Wide angle, deep field, close focusing optical system

摘要

An optical system having the features of a wide angle lens, a deep field lens and a close focusing lens in comprised of an objective lens, a field lens and a relay lens aligned on an optical axis in that sequence for the objective lens to form an intermediate image at or near the field lens and for the field lens and relay lens to transmit that same image to a smaller final image at the plane of the film of a film camera or charge coupled device of a video camera. The objective lens preferably has a fixed focal length and a wide open aperture for forming the intermediate image of a larger size than is otherwise normal for an objective lens of that focal length. Preferably, the relay lens has the iris and focusing mechanism whereby the objective lens andfield lens are not required to be used for aperture control and focusing. The optical system provides an extended optical axis for accommodating lighting of a near object being photographed. In modifications of the basic optical system, the optical axis is turned 90 DEG one or more times and rotatable joints are provided in the lens barrel for versatile positioning of the objective lens relative to the camera with appropriate prisms for inverting and reversing the orientation of the final image at the film or CCD detector plane.