| 摘要 |
A projection lens system for an image projection apparatus that enhances the image aberration correction rate to achieve high resolution and luminance. The lens system includes a first lens group having first and second spherical lenses of positive refraction power movable along an optical axis, a second lens group having a third doublet lens formed with a lens of positive refraction power and a lens of negative refraction power in junction to correct chromatic aberration, and a fourth spherical lens to correct spherical aberration, a third lens group having lenses of positive refraction power, and a fourth lens group for correcting distortions having a seventh spherical lens being concave on both surfaces thereof, an eighth spherical lens of negative refraction power having a concave surface on one side and a convex surface on the other side, and a ninth lens of negative refraction power having an aspheric surface.
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