Abstract: The disclosed zoom lens employs rear focusing with inclusion of two lens portions, or a varifocal portion and a focusing portion arranged respectively from front (object) to rear (image). The components of the varifocal and focusing portions are arranged such that for a given finite object distance, the position of an image plane of the entire system is maintained constant despite zooming of the varifocal portion.

Abstract: The disclosed zoom lens has at least three components and three components are made movable for zooming to different object distances by axially moving two of said components as a unit.

Abstract: A zoom lens comprising, from front to rear, a first zoom section and a second zoom section, the first zoom section having a plurality of movable lens units which simultaneously move to effect zooming, and the second zoom section having a plurality of axially movable lens units, the light beam exiting from the rearmost unit in the first section enters directly the frontmost unit in the second section, and the refractive powers of the front and rear lens units are made positive and negative respectively, whereby the front and rear lens units are simultaneously moved in such a way that the magnifying power of the rear lens unit remains positive when the focal length of the entire system varies.

Abstract: A zoom lens which performs focusing by using part of a movable lens unit. In zooming, a lens unit V for changing the focal length of the entire system and another lens unit C for maintaining the constant position of an image plane move in certain relation to each other. For all objects in the focusing range, a part of either the aforesaid lens unit V or the aforesaid lens unit C is made to move to effect focusing at any station in the entire zooming range, thereby the zoom lens can be constructed in compact form.

Abstract: A zoom lens having a plurality of lens units with the air separations, at least one of which is varied to effect zooming, the rearmost lens surface of successive two of the lens units and the frontmost lens surface of the rear one being both formed to convex shapes toward the front, whereby when these two lens units axially move at different speeds from each other, a soft-focus effect of varying magnitude is produced on the image.

Abstract: A zoom lens comprising two or more lens units axially movable for magnifying in front of a lens unit of negative power which remains stationary during zooming, wherein at least one of the magnifying lens units and the lens unit of negative power are simultaneously moved axially to effect focusing.

Abstract: A zoom lens including, from front to rear, a positive first component, a negative second component, a positive third component and a fourth component which is stationary during zooming. In some zoom lenses, a fifth component may be positioned behind the fourth component, in which, during zooming, the fourth component is movable and the fifth component is stationary. The separation between the first and second components and the separation between the second and third components varies to effect zooming. The third component is composed of, from front to rear, two positive lenses, a negative meniscus lens having a divergent cemented surface convex towards the front, and a positive lens with its rear surface having the stronger curvature. Minimization of bulk and size and an increase of the image magnification range of the zoom lens is achieved while preserving correction if aberrations.

Abstract: The disclosed photographic optical system with a focus detector is constructed with an objective lens portion and an optical path splitting surface arranged on the image side thereof. An optical element and an image receiver are successively arranged on one of the split optical paths. A beam source for projecting an object sensing beam in the infrared wavelength region, or a photo-sensor for sensing the reflection of the object sensing beam from an object is arranged on the other split optical path. The spectral transmittance characteristic of the objective lens portion is different from that of the optical element, and is constructed to pass the wavelength region of the object sensing beam. The superimposed characteristic of the spectral transmittance characteristic of the objective lens portion and the spectral transmittance characteristic of the optical element are matched with the sensitivity characteristic of the image receiver.

Abstract: A zoom lens including, from front to rear, a first lens unit of negative power and a second lens unit of positive power with the separation therebetween being varied to effect zooming. The first lens unit is moved to effect focusing, wherein with the first lens unit focusing a finite object distance on the wide angle side, the second lens unit moves rearward to obtain focal lengths beyond the zooming range.

Abstract: A zoom lens having a component V which has at least one group of lens elements axially movable mainly for changing image magnification, a component C which has at least one group of lens elements axially movable for compensating for the image shift resulting from the change of image magnification to maintain the constant position of the image plane, and a compound component F positioned on the image side of either, or both, of said component V and said component C to be movable with zooming, and having a plurality of lens groups contributing to a small overall refractive power, whereby the focusing provision is made in at least one of the groups in said compound component F.

