Abstract: A zoom lens of a compact size and good performance comprises a front diverging lens group and a rear converging lens group which are mechanically movable for variable power, the front diverging lens comprising a first lens of negative meniscus which is convex toward an object, a second negative lens, and a third lens of positive meniscus which is convex toward the object, the rear converging lens comprising a fourth positive lens, a fifth positive lens, a sixth negative lens, and a seventh positive lens, there being an aperture disposed more closely than the rear group to the object and movable with the rear group.

Abstract: A zoom lens of a compact size and good performance comprises a front diverging lens group and a rear converging lens group which are mechanically movable for variable power, the front diverging lens comprising a first lens of negative meniscus which is convex toward an object, a second negative lens, and a third lens of positive meniscus which is convex toward the object, the rear converging lens comprising a fourth positive lens, a fifth positive lens, a sixth negative lens, and a seventh positive lens, there being an aperture disposed more closely than the rear group to the object and movable with the rear group.

Abstract: A retro-focus type wide-angle lens which has a large angular field of 76.degree. to 90.degree. and secures a sufficient amount of corner illumination comprises only five sets of lens elements including eight or nine lens elements. The first set of convergent lens located on the object side is a positive lens. The first set of divergent lenses comprises two or three separate negative lenses. The second set of convergent lenses comprises two separate positive lenses. The third set of convergent lens comprises a positive lens. These sets of lenses are designed so as to satisfy various numerical conditions as defined in the specification.

Abstract: A bright telephoto lens having a small telephoto ratio and with a properly compensated secondary spectrum which would otherwise largely affect the image-forming ability of the lens. The telephoto lens has a convergent lens group on the opposite side and a divergent lens group on the image side. The convergent group includes first, second and third positive lenses and a single negative lens, the first positive lens being closest to the object and made of an optical material having a partial dispersion ratio in the range of from 1.22 to 1.29 with respect to g-line and d-line. The negative lens is disposed more closely to the image than the first positive lens. The second and third positive lenses are disposed more closely toward the image than the first positive lens and are made of an optical material of anomalous dispersion having a partial dispersion ratio in the range of from 1.22 to 1.24 with respect to g-line and d-line, and have an Abbe number .nu..sub.d which ranges from 80 to 95.5.

Abstract: A zoom lens comprising a first lens component having a positive refractive power, a second lens component having a negative refractive power, a third lens component having a negative refractive power, and a fourth lens component having a positive refractive power, the first through fourth lens components being arranged in order from an object.

Abstract: A compact, five-element, high-performance behind aperture lens system comprising a positive-meniscus first lens, a negative second lens, a positive third lens, a double-concave negative fourth lens, and a double-convex positive fifth lens in the order from the object side.