Abstract: A fixed focal length lens including a first lens group, a second lens group, and a third lens group arranged in sequence from a magnified side towards a reduced side is provided. The first lens group has a positive refractive power, and includes a first lens and a second lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the first lens and the second lens are respectively negative and positive. The second lens group has a positive refractive power, and includes a third lens, a fourth lens, and a fifth lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the third lens, the fourth lens, and the fifth lens are respectively positive, negative, and positive. The third lens group has a positive refractive power, and includes a sixth lens. A refractive power of the sixth lens is positive.

Abstract: A zoom lens disposed between an object side and an image side and including a first, second, third, and fourth lens group is provided. The first lens group has a negative refractive power and includes a first lens and a prism arranged in sequence from the object side to the image side. The first lens is an aspheric lens. A distance between the first lens and the prism is L, an effective focal length of the zoom lens at a wide-end is fw, and 1.58<L/fw<1.88. The second lens group disposed between the first lens group and the image side has a positive power and includes a first double cemented lens. The third lens group disposed between the second lens group and the image side has a negative power and includes a second double cemented lens. The fourth lens group has a positive power.

Abstract: A projection lens for projecting an image beam is provided. The image beam is converted by a light valve from an illumination beam irradiating the light valve. The projection lens includes a first lens group, a second lens group, and a third lens group. The first lens group is disposed on a transmission path of the image beam, and has a first optical axis. The second lens group is disposed on both a transmission path of the illumination beam and the transmission path of the image beam, and between the light valve and the first lens group. The second lens group has a second optical axis. The second optical axis is inclined with respect to the first optical axis. The third lens group is disposed on the transmission path of the image beam, and between the first lens group and the second lens group. A projection apparatus is also provided.

Abstract: A zoom lens disposed between an object side and an image side and including a first, second, third, and fourth lens group is provided. The first lens group has a negative refractive power and includes a first lens and a prism arranged in sequence from the object side to the image side. The first lens is an aspheric lens. A distance between the first lens and the prism is L, an effective focal length of the zoom lens at a wide-end is fw, and 1.58<L/fw<1.88. The second lens group disposed between the first lens group and the image side has a positive power and includes a first double cemented lens. The third lens group disposed between the second lens group and the image side has a negative power and includes a second double cemented lens. The fourth lens group has a positive power.

Abstract: A fixed focus lens includes, numbered in order of location from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens. The first lens is a biconvex lens with a positive refractive power, and the second lens is a convex-concave lens with a negative refractive power. The third lens is a concave-convex lens with a positive refractive power, and the fourth lens is an aspherical lens having a negative refractive power in the centre portion thereof and a positive refractive power at the periphery portion thereof. The fixed focus lens satisfies the condition: 1.0>|(1/r2?1/r1)|>0.6, where r1 denotes the radius of curvature of a front surface of the second lens and r2 denotes the radius of curvature of a rear surface of the first lens.

Abstract: A projection lens includes a first lens group with a negative refractive power, a second lens group with a negative refractive power, and a third lens group with a positive refractive power, wherein the second lens group is disposed between the first lens group and the third lens group. The first lens group includes an aspheric lens. The second lens group includes a first lens and a second lens. The third lens group includes a third lens, a forth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens.

Abstract: A fixed-focus lens adapted to be disposed between a magnified side and a reduced side is provided. The fixed-focus lens includes a first lens group, a second lens group, and a third lens group. The first lens group disposed between the magnified side and the reduced side includes three lenses and has a negative refractive power. The second lens group disposed between the first lens group and the reduced side includes five lenses and has a positive refractive power. The third lens group disposed between the second lens group and the reduced side includes five lenses and has a positive refractive power. The fixed-focus lens satisfies |F1/F|<1.35, 3.5<|F2/F|<4.5, and 4<|F3/F|<5, wherein F1 is the effective focal length (EFL) of the first lens group, F2 is the EFL of the second lens group, F3 is the EFL of the third lens group, and F is the EFL of the fixed-focus lens.

