Abstract: An image pickup apparatus includes an image forming optical system having an aperture stop, a first lens, and a second lens, and an imager having a light-receiving surface that is curved to be concave toward the image forming optical system, and a relative partial dispersion for a medium of the first lens differs from a relative partial dispersion for a medium of the second lens, and when a straight line indicated by ?gFLA=?×?dLA+?LA (where ?=?0.00163) has been set, ?gFLA and ?dLA for the medium of the first lens are included in both of an area determined by the following conditional expression (1) and an area determined by the following conditional expression (2), and the following conditional expression (3) is satisfied: 0.68<?LA ??(1), ?dLA<50 ??(2), and 0<|f/Rimg|?1.5 ??(3).

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: 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-banding 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 includes, a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit, and the first lens unit either includes a negative lens and a positive lens, or includes a negative lens, a negative lens, and a positive lens, and the second lens unit includes a first lens component and a second lens component, and the second lens component includes a cemented lens, and the third lens unit includes either one lens or two lenses as a whole, and a lens having a curvature of a surface on an image side larger than a curvature of a surface on the object is disposed nearest to an object, and the fourth lens unit includes one positive lens component.

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-banding 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: 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 includes, a negative first lens unit, a positive second lens unit, a negative third lens unit, and a positive fourth lens unit, and the first lens unit either includes a negative lens and a positive lens, or includes a negative lens, a negative lens, and a positive lens, and the second lens unit includes a first lens component and a second lens component, and the second lens component includes a cemented lens, and the third lens unit includes either one lens or two lenses as a whole, and a lens having a curvature of a surface on an image side larger than a curvature of a surface on the object is disposed nearest to an object, and the fourth lens unit includes one positive lens component.

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 includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a positive refractive power, and a last lens group having a positive refractive power. At the time of zooming from a wide angle end to a telephoto end, the second lens group and the third lens group move, and one of the fourth lens group, the fifth lens group, and the last lens group moves.

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 includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive, and a last lens group having a positive refractive index, and at the time of zooming from the wide angle end to the telephoto end, the first lens group is fixed, the second lens group moves toward a side of an image plane, the third lens group is fixed, and the fourth lens group moves, and at the time of focusing, the fourth lens group moves. The zoom lens satisfies the following conditional expression (101) 0.20<log(?34T/?34W)<0.9·log ???(101).

Abstract: A zoom lens includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a negative refractive power, a fourth lens group having a positive refractive power, a fifth lens group having a positive refractive power, and a last lens group having a positive refractive power. At the time of zooming from a wide angle end to a telephoto end, the second lens group and the third lens group move, and one of the fourth lens group, the fifth lens group, and the last lens group moves.

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: 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 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: 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)<?2.0??(2).

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 zoom lens includes in order from an object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, a fourth lens group having a positive refractive, and a last lens group having a positive refractive index, and at the time of zooming from the wide angle end to the telephoto end, the first lens group is fixed, the second lens group moves toward a side of an image plane, the third lens group is fixed, and the fourth lens group moves, and at the time of focusing, the fourth lens group moves. The zoom lens satisfies the following conditional expression (101) 0.20<log(?34T/?34W)<0.

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: An electronic imaging apparatus has a zoom optical system in which the most object-side lens unit A includes one biconcave-shaped negative lens component, each of air-contact-surfaces of which is configured as an aspherical surface, and when the magnification of the zoom optical system is changed in the range from a wide-angle position to a telephoto position, the lens unit A is moved back and forth along the optical axis in such a way that the lens unit A is initially moved toward the image side, and an electronic imaging unit that has an electronic image sensor so that image data picked up by the electronic image sensor are electrically processed and can be output as image data whose format is changed. In this case, in nearly infinite object point focusing, the zoom optical system satisfies the following condition: 0.7<y07/(fw·tan ?07w)<0.94 where y07 is expressed by y07=0.