Abstract: The invention provides a zoom lens, characterized by comprising, a zoom lens, which comprises, in order from an object side thereof: a first lens group of negative refracting power, a second lens group of positive refracting power, a third lens group of negative refracting power, and a fourth lens group of positive refracting power, wherein: upon zooming from a wide-angle end to a telephoto end of the zoom lens, a separation between the respective lens groups changes, upon focusing from a focusing-on-infinity state to a close-range focusing state, the third lens group moves in an optical axis direction, and the conditions (1) and (2) are satisfied at the wide-angle end.

Abstract: A zoom lens comprising, in order from the object side to the image 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 having a negative refractive power, and a fifth lens unit having a positive refractive power, wherein the first lens unit is located closest to the object side, the fifth lens unit is located closest to the image side, during zooming from the wide angle end to the telephoto end, the first lens unit, the second lens unit, the third lens unit, and the fourth lens unit move, the fifth lens unit is stationary, and the distances between the lens units vary, the third lens includes a positive lens, and the zoom lens satisfies the following condition (1): 72<?3p<110??(1).

Abstract: In a zoom lens of a fixed total length, at the time of changing the magnification from the wide-angle end toward the telephoto end, the first lens group is anchored while the second lens group is moved, and the third and fourth lens groups are moved so as to be located at the object side of the telephoto end relative to the wide-angle end, such that: the interval between the second and third lens groups is decreased at the telephoto end relative to the wide-angle end; the interval between the third and fourth lens groups is increased at the telephoto end relative to the wide-angle end; and the interval between the fourth and fifth lens groups is increased at the telephoto end relative to the wide-angle end, and at the time of focusing a near object point from a remote object point, the second lens group is moved.

Abstract: An inner focus lens system includes from the object side, a first lens unit having a positive refractive power, an aperture stop, a second lens unit having a positive refractive power, and a third lens unit. The first lens unit includes a plurality of negative lenses and at least one positive lens, the lens located closest to the object side is a negative lens. The second lens unit includes at least one negative lens and at least one positive lens, and moves toward the object side for focusing from an infinite object distance to a close object distance such that the distance between the second lens unit and the aperture stop decreases and that the distance between the second lens unit and the third lens unit increases. The lens system satisfies the following conditions: 1<f1/f 14 (1), and 0.8<f23/f2<3 (2).

Abstract: The invention provides a zoom lens, characterized by comprising, a zoom lens, which comprises, in order from an object side thereof: a first lens group of negative refracting power, a second lens group of positive refracting power, a third lens group of negative refracting power, and a fourth lens group of positive refracting power, wherein: upon zooming from a wide-angle end to a telephoto end of the zoom lens, a separation between the respective lens groups changes, upon focusing from a focusing-on-infinity state to a close-range focusing state, the third lens group moves in an optical axis direction, and the conditions (1) and (2) are satisfied at the wide-angle end.

Abstract: A teleconverter includes a master lens apparatus-side mount on which a master lens apparatus is mounted, a camera body-side mount on which a camera body is mounted, and a converter lens unit that has a negative refracting power for mounting the master lens apparatus thereon to obtain a lens system having a focal length longer than that of the master lens apparatus, the converter lens unit including a first lens group on the master lens apparatus side and a second lens group on the camera body side with an on longest air separation interposed between them, the first lens group has positive refracting power, and the second lens group has negative refracting power, with satisfaction of the following condition (1): ?1.53<f1/f<?0.66??(1) where f is the focal length of a whole system of the converter lens unit, and f1 is the focal length of the first lens group.

Abstract: The invention provides a zoom lens, characterized by comprising, in order from an object side thereof, a first lens group of positive refracting power, a second lens group of negative refracting power, a third lens group of positive refracting power, and a fourth lens group of negative refracting power, upon zooming from a wide-angle end to a telephoto end of the zoom lens, a separation between the respective lens group changes, a separation between the first lens group and the second lens group becomes narrow, and a separation between the second lens group and the third lens group grows wide; upon focusing from a focusing-on-infinity state to a close-range focusing state, the fourth lens group moves in an optical axis direction; and Conditions (1) and (2) are satisfied at the wide-angle end.

