Abstract: A varifocal forward lens group of a camera objective, with a pair of axially shiftable negative components bracketed by a pair of substantially fixed positive components, has its negative third component more widely separated from its positive fourth component in a wide-angle position of minimum overall focal length than in a telephoto position of maximum overall focal length. The effective diameter of that third component is just large enough to let a bundle of axially incident light rays fully illuminate the fourth component in the wide-angle position, with less than full illumination in the telephoto position. The positive first component is also just large enough to provide full illumination of the effective area of the third component by axial rays in the telephoto position.

Abstract: A zoom objective is disclosed which consists of a varifocal front lens group and a fixed rear lens group, the front lens group comprising a stationary first component of positive refractivity, axially shiftable second and third components of negative refractivity, and a stationary fourth component of positive refractivity separated from the rear lens group by a reflex prism adjoining a diaphragm space. The assembly of third and fourth components, prism and rear lens group can be selectively combined with various first and second components to provide zoom objectives of different varifocal ratios.

Abstract: A basic lens for a pancratic camera lens system having an afocal screen of variable enlargement in which the screen includes a primary, positive front component, second and third negative components, the total focal length of the second negative component being displaceable of the optical axis and the minimum focal length of the second negative element and the image field diagonal 2.sub.y having a relationship (f.sub.Gmin - f.sub.II)<6y, and a fourth positive component, the basic lens being constructed in the form of an assembly of six lenses including, in succession beginning with the lens facing the object to be photographed, a first biconvex lens, a second biconvex lens, a first biconcave lens cemented to the second biconvex lens, a second biconcave lens, a third biconvex lens and a positive meniscus, all arranged in aligned relationship in the direction of light incidence.

Abstract: A varifocal objective has an axially shiftable positive front component, an axially shiftable negative intermediate component, and a fixed positive rear component or basic lens group. The latter component consists of five closely spaced lens members, all but the second of them singlets and all but the third of them positively refracting. The intermediate component is separated from the rear component by a diaphragm space which in a position of close approach of these components, corresponding to maximum focal length, is still substantially greater than any air space between the lens members of the rear component. With a varifocal ratio close to 3:1, the distance between the front and rear components is the same in the positions of maximum and minimum focal lengths.