Abstract: A projection lens system is constructed as a zoom lens system which is for use with a laser light source and performs magnification variation by moving at least a lens group along the optical axis, and the projection lens system fulfills the following conditional formula: (|AC(B2?G)|+|AC(R2?G)|)/(|AC(B1?G)|+|AC(R1?G)|)<0.8, where AC(B2?G) represents longitudinal chromatic aberration between the wavelengths ?B2 and ?G; AC(R2?G) represents longitudinal chromatic aberration between the wavelengths ?R2 and ?G; AC(B1?G) represents longitudinal chromatic aberration between the wavelengths ?B1 and ?G; and AC(R1?G) represents longitudinal chromatic aberration between the wavelengths ?R1 and ?G.

Abstract: An object of the invention is to provide a projection lens capable of sufficiently correcting lateral chromatic aberration at both of the wide-angle end and the telephoto end, with an increased zoom ratio, a less number of lens elements, and less variation in telecentricity.

Abstract: An object of the invention is to provide a projection lens capable of sufficiently correcting lateral chromatic aberration at both of the wide-angle end and the telephoto end, with an increased zoom ratio, a less number of lens elements, and less variation in telecentricity.

Abstract: A projection lens system 1A enlarges and projects onto a screen 8, via a plurality of lenses G1 to G16, image light emitted from, a light source 4 and modulated by DMDs 3r to 3b. A movable lens barrel 25 holds the lens G16, having positive power, which is positioned closest to the DMDs 3r to 3b. An outer tube 24 holds the movable lens barrel 25 to enable movement in the optical axis direction. Through thermal deformation at the time of an increase in temperature, the bimetal member 27 moves the movable lens barrel 25 in the optical axis direction so as to recede from the image formation devices which are the DMDs 3r to 3b.

Abstract: In zooming, an optical unit moves the lens unit located at the most image side and the image sensor along the optical axis while not moving at least one lens unit, of a plurality of lens units, other than the lens unit located at the most image side.

Abstract: In a lens unit including a plurality of lens groups, the first, most object-side lens group includes a prism that changes the optical axis. In this lens unit, during zooming, while the first lens group is kept stationary, an image-sensing device is moved along the optical axis.

Abstract: A variable magnification optical system includes lens units that focus a ray of light from an object side on an image sensor, in which the lens unit located at a first position from the object side toward the image side includes an optical path changing element for changing an optical path. The variable magnification optical system performs magnification variation by changing gaps between the lens units, and satisfies predetermined conditional formulae.

Abstract: A variable-magnification optical system has, from the object side to the image side, at least a first lens group having a positive optical power, a second lens group having a negative optical power, and a third lens group having a positive optical power. The first lens group includes an optical prism that changes the optical path, and a prescribed conditional formula is fulfilled.

Abstract: A variable magnification optical system for forming an optical image of an object on the light receiving surface of the image sensor so that the magnification is variable includes from the object side: a first lens unit GR1 having negative optical power; a second lens unit GR2 having positive optical power; a third lens unit GR3 having positive optical power; and a fourth lens unit GR4 having positive or negative optical power. In magnification variation from the wide-angle end (W) to the telephoto end (T), at least first lens unit GR1 and the second lens unit GR2 are movable, and the fourth lens unit GR4 is stationary. An optical member having a wavelength selecting property is included in the fourth lens unit GR4.

Abstract: An image forming device is provided with: a zoom lens system TL that performs magnification varying by changing the distance between the lens units; and an image sensor SR that converts an optical image formed by the zoom lens system TL into an electric signal. The zoom lens system TL comprises three lens units of negative, positive, positive configuration. The second lens unit Gr2 comprises three single lens elements of, from the object side, a positive lens element L21, a negative meniscus lens element L22 convex to the object side and a positive lens element L23. A condition 1.0<|P22/P21|<2.0 (P21 is the optical power of the object side positive lens element L21 in the second lens unit GR2, and P22 is the optical power of the negative meniscus lens element L22 in the second lens unit GR2) is satisfied.

