/M2<0.55”, where M2 and M3 are the amounts of movement of the second lens unit and the third lens unit respectively during zooming from the wide angle end to the telephoto end in the state in which the zoom lens is focused on an object point at infinity.

Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement, of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: It is preferable that for an image forming optical system a basic structure which includes a first lens group having a negative refracting power, which is made of one cemented lens component, a second lens group having a positive refracting power, a third lens group having a positive refracting power, which is made of one lens component, and is movable for focusing, and a fourth lens group which is made of one lens component having an aspheric surface, and at the time of zooming from a wide angle end to a telephoto end, the second lens group moves only toward the object side, and the first lens group and the third lens group move while following a trajectory of movement different from a trajectory of movement of the second lens group is adopted, and that the image forming optical system satisfies predetermined conditional expressions.

Abstract: In an image forming optical system which includes in order from an object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, an aperture stop, a third lens group G3 having a positive refractive power, and a fourth lens group G4 having a negative refractive power, and in which, at the time of zooming, air distances between lens groups are variable, and an air lens nearest to an image side in the third lens group G3 has a shape of a convex lens, the fourth lens group G4 includes one lens component, and is movable even at the time of focusing, and satisfies the following conditional expressions 0.5<(R4F+R4R)/(R4F?R4R)<8.0 ??(1) ?12.0<(R4LAF+R4LAR)/(R4LAF?R4LAR)<?2.

Abstract: In an image forming optical system which includes in order from an object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, and a fourth lens group G4, and which includes maximum of five lens groups, and at the time of zooming from a wide angle end to a telephoto end, when a focal length of the overall image forming optical system is in a range of 1.2 fw to 1.8 fw, the first lens group G1 moves to be positioned more toward the object side than a position at the wide angle end, in a rectangular coordinate system in which, a horizontal axis is let to be ?d(LA) and a vertical axis is let to be nd(LA), when a straight line expressed by nd(LA)=a×?d(LA)+b(LA)(provided that a=?0.0267) is set, the image forming optical system satisfies a predetermined conditional expression.

Abstract: An image forming optical system has a positive lens group disposed closer to its object side than an aperture stop, and the values of ?gF1 and other constants of at least one lens LA included in the positive lens group fall within three ranges including a range bounded by the straight lines given by the equation ?gF1=?1×?d1+?gF1 (where ?1=?0.00566) into which the lowest and highest values in the range given by a first conditional expression are substituted respectively, a range bounded by the straight lines given by the equation nd1=a1×?d1+b1 (where a1=?0.0267) into which the lowest and highest values in the range given by a second conditional expression are substituted respectively, and a range defined by a third conditional expression.

Abstract: An image forming optical system comprising, in order from the object side: a first lens group G1 that is fixed during zooming and includes a reflecting optical element for bending an optical path; a second lens group G2 having a negative refracting power and movable during zooming; a third lens group G3 having a positive refracting power; a fourth lens group G4 having a positive refracting power; and a rearmost lens group GR, wherein during zooming from the wide angle end to the telephoto end, the third lens group G3 moves on the optical axis toward the object side, characterized in that the rearmost lens group GR satisfies the following condition: 0.95<?Rw<2.5 . . . (1-1).

Abstract: There is provided an image forming optical system in which, it is possible to achieve both, the small-sizing and slimming of an optical system, and a favorable correction of various aberrations, mainly the chromatic aberration. In an image forming optical system including a lens component in which, a shape of another optical surface C of an intermediate layer L2 which is made of a transparent material having Abbe's number ?d2 which is in a close contact with one optical surface B of a lens L1 which is made of a transparent material having Abbe's number ?d1, is an aspheric shape differing from (a shape of) the optical surface B, and furthermore, a lens L3 which is made of a transparent material having Abbe's number ?d3 is in a close contact with the optical surface C, the following conditions are satisfied 0.012<1/?d3?1/?d1<0.090??(1) 0.

