摘要 |
A projection lens of the following structure was invented for the purpose of providing a bright projection optical system with the F-number of approximately 2 or lower while maintaining good optical characteristics, in an image display apparatus. The projection lens is constructed of six lens units, a first lens unit L<HIL><PDAT>1 </BOLD><PDAT>of a negative optical power, a second lens unit L<HIL><PDAT>2 </BOLD><PDAT>of a positive optical power, a third lens unit L<HIL><PDAT>3 </BOLD><PDAT>of a positive optical power, a fourth lens unit L<HIL><PDAT>4 </BOLD><PDAT>of a negative optical power, a fifth lens unit L<HIL><PDAT>5, </BOLD><PDAT>and a sixth lens unit L<HIL><PDAT>6 </BOLD><PDAT>of a positive optical power, in the order named from the enlargement conjugate side, and four lens units (L<HIL><PDAT>2 </BOLD><PDAT>to L<HIL><PDAT>5</BOLD><PDAT>) out of the lens units move toward the enlargement conjugate side during zooming from the wideangle extreme to the telephoto extreme.</PTEXT>
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