Abstract: A projection lens for enlargedly projecting the image of a cathode ray tube onto a screen comprises, in succession from the screen side, a first lens having a positive refractive power, a second lens having a positive refractive power and having its surface of sharper curvature facing the screen side, the second lens being disposed at or near the entrance pupil position of the entire system, a biconvex third lens having a positive refractive power, and a fourth lens having a negative refractive power and having its surface of sharper curvature facing the screen side.

Abstract: A wide angle zoom lens comprising, in succession from the object side, a divergent lens group and a convergent lens group and in which magnification change is effected by relative movement of the two groups is characterized in that the divergent lens group has a positive lens and at least one negative lens formed of a low-index high-dispersion material having a refractive index of 1.5 or less and an Abbe number of 62 or less.

Abstract: A wide angle zoom lens system comprises a forward group which is a divergent lens group, and a rearward group which is a convergent lens group. The divergent lens group includes, in succession from the object side, at least two negative meniscus lenses having their convex surfaces facing the object side and only one positive meniscus lens having its convex surface facing the object side. The convergent lens group has, in succession from the object side, a biconvex positive lens having its surface of sharper curvature facing the object side, a single or doublet positive lens having its surface of sharper curvature facing the object side, a biconcave negative lens having its surface of sharper curvature facing the image side, a positive meniscus lens having its convex surface facing the image side, and a positive meniscus lens having its convex surface facing the object side. The lens system satisfies predetermined conditions.

Abstract: This specification discloses a zoom lens which comprises, in succession from the object side, a divergent lens group and a convergent lens group and whose magnification is changed by relative movement of the two groups. The divergent lens group comprises, in succession from the object side, three continuous negative meniscus lenses having their respective convex surfaces facing the object side and a positive lens having its surface of sharper curvature facing the object side. The convergent lens group comprises, in succession from the object side, a single biconvex positive lens, a meniscus lens comprising a doublet and having its convex surface facing the object side, a positive lens, a negative lens and two continuous positive lenses. The zoom lens satisfies predetermined conditions.

Abstract: An inverted telephoto type wide angle lens comprises, in succession from the object side, a divergent first group, a diaphragm-forward convergent second group and a diaphragm-rearward convergent third group. The first group includes a positive meniscus lens having its convex surface facing the object side, and three negative meniscus lenses having their convex surfaces facing the object side. The second group includes two positive lenses, a negative meniscus lens having its convex surface facing the object side, and a positive lens. The third group includes a positive meniscus having its convex surface facing the image side, a doublet biconcave negative lens and two positive lenses. The lens system satisfies certain conditions.