Abstract: In a zoom lens of a fixed total length, at the time of changing the magnification from the wide-angle end toward the telephoto end, the first lens group is anchored while the second lens group is moved, and the third and fourth lens groups are moved so as to be located at the object side of the telephoto end relative to the wide-angle end, such that: the interval between the second and third lens groups is decreased at the telephoto end relative to the wide-angle end; the interval between the third and fourth lens groups is increased at the telephoto end relative to the wide-angle end; and the interval between the fourth and fifth lens groups is increased at the telephoto end relative to the wide-angle end, and at the time of focusing a near object point from a remote object point, the second lens group is moved.

Abstract: The invention provides a zoom lens, characterized by comprising, in order from an object side thereof, a first lens group of positive refracting power, a second lens group of negative refracting power, a third lens group of positive refracting power, and a fourth lens group of negative refracting power, upon zooming from a wide-angle end to a telephoto end of the zoom lens, a separation between the respective lens group changes, a separation between the first lens group and the second lens group becomes narrow, and a separation between the second lens group and the third lens group grows wide; upon focusing from a focusing-on-infinity state to a close-range focusing state, the fourth lens group moves in an optical axis direction; and Conditions (1) and (2) are satisfied at the wide-angle end.

Abstract: A taking lens system includes, in order from an object side thereof, a first lens group (negative refracting), a second lens group (positive refracting), an aperture stop and a third lens group (positive refracting). Focusing from an infinite distance to a finite distance is performed by setting the second lens group and the third lens group such that the position of the second lens group upon focusing on a finite distance is located on an image side of the taking lens system with respect to the position of the second lens group upon focusing on an infinite distance and the position of the third lens group upon focusing on a finite distance is located on an object side of the taking lens system with respect to the position of the third lens group upon focusing on an infinite distance, while the first lens group remains fixed.

Abstract: The invention relates to a taking lens system with a leadoff negative lens group wherein entrance of dust into a lens barrel upon focusing is prevented and fluctuations of aberrations with focusing are minimized, and a imaging device that incorporates the same. The taking lens system comprises, in order from an object side thereof, a first lens group G1 having negative refracting power, a second lens group G2 having positive refracting power, an aperture stop S and a third lens group G3 having positive refracting power.

Abstract: The invention relates to a space-saving yet high-quality real image type finder indicator wherein an optical member such as a hologram is used for a device for indicating various information in a finder. In a finder optical system has an objective system, an image erection system and an eyepiece system; A hologram H is provided on a reflecting surface of the image erection system, so that an image at an indication portion is indicated by hologram H in visual field of the finder.

Abstract: The invention provides an inexpensive yet lightweight front converter lens system which is improved in terms of performance by use of a diffractive surface. A front converter lens system CL mounted on a subject-side of a master lens system ML to convert its focal length comprises at least two lens groups, each comprising a diffractive surface r.sub.1 or r.sub.2.

Abstract: The invention relates to a high-performance zoom lens system which can use a diffractive surface therein for use with an image sensor having a number of pixels. The zoom lens system includes at least a first lens group G1 having positive power and a second lens group G2 having negative power between an object side of the system and an aperture stop S. The first lens group G1 includes at least one diffractive surface r.sub.1, and satisfies the following condition:0.001<f.sub.S /f.sub.DOE <0.025 (1)Here f.sub.S =.sqroot.f(f.sub.W .times.f.sub.T) wherein f.sub.W and f.sub.T are focal lengths of the zoom lens system at its wide-angle end and its telephoto end, respectively, and f.sub.DOE is a focal length of the diffractive surface r.sub.1.

