Fuji Photo Optical Co., Ltd.

Fujinon Corporation

Kazuo Yoshikawa

Hisao Takemae

Takami Hasegawa

Yoshikazu Doi

Seiji Toyama

Takeshi Higuchi

Katsuo Katagiri

Hideo Buto

An autofocus adapter for detachably mounting between an imaging lens and a camera body and for detecting the focus state of the imaging lens is disclosed. The autofocus adapter includes two focus state detecting elements with light receiving surfaces slightly displaced in front and in back of a desired position of focus of the imaging lens. A beamsplitter directs some light to the two focus state detecting elements and some light through the autofocus adapter for forming an image in a camera. The autofocus adapter includes a relay lens system and electronics for detecting the focus state and controlling the focus of the imaging lens to an in-focus state based on the images detected at the two focus state detecting elements. The beamsplitter may deflect equal amounts of light to the two light receiving surfaces, and the autofocus adapter may include an iris.

Autofocus adaptor

In a color separation optical system in a camera, subject light entering focus-imaging elements, to which optical path lengths from the taking lens are different, is obtained with a light dividing face. The focusing state is determined with focus evaluation values according to high frequency components of images captured by the focus-imaging elements. Thus, the focusing state can be quickly determined by a simple construction without using the wobbling method. The green light in the subject light entering the color separation optical system is transmitted through a blue light separation prism and a red light separation prism, and is divided into a reflected light and a transmitted light by a beam splitter face, which is a contact face between a first green light separation prism and a second green light separation prism. The light reflected on the beam splitter face exits from the color separation optical system as the subject light for determining the focusing state, and enters the focus-imaging element.

Focusing state determining apparatus

An auxiliary imaging lens is attachable to the main part of zoom lens on the object side; and is configured such that, when capturing an image for a screen having an aspect ratio of 4:3, an effective imaging area having such a size that the screen having an aspect ratio of 4:3 in a case without using the auxiliary imaging lens is just held therein can be secured, and a focal length yielding a field of view area substantially on a par with a field of view area obtained when capturing an image for a screen having an aspect ratio of 16:9 can be set.

Auxiliary imaging lens and imaging apparatus using the same

In a TV camera main body, a still-image-luminous-flux-decomposing prism is disposed adjacent to a color-decomposing prism of a TV-image-capturing system, whereby still images whose aberration is favorably corrected as with TV images are obtained in a simple and compact configuration. A mechanical shutter is disposed in an optical path of the still-image-capturing system, so as to prevent image blurring and smear from occurring due to temporal shifts between field images. A four-block color-decomposing prism A, in which each glass prism has a form identical to a color-decomposing prism of a dual green type, is constituted by a still-image-capturing prism , and a TV-image-capturing three-color-decomposing prism system comprising a prism for blue , a prism for red , and a prism for green . A mechanical shutter is disposed between the light exit end face of the still-image-capturing prism and its cover glass

Optical system for TV camera with still-taking function

In a still-image-capturing system, a still-image-capturing lens group having totally the same configuration (the same number of lens sheets, lens form, and lens material) as the lens group used only for a TV-image-capturing system is disposed downstream a half mirror, and a rectangular prism is disposed for providing a luminous flux with an optical path length identical to that within a color-decomposing prism when the luminous flux passes therethrough. In another aspect, a focal length conversion lens group for changing the focal length of zoom lens groups and a total reflection mirror is disposed on the optical axis of the zoom lens groups exclusively from each other. In still another aspect, an electronic still camera is attached to the still-image-capturing system. If the size of each of image-capturing devices in the TV-image-capturing system is the same as that of the image-capturing device of the electronic still camera, letting the focal length of the fifth lens group be f,, the focal length of the taking lens of the electronic still camera be f,, and the converter magnification of the converter lens be M,, the converter lens satisfying the expression of f,&equals;M,&middot;f,can make the angles of views of the TV-image-capturing and still-image-capturing systems coincide with each other. In still another aspect, a mechanical shutter is disposed between the half mirror and the still-image-capturing lens group, such as to be opened only during the charge storage period of the first field in response to an image readout operation for one frame.

