Abstract: A separate set of aperture blades is provided for varying the maximum full aperture of a zoom lens as its magnification is changed. The second set of aperture blades are pivotally mounted to a support plate which also rotatably supports the conventional aperture blades.

Abstract: A wide-angle lens system for compact color video cameras composed of nine lenses grouped in eight lens components. A first lens component includes a negative meniscus lens convex toward the object, a second lens component includes a positive meniscus lens concave toward the object, a third lens component includes a negative meniscus lens convex toward the object, a fourth lens component includes a positive cemented lens composed of a positive lens and a negative lens, a fifth lens component includes a positive lens, a sixth lens component includes a negative lens, a seventh lens component includes a positive lens and an eighth lens component includes a positive lens.

Abstract: A large-aperture single lens with aspherical surfaces to be used as a pickup lens for video disks, especially for tracking the video disk by directly moving the pickup lens. It is preferable that the single lens is made of plastic material in order to make it compact and light in weight. Both refractive surfaces of the single lens are arranged to have positive refractive powers in order to make the working distance of the lens long. Spherical aberration of the single lens is corrected to the degree that the diameter of the circle of confusion thereof is decided approximately by diffraction of light. Both refractive surfaces of the single lens are formed as aspherical surfaces and the shapes of the refractive surfaces are determined so as to correct aberrations including the sine condition to the required range, by taking the error to be caused at the time of manufacture into consideration.