Abstract: To provide an image forming optical system that can achieve good correction of chromatic aberration, which is seriously needed particularly when the zoom ratio is high, while achieving slimness and a high zoom ratio and to provide an electronic image pickup apparatus equipped with such an image forming optical system, an image forming optical system has a lens group A including a lens component made up of a positive lens LA and a negative lens LB cemented together and having a negative refracting power as a whole. The lens group A is arranged between a lens group I closest to the object side and an aperture stop. The distance between the lens group I and the lens group A changes for zooming. The lens component has an aspheric cemented surface, and a certain condition concerning the shape of the aspheric surface is satisfied.

Abstract: A lens component of the present invention is made by cementing a lens LA and a lens LB having a refracting power smaller than a refracting power of the lens LA, and satisfies predetermined conditional expressions. Moreover, in an image forming optical system of the present invention which includes a lens group B having a negative refracting power, a lens group C having a positive refracting power and which moves only toward an object side at the time of zooming from a wide angle end to a telephoto end, and one or two more lens groups additionally, one of the lens components of the present invention is used in the lens group B.

Abstract: A zoom optical system having a lens group I including two single lenses or one lens component, an aperture stop, and a lens group A disposed between the lens group I and the aperture stop, including a lens component made up of a positive lens LA and a negative lens LB that are cemented together, and having a negative refracting power as a whole. The distance between the lens group I and the lens group A on the optical axis changes for zooming, and the lens component has an aspheric cemented surface. When the shape of the aspheric surface is expressed by a certain equation, the shape of the air-contact surface of the positive lens LA and its aspheric components etc. satisfy conditional expressions (3a) and (3b).

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: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement, of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom 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 image forming optical system comprising, in order from the object side: a first lens group G1 that is fixed during zooming and includes a reflecting optical element for bending an optical path; a second lens group G2 having a negative refracting power and movable during zooming; a third lens group G3 having a positive refracting power; a fourth lens group G4 having a positive refracting power; and a rearmost lens group GR, wherein during zooming from the wide angle end to the telephoto end, the third lens group G3 moves on the optical axis toward the object side, characterized in that the rearmost lens group GR satisfies the following condition: 0.95<?Rw<2.5??(1-1).

Abstract: The invention relates to an electronic image pickup system whose depth dimension is extremely reduced, taking advantage of an optical system type that can overcome conditions imposed on the movement of a zooming movable lens group while high specifications and performance are kept. The electronic image pickup system comprises an optical path-bending zoom optical system comprising, in order from its object side, a 1-1st lens group G1-1 comprising a negative lens group and a reflecting optical element P for bending an optical path, a 1-2nd lens group G1-2 comprising one positive lens and a second lens group G2 having positive refracting power. For zooming from the wide-angle end to the telephoto end, the second lens group G2 moves only toward the object side. The electronic image pickup system also comprises an electronic image pickup device I located on the image side of the zoom optical system.

Abstract: A zoom lens with an easily bendable optical path has high optical specification performance such as a high zoom ratio, a wide-angle arrangement, a small F-number and reduced aberrations. It includes a first lens group G1 remaining fixed during zooming, a second lens group G2 having negative refracting power and moving during zooming, a third lens group G3 having positive refracting power and moving during zooming, and a fourth lens group G4 having positive refracting power and moving during zooming and focusing. The first lens group comprises, in order from an object side thereof, a negative meniscus lens component convex on an object side thereof, a reflecting optical element for bending an optical path and a positive lens. Upon focusing on an infinite object point, the fourth lens group G4 moves in a locus opposite to that of movement of the third lens group G3 during zooming.

Abstract: In an image forming optical system having a positive lens group, a negative lens group, and an aperture stop, the positive lens group being disposed at an image-plane side of the aperture stop and having a cemented lens, and 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 an area which is determined by a line when a lower limit value is in a range of a following conditional expression (1), and a line when an upper limit value is in a range of the following conditional expression (1), and in an area determined by following conditional expressions (2) and (3) 1.45<?<2.15??(1) 1.30<Nd<2.20??(2) 3<?d<25??(3) Here, Nd denotes a refractive index, and ?d denotes an Abbe's number.