| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a projection zoom lens not susceptible to a temperature difference even when it occurs inside the projection zoom lens. <P>SOLUTION: When at least two lenses L2 and L3 that are resin lenses having power with different signs are disposed comparatively not apart from each other in a lens group at an enlargement side with respect to an aperture diaphragm S, a temperature difference between the lenses L2 and L3 can be made small, and a variation amount of focus in a projection zoom lens 40 as a whole can be made small. Lens groups G1 to G3 at the enlargement side with respect to the aperture diaphragm S are close to ambient air, and temperature rise during use is comparatively small. Therefore, by disposing the lenses L2 and L3 that are resin lenses susceptible to temperature rise at the enlargement side with respect to the aperture diaphragm S, focus shift in accordance with temperature variation can be reliably reduced. <P>COPYRIGHT: (C)2013,JPO&INPIT |
