| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a variable power optical system for projection providing a constant F number during variation in power, attaining miniaturization, providing a high telecentric property and a favorable projection image and favorably applied to movie theaters. <P>SOLUTION: The variable power optical system for projection, in order from a magnification side, is disposed with: a first lens group G1 which is fixed during variation in power; a plurality of lens groups which move during variation in power; and a final lens group which is fixed during variation in power. The variable power optical system is telecentric on the reduction side. An aperture stop 3 is disposed in the final lens group and has a fixed number of apertures in the whole range of variation in power. At least a single lens is disposed in the magnification side of the aperture stop 3 in the final lens group. When Imϕ is a maximum effective image circle diameter in the reduction side, fs is a composite focal length of lenses in the reduction side of the aperture stop 3, and exP is a distance from an imaging surface in the reduction side to a paraxial exit pupil position, the variable power optical system satisfies the following conditional expressions: (1) Imϕ/fs<0.4 and (2) 30.0<¾exP¾/Imϕ. <P>COPYRIGHT: (C)2013,JPO&INPIT |
