Abstract: A mount shift apparatus of a lens for a CCTV camera includes a mount frame which is provided with a threaded portion which can be screw-engaged by a body mount of a camera body, a lens frame which supports a photographing lens group and which is supported to move relative to the mount frame in a direction perpendicular to the optical axis, and a mount shift device which adjusts the position of the lens frame with respect to the mount frame in the direction perpendicular to the optical axis.

Abstract: In a concentric ND filter in which multi-layered circular ND filter elements whose diameter is decreased stepwise toward the uppermost layer from the lowermost layer are concentrically provided on a first transparent substrate, a surrounding space of the concentrically multi-layered ND filter elements defined by and between the surface of the transparent substrate and the surface of the central ND filter layer of the smallest diameter is filled with a transparent adhesive.

Abstract: A color separation prism assembly includes an imaging lens, a blue light separation prism, a red light separation prism and a green light transmission prism, arranged in this order behind the imaging lens. A blue light reflecting dichroic layer is located between the blue light separation prism and the red light separation prism. A red light reflecting dichroic layer is located between the red light separation prism and the green light transmission prism. The prism assembly satisfies the relationships defined by20.degree.<.alpha.<22.degree.;and35.degree.<.beta.<37.degree.,wherein .alpha. represents an angle defined between a light incident surface of the blue light separation prism, perpendicular to an optical axis of the imaging lens and the blue light reflecting dichroic layer, and .beta. represents an angle defined between a light incident surface of the red light separation prism, parallel to the blue light reflecting dichroic layer and the red light reflecting dichroic layer.

Abstract: An aberration correcting plate for a compatible interchangeable lens which can be detachably attached to a first camera body having a large resultant thickness of filters provided in front of an image pickup device and to a second camera body having a small resultant thickness of filters provided in front of an image pickup device is mounted to a rear end of the compatible interchangeable lens when the rear end is mounted to the second camera body. The aberration correcting plate is made of a parallel-plate whose refractive index N is greater than 1.7 or a lens of negative power. The sum of the thicknesses of the aberration correcting plate and the filters provided in front of the image pickup device of the second camera body is substantially identical to or smaller than the total thickness of the filters provided in front of the image pickup device of the first camera body.

Abstract: A lens barrel is provided having a screw mount. The lens barrel includes a mount ring having a threaded portion, which can be engaged by a corresponding screw mount of the camera body to which the lens barrel is to be attached, a focus adjusting ring which is rotatably supported by the mount ring, a barrel body which is screw-engaged by the focus adjusting ring to support a focus adjusting lens, a linear movement guide member which is rotatably supported by the mount ring to restrict the movement of the barrel body so as to move only in the optical axis direction of the focus adjusting lens, and a frictional resisting member which resists the rotational movement of the linear movement guide member relative to the mount ring.