Abstract: The invention has for its object to reduce the overall length of a single lens using a diffractive optical element, and provides a diffractive optical element applicable to an optical system for cameras such as silver salt cameras, and electronic cameras, in which both surfaces of the single lens are constructed of diffractive surfaces, are plane surfaces or have curvature, and comprise diffractive surfaces having, in order from a subject side thereof, positive power and positive power, positive power and negative power, and negative power and positive power.

Abstract: The invention provides a compact yet high-zoom-ratio zoom lens system for use with lens shutter cameras, which is well corrected for aberrations albeit being made up of a small number of lenses. The zoom lens comprises a first lens group G1 of positive refracting power, a second lens group G2 of positive refractive power and a third lens group G3 of negative refracting power. The lens groups move for zooming from the wide angle side to the telephoto side, with a separation between the first and second lens groups becoming wide and a separation between the second and third lens groups becoming narrow. At least one lens group has a diffractive surface therein, and satisfies 1.8<.beta..sub.T /.beta..sub.W <4.0 where .beta..sub.T and .beta..sub.W are transverse magnifications of the lens group having a diffractive surface at the wide-angle end and the telephoto end of the lens system.

Abstract: A single lens of high performance and high image quality has a diffractive optical element and, more particularly, an optical system best suited for use on optical instruments for which chromatic aberrations must be corrected, e.g., silver halide or electronic cameras. The optical system has one positive lens and a stop. At least one surface of the positive lens is constructed of a diffractive surface r.sub.1, and satisfies the condition 3<f.sub.D /f<30 where f.sub.D is a focal length of the diffractive surface, and f is a focal length of the entire lens system.

Abstract: The overall length of a lens, particularly the thickness thereof, is reduced to thereby reduce the volumetric capacity occupied by a lens system for distance measurement. A distance measuring apparatus has a light-emitting device; a light-projecting lens system for projecting light emitted from the light-emitting device onto a subject; a light-receiving lens system for receiving and converging reflected light from the subject; and a detector for detecting the light. The light-projecting lens system or the light-receiving lens system includes a diffractive optical element having plane surfaces r.sub.1 and r.sub.4 on both sides thereof, at least one of which is formed from a diffraction surface. A similar diffractive optical element is provided in a similar lens system adapted to change a projected light angle by adding a converter lens to a master lens, and also provided in a similar lens system adapted to change a projected light angle by changing the spacing between a plurality of lens units.

Abstract: A two-unit zoom lens system having a front lens unit of positive refractive power, and a rear lens unit of negative refractive power. The zoom lens system has a reduced number of constituent lens elements, and yet provides a zoom ratio of nearly 3 and favorable performance at reduced cost. The zoom lens system has a front lens unit (G.sub.F) of positive refractive power, and a rear lens unit (G.sub.R) of negative refractive power. Zooming is effected by varying the spacing between the two lens units. The front lens unit has a first lens component (G.sub.F1) of negative refractive power, and a second lens component (G.sub.F2) of positive refractive power. The first lens component includes no positive lens element, but has at least one aspherical surface. The second lens component includes a negative lens element and a positive lens element, which are disposed in the mentioned order.

Abstract: The invention provides a two-unit zoom lens system comprising a front unit G.sub.F of positive refracting power and a rear unit G.sub.R of negative positive power which achieves a zoom ratio as high as about 3 with the use of a reduced number of lenses, and in which the spacing between both units is varied for zooming, said front unit including on the side proximate to the object a first lens component G.sub.F1 comprising a lens of plastic material having weak power, said first lens component including at least one aspheric surface, said rear unit including at least one positive lens and at least one negative lens, and said zoom lens system conforming to 0.2>.vertline.f.sub.W /f.sub.F1 .vertline. and 1.65<N.sub.RN where f.sub.W is the focal length of the overall system at the wide-angle end, f.sub.F1 is the focal length of said first lens component, and N.sub.RN is the refractive index of the negative lens of said rear unit.