Abstract: A variable soft focus lens system particularly adapted for photography is provided. The soft focus lens system includes at least two lens groups defining a meniscus shaped air space there between. The relative width of the air space can be variable by movement of one of the lens groups relative to the other. This movement can introduce a controlled amount of spherical aberration to provide within certain parameters a soft focus image with an acceptable Petzval sum and flatness of the image plane. Various embodiments of the present invention within the inventive parameters can be utilized and include both stationary and variable soft focus lens system.

Abstract: An image forming optical system, such as a photographic objective lens assembly is provided with a movable optical element. The movable optical element is designed and mounted so that it can optically interact with the transmission rays of the optical system or permit the rays to pass unaffected. The optical element can be a filter capable of improving the image forming characteristics of target object image to provide an advantageous soft focus, for example, as a portrait lens system or to provide a soft defocussed image. The optical filter element can have a central region capable of passing the converging or diverging transmitted rays through the optical system substantially free of refraction and a peripheral region capable of decreasing the transmitted image point intensity of rays transmitted therethrough. The optical filter element can be movable along the optical axis within a predetermined range of movement.

Abstract: A retrofocus wide angle lens system provides an increased field angle with a large aperture ratio. Besides the specific arrangement of the individual lens components in the various embodiments of the present invention, the retrofocus wide angle lens design further satisfies the following conditions: ##EQU1## WHEREIN R IS THE RADII OF CURVATURES FOR THE SUCCESSIVE LENS SURFACES FROM THE OBJECT TO IMAGE SIDE OF THE LENS SYSTEM; N.sub.I and N.sub.II represent the refractive indices of lenses forming a cemented doublet on the image side of the diaphragm; R represents the common radius of curvature of an intermediate surface of the doublet and f represents the overall focal length of the lens system.

Abstract: A retro-focus type wide angle lens system comprises a negative first component located on the object side and including at least one negative meniscus lens; a positive intermediate second component consisting of one or two lens groups including at least one biconvex lens group and a rear third component which includes of four consecutive lenses including, in order, a positive meniscus first lens having a rear convex surface, a biconcave second lens, a positive meniscus third lens having a rear convex surface and a fourth positive lens; whereby the back focus of the total lens system is longer than the focal length, and satisfying the following conditions:(1)d.sub.c0 > d.sub.c2(2).vertline.r.sub.c2 .vertline..gtoreq. .vertline. r.sub.c3 .vertline.(3)V.sub.c1 > V.sub.c2(4)d.sub.c0 > d.sub.c4whereinr.sub.c2 and r.sub.