Abstract: The present invention pertains to: a vanadium pentoxide-tungsten trioxide catalyst supported on an iron ion-exchanged titanium dioxide; and a method for removing nitrogen oxides using the same. More specifically, the present invention pertains to: a deNOxing catalyst in which the iron ion-exchanged titanium dioxide is utilized as a support for the vanadium pentoxide and tungsten trioxide to drastically reduce the generation and emission of nitrous oxide; and a method for removing nitrogen oxides using the same.

Abstract: A wide-angle variable magnification viewfinder comprises from an object side: an objective lens group of a positive refractive power, including a fixed first lens unit of a negative refractive power, a movable second lens unit of a negative refractive power for compensating the change of a view angle, a movable third lens unit of a positive refractive power for changing the magnification of the optical system, a prism for erecting an image, a fixed fourth lens unit of a positive refractive power; and an eyepiece lens group of a positive refractive power; wherein the objective lens group forms an actual image of an object and the actual image can be observed through the eyepiece lens group; and wherein -1.20<L.sub.t /f.sub.1 <-0.75, 0.04<m2w.times.m2.sub.t <0.13; where f.sub.1 represents a focal length of the first lens unit of the objective lens group, L.sub.

Abstract: A super wide-angle variable magnification viewfinder includes an objective lens group of a positive refractive power. The objective lens group further includes a fixed first lens unit of a negative refractive power, a movable second lens unit of a negative refractive power for compensating the change of a view angle, a movable third lens unit of a positive refractive power for changing the magnification of the optical system, and a fixed fourth lens unit of a positive refractive power. Also included in the finder is a prism for erecting an image and an eyepiece lens group of a positive refractive power. The objective lens group forms an actual image of an object, and the actual image can be observed through the eyepiece lens group. The view finder satisfies the condition:1.75<L.sub.t /f.sub.T <1.87where f.sub.T is the focal length of the objective lens group at the telephoto position, and L.sub.t is the distance from a first lens surface of the objective lens group to a focus.

Abstract: A wide-angle zoom lens system includes a first lens group having a positive refractive power and a second lens group having a negative refractive power and spaced from the first lens group at a first distance, the first distance being variable during zooming. The first lens group includes a first lens having a positive refractive power and a convex surface toward an object, a second lens having a negative refractive power and concave surfaces, a third lens having a positive refractive power and convex surfaces, a fourth lens having a negative refractive power and convex surfaces, a fifth lens having a negative refractive power and a concave surface toward the object, and a sixth lens having a positive refractive power and one of convex and meniscus surfaces. The second lens group includes a seventh lens having a positive refractive power and a concave surface toward the object and at least one element of a negative refractive power lens. The zoom lens system having the following characteristics:0.5<f.sub.