Abstract: A zoom lens is known which has a first lens group having a negative refracting power and a second lens group having a positive refracting power arranged from an object side, a spacing between both the lens groups being varied to thereby vary magnification (variable power). In order to make such zoom lens compact, the refracting power of the negative lens group is intensified and the negative refracting power is arranged in a portion at the rear of the positive lens group. The portion in the positive lens group is composed of a set of positive and negative lenses, and at least one surface of the lenses is made to be an aspherical surface to correct aberrations.

Abstract: A semi-wide angle objective lens in accordance with the present invention comprises five groups of six lens elements including a front group and a rear group in which the front group has a first group which includes a single positive meniscus lens L.sub.1 with its convex surface directed toward the object side, a second group which includes a single negative meniscus lens L.sub.2 with its convex surface directed toward the object side, and a third group which includes a single positive meniscus lens L.sub.3 with its convex surface directed toward the object side; and in which the rear group has a fourth group which includes both a negative lens L.sub.4 with its front concave surface having a large curvature directed toward the object side and a positive lens L.sub.5 with its rear convex surface having a large curvature directed toward an image side with the fourth group lenses cemented together or arranged with an extremely small air space therebetween, and a fifth group which includes a positive lens L.sub.

Abstract: A retro-focus wide angle lens which, as viewed from the object side, includes a first lens group of a single negative meniscus lens with its convex surface directed to the object side, a second lens group consisting of a single biconvex lens, a third lens group consisting of a single biconcave lens and fourth and fifth lens groups each consisting of a single positive meniscus lens having a concave surface directed to the object side.