Minolta Camera Kabushiki Kaisha

Minolta Camera Co., Ltd.

Akiyoshi Nakamura

Nobuyuki Taniguchi

Takanobu Omaki

Shuzo Matsushita

Toshinobu Ogura

Norio Ishikawa

Takeshi Egawa

Hisashi Tokumaru

Shuji Ogino

Tohru Matsui

Makoto Ando

Yukio Okano

Masato Ishida

Tetsuya Arimoto

Masahide Tanaka

An auto-focusing system includes a focus condition detector which detects focus condition based on the infrared light. A data producer is provided for producing a deflection signal indicating a difference between an image forming distance for the infrared light and that for the visible light, due to aberration. In accordance with the detected focus condition and deflection signal, an objective lens is shifted to a position for properly focusing an image of visible light on an image forming plane.

Auto-focusing system for cameras with in interchangeable objective lens

In an interchangeable lens including an optical system adjustable for focusing and adapted to be detachably mounted on a camera body which is provided with focus detection means for detecting an amount of defocus of an object image formed by the optical system, and drive means for driving the optical system for the focus adjustment thereof in accordance with the detected amount of defocus. The interchangeable lens comprises, inter alia, a code plate for producing a plurality of digital photographic distance signals representing given discrete photographic distances of the optical system in accordance with the adjustment of the optical system for focusing. Circuit means output a predetermined one of a plurality of inputs, the plurality of outputs including a plurality of conversion coefficients needed for converting the detected amount of defocus into the amount of drive to be effected by the driving means, the conversion coefficients being intrinsic to the interchangeable lens and having values depending upon the discrete photographic distances of the optical system represented by the digital photographic distance signals, respectively. The digital photographic distance signals are applied to the circuit means as the predetermined input to cause the circuit means to output one of the conversion coefficients as the predetermined output, the value of which depends upon the photographic distance of the optical system represented by the one digital photographic distance signal being produced. The output conversion coefficient are transmitted to the camera body.

Data input/output device for a camera

An automatic focusing device which compises a defocus amount detecting unit for detecting a defocus amount attributable to a first optical system of an interchangeable lens assembly and a second optical system of an AF convertor, a converting circuit for converting the defocus amount into a data corresponding to a focusing amount of the second optical system which varies in non-linear relationship to the defocus amount, and an optical drive unit for moving the second optical system on the basis of a data representative of the focusing amount supplied from the converting circuit.

Automatic focusing device and automatic exposure control device

An improvement of an inverted telephoto type wide angle lens system having, from the object to the image side a front lens group of a negative refractive power which is left stationary upon focusing, and a rear lens group of a positive refractive power which is shiftable for the purpose of focusing is disclosed. The improvement is characterized in that the lens system fulfills the following condition:

Inverted telephoto type wide angle lens system with a rear focusing unit

An automatic focusing device which comprises a defocus amount detecting unit for detecting a defocus amount attributable to a first optical system of an interchangeable lens assembly and a second optical system of an AF convertor, a converting circuit for converting the defocus amount into a data corresponding to a focusing amount of the second optical system which varies in non-linear relationship to the defocus amount, and an optical drive unit for moving the second optical system on the basis of a data representative of the focusing amount supplied from the converting circuit.

A telephoto lens system comprises, from the object side to the image side, a first positive lens unit, a second negative lens unit, and a third positive lens unit, the second lens unit alone being shiftable along the optical axis with the first and third lens units being stationary for focusing the whole lens system. The first lens unit consists of a first positive component, a second positive meniscus component convex to the object side, and a third negative component of a doublet composed of cementing together a positive meniscus lens convex to the object side and a negative meniscus lens convex to the object side, the cemented surface of the third component being convex to the object side. Another feature is characterized that the light pencils exited from the second lens unit are properly convergent.

Telephoto lens system

An auto-focusing system includes a focus condition detector which detects the focus condition based on infrared light. A data producer is provided for producing a deflection signal indicating the difference between an image forming distance for infrared light and that for visible light, due to aberration. In accordance with the detected focus condition and deflection signal, an objective lens is shifted to a position for properly focusing an image of visible light on an image forming plane.

Auto-focusing system

An active focus detecting device for use in a camera is provided and includes emitting light that is polarized, and collimated so that the light forms a light bundle which will pass near the optical axis of the objective lens, and then will be projected in a diverging light path after having been focused by the objective lens towards the object. A polarization component is provided for receiving the returning light and directing a component of that light towards a detector for determining a focusing condition.

Focus detection device

An inverted telephoto type wide angle lens system is provided. The lens system comprises an aperture stop, a first lens group located at the object side of the aperture stop, and a second lens group located at the image side of the aperture stop, the second lens group including at least two movable focusing lens groups, whereby the focusing is practiced by only the movement of the focusing lens groups with the remaining lens elements in the lens system stationary.

Inverted telephoto type wide angle lens system

An improved wide angle zoom lens system of an inverted telephoto type having a negative object side lens group and a positive image side lens group is provided, in which an air space to be varied in accordance with the shift of the object side lens group for focusing is located at the image side of a negative component in the object side lens group.

Zoom lens system

The present invention is directed to an inverted telephoto type wide angle lens system having a field angle of 114 degrees and an aperture ratio of 1/2.8. The lens system comprises eleven lens groups and fourteen lens elements which fulfill the following conditons:

An inverted telephoto type wide angle lens system of an aperture ratio, 1/2.0 and a field angle, 84 degrees is provided. The lens system consists, from the object to the image side, of: a first component of a positive meniscus lens element convex to the object side; a second component of a negative meniscus lens element convex to the object side; a third component of a negative meniscus lens element convex to the object side; a fourth component of a biconvex lens element; an aperture stop; a fifth component of a positive meniscus lens element convex to the object side; a sixth component of a biconvex lens element; a seventh component of a biconcave lens element; an eighth component of a positive meniscus lens element convex to the image side; and a ninth component of overall positive refractive power including at least one lens element. The sixth component can be axially moved relative to the other components in association with the focusing for correcting the aberrations which would occur upon close focusing.

The present invention is directed to a compact lens system equally operable in both air and water, comprising a first lens group having a front surface directly facing the air or water medium, the center of the curvature of the front surface being located approximately at the entrance pupil of the lens system, and a second lens group located at the image side of the first lens group with an air space formed between the first and second lens groups. The air space and design parameters being selected in the lens system so that the field curvature of the lens system is mainly changed without any substantial change in other aberrations when the air space is changed, wherein the air space is changeable by a predetermined value in response to the change between use in air and use under water for maintaining a relatively flat image surface.

Compact lens system operable in different mediums

The present invention is directed to an inverted telephoto type wide angle lens system having eight lens groups and eight lens elements which fulfill the following conditions:

Lightweight inverted telephoto type wide angle lens system

The inverted telephoto type wide angle lens system of the present invention includes, from the object to image side, a first lens group having a positive single lens, a first negative meniscus single lens convex to the object side and a second negative meniscus single lens convex to the object side. A second lens group includes at least one positive lens while a third lens group includes, from the object to the image side, a first positive meniscus single lens convex to the image side, a biconcave single lens, a second positive single lens convex to the image side and a positive single lens. In addition, the inverted telephoto type wide angle lens system of the present invention fulfills the following conditions:

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Sakai, Japan

Akiyoshi Nakamura