Abstract: In an electrophotographic copying apparatus, reflected light from an original subject is directed to a light receiving means, such as a photoconductive drum, through a slit. The apparatus includes an optical device, for example a zoom lens, positioned between the original subject and the photoconductive drum for varying the size of the optical image being passed through the slit. A shading board fixed adjacent to the photoconductive drum extends along a longitudinal direction of the optical image.

Abstract: A copying lens system composed of a four-unit-four-element configuration including, in order from the object side, a first lens element of positive meniscus having a convex surface directed toward an object, a second lens element of negative meniscus having a convex surface directed toward the object, a third lens element of negative meniscus having a convex surface directed toward an image, and a fourth lens element of positive meniscus having a convex surface directed toward the image. In this configuration, the first lens element and the fourth lens element have the same geometric shape, and are disposed symmetrically with respect to a central diaphragm stop. The second and third lens elements also have the same geometric shape, and are also disposed symmetrically with respect to the central diaphragm stop. This provides an overall symmetrical configuration which can compensate for various aberrations.

Abstract: A color separating optical apparatus is provided with a compensating members in order to compensate for the differences in output energy of the separated colors which is attributable to the particular spectral characteristics of the light source and the light receiver. In various embodiments, selectable masks are used to control the light flux, or the light source itself is controlled as to the number of lamps energized for each color.

Abstract: A wide-angle telecentric projection lens system for use in enlarged projection at a magnification of about 15-20, that has a brightness of about F.sub.NO 1:7, and which covers a wide field of up to about 25 degrees in terms of the half viewing angle. This is attained by a telecentric projection lens system that comprises, in order from the screen side to the chart side, a first lens group composed of a single positive lens element, a second lens group composed of either a single negative lens element or a positive lens cemented to a negative lens, and a third lens group composed of both a negative lens cemented to a positive lens and two or more positive lens elements, which lens system satisfies the following conditions (1) and (2):(1) -2.5<f.sub.I /f.sub.II <-0.5(2) 0.6<f.sub.III /f<0.95wheref: the focal length of the overall lens systemf.sub.I : the focal length of the first lens groupf.sub.II : the focal length of the second lens groupf.sub.

Abstract: A zoom lens comprising a first and a second lens component that are related to each other for zooming. The first lens component consists of four lens elements and has a positive focal length f.sub.I satisfying the condition 0.35<f.sub.I /f.sub.M <0.85, where f.sub.M is the focal length of the system at unit magnification. The second lens component consists of a negative miniscus lens and possibly a positive lens and has a negative focal length f.sub.II satisfying the condition, 0.7<-f.sub.II /f.sub.M <3.0.

Abstract: A color zoom copying apparatus is provided having a slide base which holds one lens group comprising part of a zoom lens system, and which can move in the optical axis direction of the zoom lens system. The apparatus includes structure for driving the slide base along the optical axis direction in accordance with the magnification of the zoom lens system, a movable lens frame which supports another lens group of the zoom lens system and which is supported on the slide base so as to move in the optical axis direction, and a first adjusting device for moving the movable lens frame relative to the slide base in order to correct deviations in the focus of the zoom lens system which occur as a result of variations in magnification, in accordance with displacement of the slide base.

Abstract: A copying zoom lens comprising, in order from the object side, a first lens unit having a negative focal length, a second lens unit having a positive focal length and a third lens unit having a negative focal length. An axial space between the first and second lens units and an axial space between the second and third lens units are varied while moving an overall lens system and keeping constant a distance between the object and an image surface, thereby performing a zoom effect. The first lens unit is composed of a single negative meniscus first lens element having a concave surface directed to the object. The second lens unit is composed, in order from the object, of positive second lens element, a negative third lens element, a negative fourth lens element and a positive fifth lens element to constitute a three-lens element subsystem. The third lens unit is composed of a single negative meniscus sixth lens having a concave surface directed to the image surface.