Abstract: A high relative aperture objective lens system with a compound focusing system, comprising four lens components of varying respective distances, in which the first component is of positive refractive power, the second component is of positive refractive power, the third component is of negative refractive power, and the fourth component is of positive refractive power. The lens system is designed so that focusing is produced by translating the second and fourth components, the aberrations--and notably coma--being well corrected throughout the whole focusing distance range.

Abstract: Two lens groups the distance between which is changed during zooming. The first lens group closest to the object has a positive focal length and comprises, from the object side, a negative length first lens unit of positive and negative elements, a second lens unit of at least one positive element and a positive focal length third lens unit of positive and negative elements. The second lens group has a negative focal length and comprises one positive and two negative meniscus elements. Eight conditions are imposed on the focal lengths, the refractive indices and the Abbe numbers.

Abstract: A high relative aperture Gauss type lens comprising, from front to rear, a first lens unit including at least one positive lens, a negative meniscus-shaped second lens convex toward the front, a positive third lens with its front surface of strong convex curvature toward the front, a negative fourth lens with its rear surface of strong concave curvature toward the rear, a negative fifth lens with its front surface of strong concave curvature toward the front, a positive sixth lens with its rear surface of strong convex curvature toward the rear, a negative meniscus-shaped seventh lens convex toward the rear, a positive meniscus-shaped eighth lens convex toward the rear, a positive ninth lens, and a positive meniscus-shaped tenth lens convex toward the front.