Abstract: A zoom lens including, from front to rear, a first lens group of positive power, a second lens group of negative power, a third lens group of positive power, a fourth lens group of negative power, and a fifth lens group of positive power. For zooming from the shortest focal length to the longest focal length, the first lens group is moved forward, the air space between the first and second lens groups is increased, the air space between the second and the third lens groups is decreased, the air space between the third and fourth lens groups is increased, and the air space between the fourth and fifth lens groups is decreased. The fifth lens group remains stationary during zooming. This construction and arrangement results in a zoom lens of compact form with a large aperture while still permitting good stability of aberration correction throughout a greatly extended zooming range.

Abstract: The disclosed zoom lens has at least four lens groups with proper refractive powers operating such that while the third lens group counting from front is held stationary, the first and second lens groups and at least one of the fourth lens group and those that follow are moved axially in differential relation to effect zooming. A given range of variation with zooming of the image magnification of the second lens group and a given differential relation for the zooming movement of the first and second lens groups achieve good stability of aberration correction over an extended zooming range.

Abstract: The disclosed zoom lens includes, from front to rear, a magnification-power variable lens assembly which serves for zooming and an image forming lens assembly which is stationary during zooming. The image forming assembly has a lens component B of negative refractive power which is preceded by at least one lens component A movable for focusing and which is followed by at least one lens component C movable for focusing. This structure makes achievement of a compact form and good stability in aberration correction possible throughout the entire focusing range.

Abstract: In the disclosed photographic objective, a focusing lens group is arranged on the image side of a stop. To focus, all or part of the lens group, or the stop and all or part of the lens group, are moved to maintain an exit pupil at a substantially constant position.

Abstract: A zoom lens having at least four components of which the 1st counting from the object side is of positive power, the 2nd is of negative power and the 3rd and 4th are of positive or negative power, wherein the 2nd component is made fixed, and the 1st component and at least one of those that follow the 2nd component are made movable for zooming, whereby the bulk and size of the lens system is minimized, while still permitting good correction of aberrations.

Abstract: A zoom lens system having, from front to rear, a positive first component, a negative second component, a positive third component and a fourth component, in which to effect zooming, the first, second and third components are moved axially in A relation such that the movements of the first and second components are non-linear with respect to that of the third component, and that when in the telephoto end, the first and third components lie more toward the front and the second component lies more toward the rear than when in the wide angle end. By specifying the relation in which the first, second and third components move as zooming nears the wide angle end, a valuable decrease in the diameter of the front lens members is achieved to provide a compact zoom lens system.

Abstract: The disclosed finder includes an optical system having an optical axis and an image plane, an eyepiece lens conjugately arranged at the rear to observe the image plane, a plurality of lens units, and a reflecting mirror arranged between the successive two of the lens units, to obtain an erect image and to shorten the total finder length.

Abstract: A zoom lens with a frontmost lens group made to have the focusing function, said focusing lens group being provided with at least one member made of a plastic material. The other part of the lens system than the focusing lens group is constructed with lenses made of materials which assure that the focal length will not vary with variation of the surrounding temperature and humidity so that when focusing is followed by zooming displacement of the image plane can be prevented.

Abstract: A zoom lens having at least three components, or, from front to rear, a first component of positive power, a second component of negative power and a third component with the air separations between the successive two of said three components being varied to effect zooming, whereby said first component is constructed with, from front to rear, a bi-convex first lens, a second lens of negative power and a third lens of positive power.

Abstract: A zoom lens having at least 4 components of which the 1st component counting from the front is of positive refractive power and the 2nd and 3rd components are of negative refractive power, wherein the aforesaid 1st, 2nd and 3rd components are made movable for moving in respective loci, which are different from each other, to effect zooming.

Abstract: An in-focus position detecting optical system comprises a focus lens for imaging the image of an object to be photographed at an imaging position. The focus lens has integrally formed therewith a light projecting lens for projecting a distance measuring light flux onto the object to be photographed. The light projecting lens has the same focal length as that of the focus lens.

Abstract: The disclosed zoom lens includes, from front to rear, a first lens component of positive power for focusing the lens, a second lens component of negative power for varying magnification power, a third lens component of negative power for compensating for the image shift resulting from the change of magnification power, and a fourth lens component of positive power for forming an image. The second lens component includes, from front to rear, a negative meniscus-shaped lens having a strong refracting rear surface, and another negative mensicus-shaped lens having a strong refracting front surface and a cemented surface of forward convexity. A front group of the fourth component includes, from front to rear, a bi-convex lens having a rear surface of strong curvature, another bi-convex lens having a front surface of strong curvature, a lens of negative power having a front surface of strong curvature and a lens of positive power having a front surface of strong curvature.

Abstract: Disclosed is a video camera in which the field of view of an automatic focusing device is displayed on an electronic view finder, and the displayed field of view is adjustable in accordance with the object distance and/or the zooming state of the lens system.

Abstract: A picture taking optical system for a color video camera of the frequency dividing type in which a half mirror for automatic focus detection and a double refraction plate for use as an optical low pass filter are in proper relation to prevent a reduction in the performance of the low pass filter.

Abstract: A photographic optical system including a beam splitter for a finder is provided with a releasably attached extender in between the beam splitter and a focal plane, while the finder is provided with means for changing the magnification of an image thereof as the extender is inserted into, or retracted from, axial alignment to the optical system. The camera has, despite the addition of the magnification power changing capability along with the finder image magnification correcting capability, to be made small in the size and light in the weight.

Abstract: A zoom lens having, from front to rear, a 1st lens group having a positive refractive power for focusing, a 2nd lens group of negative refractive power having a magnification changing function, a 3rd lens group having a negative refractive power for compensating for the image shift resulting from the change of the magnification, and a 4th lens group of positive refractive power having an image forming function, the aforesaid 4th lens group having two lens groups with the front or 4-1st lens group and the rear or 4-2nd lens group. The form and construction and arrangement of the lens elements of the aforesaid 4-1st and the aforesaid 4-2nd lens groups are properly set forth so as to achieve good correction of aberrations and, at the same time, limiting the bulk and size of the entire system to a minimum.

Abstract: A zoom objective comprising four lens groups of which the first three lens groups counting from the object side are movable for zooming, whereby the refractive powers and the conditions of zooming movement of the aforesaid three lens groups are properly specified so as to improve the compactness while still maintaining good correction of aberrations.

Abstract: In a telephoto objective, a positive lens group and a negative lens group closer to the image than the positive lens group move simultaneously in axially opposite directions and relative to a stationary positive lens group which is closer to the image than both movable lens groups while the telephoto objective is being focused on an object. According to one embodiment of the invention, the diaphragm between the movable lens groups is varied in response to focusing so as to control the variation of the diameter of an on-axial light ray bundle.

Abstract: In the disclosed light metering device, a scanning reflecting mirror directs a portion of light that has passed through an objective lens to a light-sensitive element and a driving device changes the positional relationship of the light-sensitive element and the reflecting mirror for light metering relative to each other so as to scan the image format formed by the objective lens. A weighting arrangement gives light metering outputs different weights corresponding to the scanning positions in the image format. This forms a light-metering weighting device in the camera.

Abstract: An optical low-pass filter is comprized of micro stripe prisms arranged on the surface of a transparent member. A transmissive medium which is of different refractive index from that of air is used to fill the grooves of the microprisms to permit the arrangement to have micro stripe prisms with a large vertex angle.