Abstract: A projection zoom lens includes, from a screen side to an image source side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power. Zooming the projection zoom lens from the wide-angle end to the telephoto end causes the second, third and fourth lens groups to move toward the screen side, and the first and fifth lens groups are kept stationary. The projection zoom lens may further include an auto iris being axially movable with the fourth lens group, a composite prism and a cover glass. The projection zoom lens satisfies several conditions so that it can effectively eliminate aberrations and improve the projection image quality.

Abstract: A compact zoom lens includes a first lens group (1, 3) of negative refractive power disposed on an object side and a second lens group (2, 4) of positive refractive power disposed on an image side. Both the first and second lens groups are movable. The first and second lens groups defines a variable distance therebetween. During zooming from the wide-angle end to the telephoto end, the second lens group moves toward the object side and the variable distance between the first and second lens groups decreases. The compact zoom lens has a long back focal length with various aberrations satisfactorily corrected.

Abstract: A projection zoom lens includes, from a screen side to an image source side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a positive refractive power, a fourth lens group having a negative refractive power and a fifth lens group having a positive refractive power. Zooming the projection zoom lens from the wide-angle end to the telephoto end causes the second, third and fourth lens groups to move toward the screen side, and the first and fifth lens groups are kept stationary. The projection zoom lens may further include an auto iris being axially movable with the fourth lens group, a composite prism and a cover glass. The projection zoom lens satisfies several conditions so that it can effectively eliminate aberrations and improve the projection image quality.

Abstract: A compact zoom lens includes, in order from an object side to an image side, a first lens group (1) of negative refractive power, and second, third, fourth and fifth lens groups (2, 3, 4, 5) of positive refractive power. The second, third and fourth lens groups are movable to effect zooming and focusing. During zooming from the telephoto end to the wide-angle end, the fourth lens group moves from the object side to the image side. The compact zoom lens has a long back focal length with various aberrations satisfactorily corrected, and a small F-number for enhanced image brightness.

Abstract: A compact zoom lens includes, in order from an object side to an image side, a first lens group (1) of negative refractive power, and second, third, fourth and fifth lens groups (2, 3, 4, 5) of positive refractive power. The second, third and fourth lens groups are movable to effect zooming and focusing. During zooming from the telephoto end to the wide-angle end, the fourth lens group moves from the object side to the image side. The compact zoom lens has a long back focal length with various aberrations satisfactorily corrected, and a small F-number for enhanced image brightness.

Abstract: A compact zoom lens includes a first lens group (1, 3) of negative refractive power disposed on an object side and a second lens group (2, 4) of positive refractive power disposed on an image side. Both the first and second lens groups are movable. The first lens group and the object side defines a first variable distance therebetween, and the first and second lens groups defines a second variable distance therebetween. During zooming from the telephoto end to the wide-angle end, the second lens group moves toward the image side and the second variable distance decreases. The compact zoom lens has a long back focal length with various aberrations satisfactorily corrected.

Abstract: A projection zoom lens includes, from an image side to an object side, a first lens group having a negative refractive power, consisting of a number of lens elements and being movable along the optical axis of the projection zoom lens; a second lens group having a positive refractive power, consisting of a number of lens elements and being movable along the optical axis of the projection zoom lens; and an aperture stop arranged between two lens elements of the second lens group and being axially movable therewith.