Abstract: A zoom lens system comprising a first lens group having positive refractive power and a second lens group having negative refractive power, and so adapted as to perform zooming from the wide position to the teleposition by narrowing the airspace reserved between the two lens groups. In said zoom lens system, at least one graded refractive index lens component is arranged in the second lens group, or at least one graded refractive index lens component is arranged in the first lens group and at least one aspherical surface is adopted in the second lens group.

Abstract: A zoom view finder comprising a plural number of lens units and so adapted as to perform zooming by displacing some of said lens units, said zoom view finder satisfying the following conditions: ##EQU1## wherein the reference symbol z represents zoom ratio of the lens system, the reference symbols .nu..sub.max and .nu..sub.min designate the maximum Abbe's number and the minimum Abbe's number respectively out of Abbe's numbers of said lens units, and the reference symbols P(.DELTA..gamma.).sub.max and P(.DELTA..gamma.).sub.min denotes the maximum and minimum values out of percentages of the chromatic aberrations of angular magnification relative to magnification levels.

Abstract: A zoom finder comprising a system for forming the image of a measuring field frame and a vari-focal system in the order from the object side and arranged that the apparent size of the measuring field frame varies at the time of zooming.

Abstract: A compact zoom lens system comprising a first lens unit having negative refractive power and arranged as a movable lens unit, a second lens unit having positive refractive power and arranged as a movable lens unit, and a third lens unit arranged as a fixed lens unit, the compact zoom lens system being arranged that the third lens unit comprises a meniscus lens which is concave toward the object side and that aberrations are corrected favorably.

Abstract: An electronic photographing apparatus including a photosensor for converting an optical image, which enters through an objective lens, to an electric signal, and two comparators to which a video signal obtained by signal-processing the electric signal is supplied. Supplied to the comparators, respectively, are a reference voltage slightly lower than the saturation level of the video signal and a reference voltage slightly higher than the black level of the video signal. The comparators convert the video signal to a binary signal according to the reference voltages. The binary signals are supplied to a video signal processing circuit and are converted to a binary video signal. When the binary video signal is supplied to the display of an electric finder, an image which is over- or/and underexposed is displayed on the display. When the binary signal is supplied to an automatic exposure unit, the exposure of the scene is automatically controlled according to the over- or/and underexposure.

Abstract: A zoom lens system comprising a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having negative refractive power and a fourth lens group having positive refractive power, the zoom lens system being arranged to be zoomed by moving the second and third lens groups, at least one lens element in the fourth lens group being arranged as a plastic lens, the zoom lens system being thereby arranged to be small in size, light in weight and low in price and, at the same time, to have high performance.

Abstract: An electronic camera has a solid-state image pick-up device for picking up an image incident thereon through an imaging lens. The camera has a half mirror interposed between the lens and the image pick-up device, and, at its lower portion, a screen and a lamp for generating an information image. The half mirror transmits the incident image through the lens, and reflects the information image. Both images are synthesized, and a superposed image becomes incident on the image pick-up device.

Abstract: There is an indicating device constituted so as to be apt to indicate the data such as the magnification ratio of an objective lens, the value of NA, the data or the like in the visual field of a microscope and at the same time to record these data in photograph. This indicating device is provided with a display means (17) able to indicate various sorts of data informations through the data processor (16) and polarizing prisms (10, 11) arranged between the objective lens (9), display means (17), photographing lens (14) and eyepiece (13) to divide the light bundle from the objective lens (9) and the light bundle from the data display means (17) respectively and to make them advance to the eyepiece (13) and photographing lens (14), and the data informations displayed on the display means (17) are imaged on the image forming face (12) inside the eyepiece (13) and on the dry-plate (15).

Abstract: A lens system for optically recorded disks comprising a first, second, third and fourth lens components in the order from the light-source side, the first lens component having positive refractive power, the second lens component having negative refractive power, the third lens component having positive refractive power, the fourth lens component having positive refractive power, the lens system for optically recorded disks having a large N.A., long working distance and wide field angle.

Abstract: An optical read-out lens system for optically recorded disks comprising a first, second, third and fourth lenses in which the first lens is a positive lens, the second lens is a negative lens, the third lens is a positive lens and the fourth lens is a positive meniscus lens, the optical read-out lens system comprising a small number of lenses, being light in weight and having large NA and long working distance.

Abstract: An optical read-out lens system for optically recorded disks comprising a first, second, third and fourth lenses in which the first lens is a negative meniscus lens, the second lens is a positive lens, the third lens is a positive lens and the fourth lens is a positive meniscus lens, the optical read-out lens system being arranged that the working distance is long and offaxial aberrations are corrected favorably and, moreover, arranged to be small in size, light in weight and low in price.

Abstract: An optical recording and read-out lens system for optical recording type disks comprising a first and second lens components, the first lens component being a cemented lens consisting of three lens elements, i.e., a biconvex lens, biconcave lens and biconvex lens, the second lens component being a positive meniscus lens, the optical recording and read-out lens system having large NA, long working distance and well corrected aberrations especially chromatic aberration, and being small in size and light in weight.