| 摘要 |
The invention relates to a zoom lens for DLP projector. The zoom lens of the invention comprises a focus group, a zoom group and a compensation group. The zoom group comprises three zoom units with positive, negative, positive optical power respectively. The compensation group comprises a first compensation unit, a second compensation unit, an aperture stop and a third compensation unit. Corresponding to the aperture stop, the compensation lens of the compensation units have positive radius, positive radius, positive radius and negative radius respectively. The zoom lens of the invention utilizes the zoom group and the compensation group so that firstly, the F-number of the zoom lens of the invention can be fixed at 2.2; secondly, the relative luminance of the zoom lens of the invention can be up to 60% even at extreme corner; thirdly, the tolerance of the zoom lens of the invention is comparatively excellent.
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