Asahi Kogaku Kogyo Kabushiki Kaisha

Pentax Corporation

Hiroyasu Ozaki

Takayuki Ito

Kazunori Takahashi

Shigeru Morishita

Sachio Hasushita

Takuji Hamasaki

Hiroshi Kurei

Tadayuki Kirigaya

Kaoru Imakyure

Zoom lens system

A zoom lens system includes a positive first lens group, a negative second lens group, and a positive third lens group, in this order from the object. Upon zooming from the short focal length extremity to the long focal length extremity, the positive first lens group remains stationary, the negative second lens group moves toward the image, and the positive third lens group moves toward the object. The positive first lens group includes a first sub-lens group which is stationary and a second sub-lens group which functions as a focusing lens group.

A high-magnification zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, a negative fourth lens group, and a positive fifth lens group. Upon zooming from the short focal length extremity to the long focal length extremity, at least the positive first lens group, the positive third lens group, the negative fourth lens group, and the positive fifth lens group move from the image side toward the object side. The high-magnification zoom lens system satisfies the following conditions: 0.65<(fw*ft) /f1<0.95 . . . (1); &minus;7.0<(fw*ft) /f2<&minus;4.8 . . . (2); 0.80<X4/X5<0.95 . . . (3); wherein fw: the focal length of the entire high-magnification zoom lens system at the short focal length extremity; ft: the focal length of the entire high-magnification zoom lens system at the long focal length extremity; f1:the focal length of the positive first lens group; f2: the focal length of the negative second lens group; X4:the traveling distance of the negative fourth lens group upon zooming from the short focal length extremity to the long focal length extremity; and X5:the traveling distance of the positive fifth lens group upon zooming from the short focal length extremity to the long focal length extremity.

High-magnification zoom lens system

A telephoto lens system includes a positive first lens group, a negative second lens group and a positive third lens group. Upon focusing, the second lens group moves toward the image, and the telephoto lens system satisfies the following conditions: 1.35<f/f <1.80 . . . (1); 1.30<&verbar;f/f &verbar;<1.85 . . . (2); 0.48<f/f <0.75 . . . (3) and 0.10<&verbar;L f &verbar;<0.22 . . . (4); wherein f designates the focal length of the entire telephoto lens system; f designates the focal length of the first lens group; f designates the focal length of the second lens group; f designates the focal length of the third lens group; and L designates the distance between the second lens group and the third lens group when an object at an infinite photographing distance is in an in-focus state.

Telephoto lens system

A zoom lens system includes a positive first lens group, a negative second lens group, a positive third lens group, and a positive fourth lens group. Upon zooming from the short focal length extremity to the long focal length extremity, at least the first, second and third lens groups are moved so that the distance between the first and the second lens groups increases, the distance between the second and the third lens groups decreases, and the distance between the third and the fourth lens groups increases.

A zoom lens system includes at least three lens groups, in which the distance between at least two lens groups of the at least three lens groups is varied during zooming, the zoom lens system having a first adjustment mechanism for mechanically adjusting a first lens group in the optical axis direction upon assembly and adjustment; a second adjustment mechanism for mechanically adjusting a second lens group, which is different from the first lens group, in the optical axis direction upon assembly and adjustment; and a third adjustment mechanism for mechanically adjusting a third lens group, which is different from the first and second lens group, in the optical axis direction upon assembly and adjustment.

Zoom lens system and adjusting method of same

A zoom lens system includes a plurality of lens groups, wherein a deflector which deflects the optical axis of said zoom lens system is positioned between lens groups which are made moveable upon zooming.

A viewfinder optical system of a single-lens reflex camera has a photographic optical system and an image plane positioned on an optical axis of the photographic optical system. The system includes a first optical member positioned between the photographic optical system and the image plane, the first optical member bending the optical axis of the photographic optical system to define a viewfinder optical axis of the viewfinder optical system. A second optical member bends the viewfinder optical axis at least once to make the viewfinder optical axis that extends parallel to the optical axis of the photographic optical system. A third optical member, having substantially no optical power, is positioned on the viewfinder optical axis extending parallel to the optical axis of the photographic optical system. The third optical member is made of a transparent material having a refractive index higher than the refractive index of air. An eyepiece is positioned behind the third optical member on the viewfinder optical axis.

Viewfinder optical system of a single-lens reflex camera

A step zoom lens includes a first movable lens group of negative power, a diaphragm which is immovable during zooming, and a second lens group of positive power. A fundamental zooming path along which the first lens group is moved to vary a focal length without causing an image shift is defined so that the distance of the first lens group from the diaphragm is reduced and is thereafter increased, upon zooming from a wide angle extremity to a telephoto extremity, and a fundamental zooming path along which the second lens group is moved is defined so that the distance of the second lens group from the diaphragm is linearly varied. The discrete stop positions of the first and second lens groups are determined to be different from a focal length position at which the distance between the first lens group and the diaphragm on the fundamental zooming path thereof is minimum or the vicinity thereof.

Step zoom lens

Eyepiece optical system for a single lens reflex camera

A telephoto zoom lens includes a first positive lens group, a second negative lens group, a third positive lens group and a fourth lens group. A resultant refractive power of the third and fourth lens groups are moved from an image side to an object side upon zooming from a short focal length extremity to a long focal length extremity, so that a distance between the first and second lens groups increases, a distance between the second and third lens groups decreases, and a distance between the third and fourth lens groups becomes smallest at an intermediate focal length. The zoom lens satisfies a condition specified by (0.1&lt;X.sub.3 /X.sub.1 &lt;0.5), wherein X.sub.1 represents a distance between a position at the short focal length extremity and at the long focal length extremity of the first lens group on an optical axis, and X.sub.3 represents a distance between the positions at the short focal length extremity and at the long focal length extremity of the third lens group on the optical axis, respectively.

Telephoto zoom lens

A photographic lens system composed of a negative first lens group, a diaphragm, and a positive second lens group, in this order from the object side. The second lens group has a positive meniscus lens element having a convex surface facing the image side, a cemented sub-lens group having a positive lens element and a negative lens element, and a positive single lens element, in this order from the object side, wherein the photographic lens system satisfies the following conditions:

Lens system for electronic photography

A data printing device is provided which comprises a light emitting device that includes a plurality of light emitting elements, and an imaging optical system for forming light spots corresponding to the light emitting elements on the film. Preferably, the imaging optical system satisfies the following condition: 0.6&lt;.vertline.m.vertline.&lt;1.5, where 'm' represents the magnification of the imaging optical system. The light emitting device comprises a light emitting diode in which a plurality of light emitting elements are included on a single substrate. The plurality of light emitting elements are aligned along a straight line perpendicular to a direction of film winding. The imaging optical system includes of a single imaging lens or a plurality of lenses.

Growing community of inventors

Tokyo, Japan

Hiroyasu Ozaki