| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a zoom lens for projection with a large field angle that has various aberrations excellently reduced with a simple constitution of a limited small number of lenses. <P>SOLUTION: The zoom lens for projection includes a 1st negative lens group (10) comprising one meniscus lens 11 whose object-point side surface 11a is an aspherical surface, a 2nd positive lens group (20) comprising one 2nd-group lens, a 3rd negative lens group (30) comprising a cemented lens (30a), a 4th positive lens group (40) comprising one 4th-group lens (41), and a 5th lens group (50) comprising one positive 5th-group lens (51) and is characterized in that, when the power is varied from a wide-angle end side to a telephoto-end side, the 5th lens group (50) is fixed and the 1st lens group (10), 2nd lens group (20), 3rd lens group (30), and 4th lens group (40) are all moved on the optical axis toward a screen. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