Abstract: A projection lens system 1A enlarges and projects onto a screen 8, via a plurality of lenses G1 to G16, image light emitted from, a light source 4 and modulated by DMDs 3r to 3b. A movable lens barrel 25 holds the lens G16, having positive power, which is positioned closest to the DMDs 3r to 3b. An outer tube 24 holds the movable lens barrel 25 to enable movement in the optical axis direction. Through thermal deformation at the time of an increase in temperature, the bimetal member 27 moves the movable lens barrel 25 in the optical axis direction so as to recede from the image formation devices which are the DMDs 3r to 3b.

Abstract: A plurality of lens units in an optical unit has at least: from the object side toward the image side, a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. When at least the first lens unit moves from the image side to the object side in zooming from the wide-angle end position to the telephoto end position, at least one gap between the lens units varies. Predetermined conditional formulae are satisfied.

Abstract: An image forming device is provided with: a zoom lens system TL that performs magnification varying by changing the distance between the lens units; and an image sensor SR that converts an optical image formed by the zoom lens system TL into an electric signal. The zoom lens system TL includes at least a negative first lens unit GR1 and a positive second lens unit GR2, and at least the first lens unit GR1 and the second lens unit GR2 move in zooming from the wide angle end (W) to the telephoto end (T). The second lens unit GR2 includes three lens elements of, from the object side, a positive meniscus lens element L21 convex to the object side, a negative lens element L22 and a positive lens element L23, and the following condition is satisfied: ?1.0<(CR1?CR2)/(CR1+CR2)<0.0 (CR1 is the front radius of curvature of the most object side lens element L21 in the second lens unit GR2, and CR2 is the rear radius of curvature of the most object side lens element L21 in the second lens unit GR2).

Abstract: A zoom lens system for forming an optical image of a subject on the image-sensing surface of an image sensor has three lens units, namely, from the object side thereof, a first lens unit having a negative optical power, a second lens unit having a positive optical power, and a third lens unit having a positive optical power. The lens units each include at least one plastic lens element. The zoom lens system as a whole includes at least one glass lens element that fulfills a prescribed conditional formula.

Abstract: A variable magnification optical system includes lens units that focus a ray of light from an object side on an image sensor, in which the lens unit located at a first position from the object side toward the image side includes an optical path changing element for changing an optical path. The variable magnification optical system performs magnification variation by changing gaps between the lens units, and satisfies predetermined conditional formulae.

Abstract: A plurality of lens units in an optical unit has at least: from the object side toward the image side, a first lens unit having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. When at least the first lens unit moves from the image side to the object side in zooming from the wide-angle end position to the telephoto end position, at least one gap between the lens units varies. Predetermined conditional formulae are satisfied.

Abstract: A variable-magnification optical system has, from the object side to the image side, at least a first lens group having a positive optical power, a second lens group having a negative optical power, and a third lens group having a positive optical power. The first lens group includes an optical prism that changes the optical path, and a prescribed conditional formula is fulfilled.

Abstract: In zooming, an optical unit moves the lens unit located at the most image side and the image sensor along the optical axis while not moving at least one lens unit, of a plurality of lens units, other than the lens unit located at the most image side.

Abstract: In a lens unit including a plurality of lens groups, the first, most object-side lens group includes a prism that changes the optical axis. In this lens unit, during zooming, while the first lens group is kept stationary, an image-sensing device is moved along the optical axis.

Abstract: A zoom lens system for forming an optical image of a subject on the image-sensing surface of an image sensor includes at least, from the object side thereof, a first lens unit having a negative optical power and a second lens unit having a positive optical power, and achieves zooming by varying the distances between the individual lens units in such a way that, during zooming from the wide-angle end to the telephoto end, the distance between the first and second lens units decreases. The first lens unit consists of two plastic lens elements.