Abstract: A bright and compact optical-compensation type zoom lens system comprising a first lens group I having positive refractive power, a second lens group II having negative refractive power, a third lens group III having positive refractive power, and a fourth lens group IV having positive refractive power, the zoom lens system being arranged to carry out zooming by keeping the lens groups II and IV fixed and moving the lens groups I and III, the zoom lens system being arranged so that the focal length in the tele-position is long and, moreover, the quality of image is good.

Abstract: A zoom lens system comprising a front lens group consisting of a first positive lens component, a second negative meniscus lens component, a third negative lens component and a fourth positive lens component, and a rear lens group consisting of a fifth positive lens component, a sixth positive lens component, a seventh negative lens component and an eighth positive lens component. Said zoom lens system is so adapted as to perform zooming operation by varying the airspace reserved between said front and rear lens groups, and has sufficient wide-angle effect and a large zooming ratio in addition to aberrations corrected with good balance.

Abstract: A wide-angle zoom lens system comprising a front lens group consisting of a first negative meniscus lens component, a second negative lens component and a third positive lens component, and a rear lens group consisting of a fourth positive lens component, a fifth positive meniscus lens component, a sixth negative lens component and a seventh positive lens component. Said zoom lens system is so adapted as to permit changing focal length of the entire lens system as a whole by varying the airspace reserved between said front and rear lens groups, and has a wide field angle of 73.4.degree. at the wide position, a high zoom ratio of 1.62 and an aperture ratio of F/3.2 assuring brightness sufficient for practical use.

Abstract: An apparatus for measuring a range to a subject comprising a first optical system for forming a first stationary image of the subject on a first photosensitive element such as a photosensor array, a second optical system for forming a second image of the subject on a second photosensitive element, said second image being shifted with respect to the first stationary image by rotating a rotatable scanning mirror of the second optical system, and a pin hole member having first and second pin holes formed therein and arranged in front of the first and second photosensitive elements in such a manner that the pin hole member can be moved in a direction parallel to optical axes of the first and second photosensitive elements as well as in a plane perpendicular to the optical axis so as to change a size and a position of a range measuring area with respect to a field of view.

Abstract: An albada finder incorporating a range finder comprising a first negative lens component, a second thick negative lens component and a third positive lens component, said second lens component being split into two elements along a plane inclined with regard to the optical axis and a semitransparent surface being formed on said split surface.

Abstract: A wide-angle retrofocus lens system comprises a first lens component comprising a positive meniscus lens having its convex surface on the object side, a second lens component comprising a negative meniscus lens having its convex surface on the object side, a third lens component comprising a positive cemented lens component of a positive lens and a negative lens, a fourth lens component comprising a negative lens, a fifth lens component comprising a positive meniscus lens having its convex surface on the image side, and a sixth lens component comprising a positive lens. The system is arranged to satisfy the predetermined conditions so that, despite the use of a small number of component lenses, the overall length of the system can be made short, the back focal length long and various aberrations are well-corrected over a wide angle of image field.

Abstract: A focusing optical system for single-lens reflex cameras comprising an auxiliary lens arranged in the vicinity of the focusing surface of a focusing glass and a detector element arranged in the vicinity of a penta-prism, and so adapted as to detect the focusing point by transferring a portion of the light from an object to said detector element.

Abstract: A photographic lens system of modified Gauss type having five-component six-element lens configuration for which the field angle is 41.degree. to 53.degree., aperture ratio is F1:2, overall length is short, back focal length is long and aberrations are corrected favorably.

Abstract: A finder optical system for single-lens reflex photographic cameras wherein an even number at least four of small reflecting surfaces are arranged in front of a pentagonal prism of a single-lens reflex photographic camera in such a way that an image of optical information such as graduations on diaphragm dial or shutter speed dial is reflected consecutively by said small reflecting surfaces, whereafter said image of optical information is projected around the field of view in a finder, said finder optical system being capable of projecting an image of optical information free from difference in dioptor at any desired position around said field of view in the finder by changing locations and/or relative tilting angles of said small reflecting surfaces.

Abstract: A variant Ernostar type long focus lens system having a very short overall length comprising a first positive miniscus lens, a second positive meniscus lens and a third positive meniscus lens which are arranged very close to one another, a fourth negative meniscus lens and a fifth positive meniscus lens, and said lens system having a focal length of 180-200 mm and a telephoto ratio of approximately 0.93.

Abstract: An ultra-high resolution reducing lens system comprising a lens group I having negative refractive power and a lens group II having positive refractive power which are arranged by providing a large airspace between them. The ultra-high resolution lens system is compactly designed but has a long working distance. Moreover, the quantity of light does not decrease in the marginal portion of the field, resolution is high, aperture ratio is F1.0 and magnification is .times.1/100.