Abstract: A zoom lens includes a first lens group and a second lens group disposed between the first lens group and an image side. The first lens group has three lenses. Refractive powers of the three lenses arranged from an object side to the image side are respectively negative, negative, and positive. The second lens group has five lenses. Refractive powers of the five lenses arranged from the object side to the image side are respectively positive, negative, positive, negative, and positive. Effective focal lengths (EFL) of the first and the second groups are respectively f1 and f2. The EFL of the zoom lens is fw when the zoom lens is switched to a wide end. The zoom lens satisfies ?2.8<f1/fw<?2.5 and 0.75<|f1/f2|<0.9.

Abstract: A fixed-focus lens including a first lens group, a second lens group, and a third lens group arranged in sequence from a magnified side towards a reduced side is provided. The first lens group has a positive refractive power, and includes a first lens and a second lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the first lens and the second lens are respectively negative and positive. The second lens group has a positive refractive power, and includes a third lens, a fourth lens, and a fifth lens arranged in sequence from the magnified side towards the reduced side. Refractive powers of the third lens, the fourth lens, and the fifth lens are respectively positive, negative, and positive. The third lens group has a positive refractive power, and includes a sixth lens. A refractive power of the sixth lens is positive.

Abstract: A zoom lens including a first lens group with a negative refractive power and a second lens group with a positive refractive power is provided. The first lens group is composed of a first lens, a second lens, and a third lens. Refractive powers of the first lens, the second lens, and the third lens are respectively negative, negative, and positive. Moreover, the second lens group is disposed between the first lens group and an image side. The second lens group is composed of a fourth lens, a fifth lens, and a sixth lens. Refractive powers of the fourth lens, the fifth lens, and the sixth lens are respectively positive, negative, and positive. The first lens group and the second lens group are capable of moving between an object side and the image side. The zoom lens has advantages of wide angle and small volume.

Abstract: A zoom lens includes a first lens group and a second lens group disposed between the first lens group and an image side. The first lens group has three lenses. Refractive powers of the three lenses arranged from an object side to the image side are respectively negative, negative, and positive. The second lens group has five lenses. Refractive powers of the five lenses arranged from the object side to the image side are respectively positive, negative, positive, negative, and positive. Effective focal lengths (EFL) of the first and the second groups are respectively f1 and f2. The EFL of the zoom lens is fw when the zoom lens is switched to a wide end. The zoom lens satisfies ?2.8<f1/fw<?2.5 and 0.75<|f1/f2|<0.9.

Abstract: A fixed-focus lens adapted to be disposed between a magnified side and a reduced side is provided. The fixed-focus lens includes a first lens group, a second lens group, and a third lens group. The first lens group disposed between the magnified side and the reduced side includes three lenses and has a negative refractive power. The second lens group disposed between the first lens group and the reduced side includes five lenses and has a positive refractive power. The third lens group disposed between the second lens group and the reduced side includes five lenses and has a positive refractive power. The fixed-focus lens satisfies |F1/F|<1.35, 3.5<|F2/F|<4.5, and 4<|F3/F|<5, wherein F1 is the effective focal length (EFL) of the first lens group, F2 is the EFL of the second lens group, F3 is the EFL of the third lens group, and F is the EFL of the fixed-focus lens.

Abstract: A fixed focus lens includes, numbered in order of location from an object side to an image side, a first lens, a second lens, a third lens, and a fourth lens. The first lens is a biconvex lens with a positive refractive power, and the second lens is a convex-concave lens with a negative refractive power. The third lens is a concave-convex lens with a positive refractive power, and the fourth lens is an aspherical lens having a negative refractive power in the centre portion thereof and a positive refractive power at the periphery portion thereof. The fixed focus lens satisfies the condition: 1.0>|(1/r2?1/r1)|>0.6, where r1 denotes the radius of curvature of a front surface of the second lens and r2 denotes the radius of curvature of a rear surface of the first lens.

