Abstract: An embodiment of this invention provides a zoom lens that includes, in order from an object side to an image-forming side, a first lens group having positive refraction power; a second lens group having negative refraction power; a third lens group having positive refraction power; and a fourth lens group having positive refraction power; wherein the second lens group and the fourth lens group move along an optical axis for zooming between a wide-angle end and a telephoto end.

Abstract: An embodiment of this invention provides a zoom lens, which primarily comprises, in order from an object side to an image-forming side, a first lens group having negative refractive power; a second lens group having positive refractive power; and a third lens group having positive refractive power. The second lens group includes a plurality lenses in which the refractive index of the lens nearest to the object side is NDo, the refractive index of the lens nearest to the image-forming side is NDi, and NDo and NDi satisfy: NDi?NDo>0.1.

Abstract: An embodiment of this invention provides a zoom lens that primarily comprises, in order from an object side to an image-forming side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. The second lens group comprises several lenses, in which the focal length of the first lens from the object side is efl3, the focal length of the second lens from the object side is efl4, and efl3 and efl4 satisfy: 0<efl3/efl4<0.3.

Abstract: An embodiment of this invention provides a zoom lens, which primarily includes, in order from an object side to an image-forming side, a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; a fifth lens group having negative refractive power; and a sixth lens group having positive refractive power; wherein the first lens group comprises a prism, and the second lens group, the fourth lens group, and the fifth lens group are moved toward the third lens group along an optical axial for zooming from a wide-angle end to a telephoto end.

Abstract: A zoom lens is provided. The zoom lens includes a first lens group, a second lens group and a third lens group. The first lens group includes at least one lens. The second lens group includes at least one lens. The first lens group, the second lens group and the third lens group are arranged in order from an object side to an image side. The zoom lens satisfies following conditions: NdA<1.65, NdB<1.65, and GD2/GD1<1.35. NdA is a refraction index of the first lens group. NdB is a refraction index of the second lens group. GD1 is a thickness of the first lens group along an optical axis. GD2 is a thickness of the second lens group along an optical axis.

Abstract: This invention provides compact photographic and projection modules and electronic systems having the photographic and projection modules, which not only can project image data but also can capture image with good image quality high zoom ratio. Additionally, the photographic and projection modules are reliable and able to be made with low cost.

Abstract: An embodiment of this invention provides a zoom lens that primarily comprises, in order from an object side to an image-forming side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having positive refractive power. The second lens group comprises several lenses, in which the focal length of the first lens from the object side is efl3, the focal length of the second lens from the object side is efl4, and efl3 and efl4 satisfy: 0<efl3/efl4<0.3.

Abstract: A zoom lens is provided. The zoom lens includes a first lens group, a second lens group and a third lens group. The first lens group includes at least one lens. The second lens group includes at least one lens. The first lens group, the second lens group and the third lens group are arranged in order from an object side to an image side. The zoom lens satisfies following conditions: NdA<1.65, NdB<1.65, and GD2/GD1<1.35. NdA is a refraction index of the first lens group. NdB is a refraction index of the second lens group. GD1 is a thickness of the first lens group along an optical axis. GD2 is a thickness of the second lens group along an optical axis.

Abstract: An embodiment of this invention provides a zoom lens, which primarily comprises, in order from an object side to an image-forming side, a first lens group having negative refractive power; a second lens group having positive refractive power; and a third lens group having positive refractive power. The second lens group includes a plurality lenses in which the refractive index of the lens nearest to the object side is NDo, the refractive index of the lens nearest to the image-forming side is NDi, and NDo and NDi satisfy: NDi-NDo>0.1.

Abstract: An embodiment of this invention provides a zoom lens that includes, in order from an object side to an image-forming side, a first lens group having positive refraction power; a second lens group having negative refraction power; a third lens group having positive refraction power; and a fourth lens group having positive refraction power; wherein the second lens group and the fourth lens group move along an optical axis for zooming between a wide-angle end and a telephoto end.

Abstract: An embodiment of this invention provides a zoom lens, which primarily includes, in order from an object side to an image-forming side, a first lens group having positive refractive power; a second lens group having negative refractive power; a third lens group having positive refractive power; a fourth lens group having positive refractive power; a fifth lens group having negative refractive power; and a sixth lens group having positive refractive power; wherein the first lens group comprises a prism, and the second lens group, the fourth lens group, and the fifth lens group are moved toward the third lens group along an optical axial for zooming from a wide-angle end to a telephoto end.

Abstract: An embodiment of this invention provides a zoom lens, which includes, in order from an object side to an image-forming side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, a fourth lens group having positive refractive power, and a fifth lens group having negative refractive power, wherein the second lens group, the fourth lens group, and the fifth lens group are moving with respect to one another, for zooming from a wide-angle end to a telephoto end thereof.

Abstract: This invention provides compact photographic and projection modules and electronic systems having the photographic and projection modules, which not only can project image data but also can capture image with good image quality high zoom ratio. Additionally, the photographic and projection modules are reliable and able to be made with low cost.

Abstract: A wide-angle projection lens and a projection apparatus using the same are provided. The wide-angle projection lens, from an image side of the projection apparatus, includes a first lens group, a second lens group and a third lens group. An aperture stop of the wide-angle projection lens is disposed in the third lens group. The first lens group has a negative effective refractive power and at least one aspheric lens surface. The second lens group has a first positive effective refractive power. The third lens group has a second positive effective refractive power. The effective focal length of the wide-angle projection lens is between 6.5 mm and 9.5 mm.

Abstract: A wide-angle projection lens and a projection apparatus using the same are provided. The wide-angle projection lens, from an image side of the projection apparatus, includes a first lens group, a second lens group and a third lens group. An aperture stop of the wide-angle projection lens is disposed in the third lens group. The first lens group has a negative effective refractive power and at least one aspheric lens surface. The second lens group has a first positive effective refractive power. The third lens group has a second positive effective refractive power. The effective focal length of the wide-angle projection lens is between 6.5 mm and 9.5 mm.