Pentax Corporation

Asahi Kogaku Kogyo Kabushiki Kaisha

Asahi Kogaku Kabushiki Kaisha

Masayuki Murata

Takayuki Ito

Isamu Hirai

Masami Shirai

Zoom lens system

An AF auxiliary light projector for an AF camera includes a focus detection optical system having a first optical axis, and an AF auxiliary light projecting optical system having a second optical axis which intersects the first optical axis, the AF auxiliary light projecting optical system projecting an image having a predetermined contrast pattern onto an object. The AF auxiliary light projecting optical system includes a projector lens, a contrast pattern chart, an illumination lens, and an illumination light source, in that order. The illumination lens has an asymmetrical optical power so that an optical power of a far distance portion of the illumination lens for a far distance region of the contrast pattern chart is greater than an optical power of a near distance portion of the illumination lens for a near distance region of the contrast pattern chart.

AF auxiliary light projector for AF camera

A surveying instrument having a sighting optical system and a phase-difference detection type focus detection device which detects a focus state of the sighting optical system from a correlation between a pair of images respectively formed by two light bundles which are respectively passed through two different pupil areas on an objective lens of the sighting optical system, the phase-difference detection type focus detection device includes a pair of line sensors, a condenser lens group for condensing the two light bundles which are respectively passed through the two different pupil areas, and a pair of separator lens groups for forming two images of the two light bundles which are passed through the condenser lens group on the pair of line sensors, respectively. The condenser lens group includes more than one sub lens group.

Surveying instrument having a sighting telescope and a phase-difference detection type focus detection device therefor

A wide-angle lens system includes a negative first lens group, and a positive second lens group. The first lens group includes a positive lens element, and a negative lens element. The wide-angle lens system satisfies the following conditions: 0<(&phgr; &plus;&phgr; )/&phgr;<0.3 . . . (1); 0.5<HF/HL<0.9 . . . (2); &phgr; &equals;(1&minus;n )/r ;&phgr; &equals;(n &minus;1)/r ; &phgr;&equals;1/f; n : the refractive index of the positive lens element of the first lens group; n : the refractive index of the most object-side negative lens element of the first lens group;r : the radius of curvature of the image-side surface of the positive lens element of the first lens group; r : the radius of curvature of the object-side surface of the most object-side negative lens element of the first lens group; f: the focal length of the entire lens system; HF: the radius of a bundle of axial light rays with respect to the most object-side surface of the first lens group; and HL: the radius of a bundle of axial light rays with respect to the most object-side surface of the second lens group.

Wide-angle lens system

Wide-angle lens system and a focusing method thereof

A macro zoom lens system includes at least three lens groups, such as, a positive first lens group, a negative second lens group, and a positive third lens group, in this order from the object. Upon zooming, at least two lens groups are made moveable. On the other hand, upon focusing at any focal length in the focal-length range defined by the short focal length extremity and the long focal length extremity, any one of the lens groups other than the first lens group is made moveable. Furthermore, at the shortest object-to-image distance, an image magnification of more than &frac12; is obtained at the long focal length extremity.

Macro zoom lens system

Soft focus lens systems

A macro lens system includes a positive first lens group, an aperture and a negative second lens group arranged in the order from an object side. The driving mechanism drives the lens groups and the aperture to move independently along an optical axis for focusing. When the lens groups are moved toward the object side, the aperture is also moved to the object side. The moving amount of the aperture is determined to control increasing of an effective F-number. The moving amount of the aperture is smaller than that of the first lens group and is larger than that of the second lens group.

Macro lens system

A macro lens system includes a positive first lens group, an aperture and a negative second lens group arranged in the order from an object side. The lens groups are driven to move along an optical axis for focusing. When the lens groups are driven, a full-opening diameter of the aperture is changed such when the lens groups is moved toward the object side to focus on a closer object, the full-opening diameter is increased.

A soft-focus zoom lens system comprises a negative front lens group and a positive rear lens group, both of which are arranged to perform a zooming operation by moving the first lens group and the second lens group, by varying the distance between the negative front lens group and the positive rear lens group, wherein the soft-focus zoom lens system satisfies the following conditions:

Growing community of inventors

Saitama, Japan

Masayuki Murata