Abstract: A projection lens includes a first lens group with a negative refractive power, a second lens group with a negative refractive power, and a third lens group with a positive refractive power, wherein the second lens group is disposed between the first lens group and the third lens group. The first lens group includes an aspheric lens. The second lens group includes a first lens and a second lens. The third lens group includes a third lens, a forth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens.

Abstract: A zoom lens suitable for imaging an object on a photosensitive device is provided. The zoom lens includes a first lens group, a second lens group, a third lens group and a fourth lens group, which are arranged in series. The fourth lens group is disposed near the photosensitive device. The second lens group and the third lens group are suitable for moving between the first lens group and the fourth lens group. The first lens group, the second lens group, the third lens group and the fourth lens group include at least a glass lens and a plurality of plastic lenses. The number of the plastic lenses is more than the number of glass lenses. Thus, overall cost of producing the zoom lens is lower.

Abstract: A zoom lens including a first lens group with a negative refractive power and a second lens group with a positive refractive power is provided. The first lens group includes a first lens, a second lens, and a third lens arranged from an object side to an image side in sequence. The refractive powers of the first, second, and third lenses are negative, negative, and positive sequentially. The second lens group includes a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged from the object side to the image side in sequence. The refractive powers of the fourth, fifth, sixth, and seventh lenses are positive, positive, negative, and positive sequentially. The first lens group and the second lens group are capable of moving between the object side and the image side.

Abstract: A fixed-focus lens including a first lens, a second lens, a cemented lens, an aperture stop, and a fifth lens is provided. The first lens disposed between an object side and an image side has a negative refractive power. The second lens disposed between the first lens and the image side has a positive refractive power. The cemented lens is disposed between the second lens and the image side. The cemented lens consists of a third lens and a fourth lens arranged in sequence from the object side to the image side. One of the third lens and the fourth lens has a positive refractive power, and the other has a negative refractive power. The aperture stop is disposed between the fourth lens and the image side. The fifth lens disposed between the aperture stop and the image side has a positive refractive power.

Abstract: A zoom lens including a first lens group with a negative refractive power and a second lens group with a positive refractive power is provided. The first lens group includes a first lens, a second lens, and a third lens arranged from an object side to an image side in sequence. The refractive powers of the first, second, and third lenses are negative, negative, and positive sequentially. The second lens group includes a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged from the object side to the image side in sequence. The refractive powers of the fourth, fifth, sixth, and seventh lenses are positive, positive, negative, and positive sequentially. The first lens group and the second lens group are capable of moving between the object side and the image side.

Abstract: A zoom lens suitable for imaging an object on a photosensitive element is provided. The zoom lens includes a first lens group, a second lens group disposed between the first lens group and the photosensitive element, a third lens group disposed between the second lens group and the photosensitive element, and a fourth lens group. The second lens group is suitable for moving between the first lens group and the third lens group. The third lens group includes two lenses having positive refractive power. The fourth lens group is disposed and suitable for moving between the third lens group and the photosensitive element. The refractive powers of the first lens group, the second lens group, the third lens group, and the fourth lens group are a positive value, a negative value, a positive value, and a positive value respectively.

Abstract: A zoom lens including a first lens group with a negative refractive power and a second lens group with a positive refractive power is provided. The first lens group is composed of a first lens, a second lens, and a third lens. Refractive powers of the first lens, the second lens, and the third lens are respectively negative, negative, and positive. Moreover, the second lens group is disposed between the first lens group and an image side. The second lens group is composed of a fourth lens, a fifth lens, and a sixth lens. Refractive powers of the fourth lens, the fifth lens, and the sixth lens are respectively positive, negative, and positive. The first lens group and the second lens group are capable of moving between an object side and the image side. The zoom lens has advantages of wide angle and small volume.