TV lens with still-taking function

An extender lens group removably incorporated in a zoom lens equipped with a temperature compensating feature for increasing the prim-lens focal length to achieve increased magnification is comprised of a front extender lens sub-group including four lens elements and a rear extender lens sub-group including two lens elements, the front extender lens sub-group including two positive bi-convex lens elements each of which has a strong curvature at the subject side surface followed by an overall positive doublet comprising a positive bi-convex lens element with a strong curvature at the subject side surface and a negative bi-concave lens element with a strong curvature at the image side surface and the rear extender lens sub-group including an overall positive doublet comprising a bi-concave lens element with a strong curvature at the image side surface and a positive meniscus lens element with a concave surface on the subject side. The extender lens group satisfying the following conditions: ##EQU1## where P1 is the temperature coefficient of refraction index of the negative lens element in the front extender lens sub-group and P2 is the temperature coefficient of refraction index of the positive lens element in the rear extender lens sub-group, the P1 and P2 being defined by dn/dt relative (.times.10.sup.-6 /.degree.C.) for a wave length of e-line.

Athermalized focal length extender for a zoom lens having a split rear

A zoom lens having four lens groups, the lens groups having refractive power, in order from the object side, of: fixed positive, variable negative, variable positive or negative, and fixed positive. The first lens group from the object side is composed of three lens subgroups, the middle subgroup of which is moved to perform focusing. The second lens group is moved to vary the amount of zoom, and the third lens group moves when the amount of zoom is varied in order to correct for movement of the image plane resulting when the second lens group is moved. Thus, the optical performance of the zoom lens is favorably maintained over the entire image plane. Further, by satisfying certain conditional equations a system that is compact and can focus objects at very near distances is obtained.

Zoom lens of the inner focusing type

A color separation prism having four blocks which can be directly placed at a position, where a color separation prism is to be provided, within a currently-used camera by making the F-number of the color separation prism substantially equivalent to that of an image pick-up lens, and which can implement a dual green system while obtaining the same brightness for the overall optical system as it is obtained from a color separation prism having three blocks. The color separation prism is made up of two prism blocks for separating an incident ray into a green color, one prism block for separating the incident ray into a red color, one prism block for separating the incident ray into a blue color, and an F-number which is substantially the same as an F-number of an image pick-up lens used together with the color separation prism.

Color separation prism

A color separation optical system consisting of prism blocks is provided with a bias light source and a bias light guide-in device. The bias light guide-in device consists of a plane parallel plate located with an air gap in front of an entrance face of the color separation optical system. The plane parallel plate has light reflecting surfaces to reflect the bias light toward the entrance face. The light reflecting surfaces are provided at the periphery of the plane parallel plate and are desirably made into light diffusing faces.

Color separation optical system for color television camera

An optical system for a color television camera includes an interchangeable taking lens, a color separating prism block located behind the taking lens and three image pick-up tubes for different color images located behind the prism block. Between the prism block and at least one of the pick-up tubes an optical element which is capable of varying the optical path length is inserted. The optical path length varying element may be a plane parallel plate or a combination of two optical wedges having parallel opposite end faces. The plane parallel plate changes the optical path length by its thickness. The combination of the two optical wedges varies the optical path length by sliding the wedges with respect to each other to vary the distance between the opposite end faces.

Optical system for color television cameras

A zoom lens system of a color television camera is divided into a front lens component comprising a zooming lens system and a front part of a relay lens system, and three equivalent rear lens components each comprising a rear part of the relay lens system. A color separating prism system is located between the front and the rear parts of the relay lens system. The rear lens components are convergent so that the angle of light beams incident into the prism system may be smaller than that of the light beam incident into the image pick-up tubes.

Growing community of inventors

Omiya, Japan

Kazuo Yoshikawa