Abstract: The disclosed zoom lens includes, from front to rear, a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power, and a fourth lens unit. When zooming, the first and third lens units are axially moved independently of each other, the second lens unit remains stationary, and the fourth lens unit is axially moved but changes the direction of advance at an intermediate point in the zooming range.

Abstract: A zoom lens is constructed, from front to rear, of a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power and a fourth lens unit of positive or negative power. When zooming from the wide angle to the telephoto end, the first and third lens units move forward at the same speed, while the second lens unit moves simultaneously in non-linearly differential relation to the first and third lens unit. The zoom lens satisfies the following conditions:0.4 fT<f1<0.65 fT0.4 fW<.vertline.f2.vertline.<0.25 fT0.12 fT<f3<0.35 fT-0.18<fW/f4fT/f4<0.10.8<.vertline..beta.2T.vertline.<1.0where f1 to f4 are the focal lengths of the first to the fourth lens units, respectively, fW and fT are the shortest and longest focal lengths of the entire zoom lens system, respectively and .beta.2T is the magnifying power of the second lens unit in the telephoto end.

Abstract: A zoom lens comprising, from front to rear, a negative first component, a positive second component, a positive or negative third component and a positive fourth component. To effect zooming, the first, second and third components are made to axially move in differential relation to each other. This makes it possible to achieve a minimization of the bulk and size of the entire system and a valuable increase in the angle of view field for the wide angle setting.

Abstract: A compact zoom lens including, from front to rear, a first lens unit of positive power, a second lens unit of negative power, a third lens unit of positive power and, if desired, further a fourth lens unit, with the separations between the first and second units, between the second and third units and between the third and fourth units being made variable to vary the focal length of the entire system, wherein as the focal length is varied from the shortest to the longest value, the first and third units move axially forward, and the third unit is provided with a positive lens having an aspherical surface.

Abstract: The disclosed zoom lens is composed of four lens groups. Counting from the front, the first lens group has a positive power, the second a negative power, the third a positive power and the fourth a positive or a negative power. At least the first, third and fourth lens groups are movable for zooming. The zoom lens satisfies the following conditions:-3<.beta.3w<-0.8-0.35<f3/f4<0.430.5<Z2/Z<11<f1/fw<1.70.3<.vertline.f2.vertline./fw<0.48where fi is focal length of the i-th lens group, Z2 is the amount of variation of the magnification power of the second lens group with zooming, .beta.3W is the magnification power of the third lens group in the wide angle position, fw is the shortest focal length of the entire system, and Z is the zoom ratio of the entire system.

Abstract: A zoom lens includes, from front to rear, a positive first component, a negative second component, a positive third component and a positive or negative fourth component. The first, third and fourth components are movable to vary the focal length of the entire system. In the wide angle position, the image modification of the third component contributes to the ratio of the focal length of the third component to the focal length of the fourth component, and the ratio of that fraction of the zoom ration of the entire system which the second component assumes to the zoom ratio of the entire system, satisfies specific conditions such that minimization of the bulk and size of the zoom lens and a stabilized correction of aberrations are achieved.

Abstract: A zoom lens having a lst lens component of negative power counting from front, and a 2nd lens component of positive power, with an air separation therebetween being varied to effect zooming, wherein said 2nd component is divided into two components one of which is made movable for focusing, thus minimizing the bulk and size of the entire system, while still achieving good correction of aberrations.

Abstract: A lens system having three lens groups, or, from front to rear, a 1st lens group having a positive refractive power, a 2nd lens group having a negative refractive power, and a 3rd lens group having a positive refractive power, whereby a proper optical arrangement for said 1st, 2nd and 3rd lens groups and proper rules of design for each lens group are set forth and the aforesaid 3rd lens group is made movable for focusing, to thereby achieve good correction of aberrations.