Abstract: The zoom lens system and camera using the same include, in order from an object side, a first lens group having negative refracting power and a second lens group having positive refracting power. Zooming is carried out at least by changing the distance between the first and second groups. The first lens group includes six lenses, a first lens which is negative meniscus lens having a concave surface toward an image side, a second lens which is negative meniscus lens having a concave surface toward the image side, a third lens which is negative lens having a concave surface toward the image side, a fourth lens which is positive lens having convex surfaces, a fifth lens having negative power and a sixth lens having positive power. The second lens group includes six lenses and the following condition is satisfied. 0.07<d12/f2G<0.30 where d12 is an air space on an optical axis between the first lens and the second lens in the second lens group, and f2G is a focal length of the second lens group.

Abstract: The zoom lens system and camera using the same include, in order from an object side, a first lens group having negative refracting power and a second lens group having positive refracting power. Zooming is carried out at least by changing the distance between the first and second groups. The first lens group includes six lenses, a first lens which is negative meniscus lens having a concave surface toward an image side, a second lens which is negative meniscus lens having a concave surface toward the image side, a third lens which is negative lens having a concave surface toward the image side, a fourth lens which is positive lens having convex surfaces, a fifth lens having negative power and a sixth lens having positive power. The second lens group includes six lenses and the following condition is satisfied. 0.07<d12/f2G<0.30 where d12 is an air space on an optical axis between the first lens and the second lens in the second lens group, and f2G is a focal length of the second lens group.

Abstract: A diaphragm is clamped between a solenoid unit disposed in a casing and a second valve body in which hydrogen is introduced. A filter comprising a bottomed cylindrical mesh member is mounted in a first passage defined in the first valve body. A restriction having an orifice for restricting the flow rate of hydrogen supplied to first and second communication chambers is mounted in a first port that is disposed upstream of the filter. The restriction and the filter are disposed coaxially in line with each other.

Abstract: 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.

Abstract: A zoom lens system includes a first to a third lens groups. Upon zooming, the distance between the first and second lens groups increases, the distance between the second and third lens groups decreases. Each lens group is positioned closest to the object at the long focal length extremity. The third lens group includes first and second sub-lens groups. The first sub-lens group with at least one aspherical surface is positioned at the object-side end a reference distance, and the negative second sub-lens group is positioned at the image-side end thereof. The zoom lens system satisfies the following conditions: 1.7<fw/f3<2.5 . . . (1); −0.5<fw/f3b<−0.2 . . . (2); −45<&Dgr;Iasp<−20 . . .

Abstract: 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)1/2/f1<0.95 . . . (1); −7.0<(fw*ft)1/2/f2<−4.8 . . . (2); 0.80<X4/X5<0.95 . . .

Abstract: A zoom lens system includes a first to a third lens groups. Upon zooming, the distance between the first and second lens groups increases, the distance between the second and third lens groups decreases. Each lens group is positioned closest to the object at the long focal length extremity. The third lens group includes first and second sub-lens groups. The first sub-lens group with at least one aspherical surface is positioned at the object-side end a reference distance, and the negative second sub-lens group is positioned at the image-side end thereof. The zoom lens system satisfies the following conditions: 1.7<fw/f3<2.5 . . . (1); −0.5<fw/f3b<−0.2 . . . (2); −45<&Dgr;Iasp<−20 . . .

Abstract: 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.

Abstract: 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)½/f1<0.95 . . . (1); −7.0<(fw*ft)½/f2<−4.8 . . . (2); 0.80<X4/X5<0.95 . . .

Abstract: 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/f1<1.80 . . . (1); 1.30<|f/f2|<1.85 . . . (2); 0.48<f/f3<0.75 . . . (3) and 0.10<|L2/f2|<0.22 . . . (4); wherein f designates the focal length of the entire telephoto lens system; f1 designates the focal length of the first lens group; f2 designates the focal length of the second lens group; f3 designates the focal length of the third lens group; and L2 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.

Abstract: 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.

Abstract: A zoom lens system includes a first lens group, a second lens group, and a third lens group. At least the first and third lens groups move along the optical axis for zooming. The second lens group includes at least one negative lens element, and the zoom lens system satisfies the following conditions: 0.65<fw/f1<0.80  (1) 1.73<N2n<1.85  (2) 0.15<X3/fw<0.21  (3) −0.05<X2/X1<0.10  (4) wherein fw designates the focal length of the entire zoom lens system; f1 designates the focal length of the first lens group; N2n designates the average refractive index of the negative lens elements in the second lens group; X3 designates the traveling distance of the third lens group; X2 designates the traveling distance of the second lens group; X1 designates the traveling distance of the first lens group.

Abstract: 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.

Abstract: 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.

Abstract: A telephoto lens system includes a positive first lens group, a negative second lens group and a positive third lens group.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: An eyepiece optical system, which is used in a single lens reflex camera having a penta mirror, includes a negative first single lens element, a positive second single lens element, and a negative third single lens element, in this order from the penta mirror; wherein the second single lens element is a diopter adjusting lens element which is adjustable along the optical axis; and the following conditions are satisfied: −2<f1/fe<0  (1) 0.2<f2/fe<0.5  (2) −10<f3/fe<−1  (3) wherein f1 designates the focal length of the first single lens elements; f2 designates the focal length of the second single lens element; f3 designates the focal length of the third single lens element; and fe designates the focal length of the entire eyepiece optical system when the diopter is −1.0.

Abstract: A zoom lens system includes a first lens group, a second lens group, and a third lens group. At least the first and third lens groups move along the optical axis for zooming.