| US 7,331,693 B2 | ||
| Zoom lens and image pickup apparatus including the same | ||
| Toyokatsu Fujisaki, Utsunomiya (Japan) | ||
| Assigned to Canon Kabushiki Kaisha, Tokyo (Japan) | ||
| Filed on Aug. 22, 2006, as Appl. No. 11/466,177. | ||
| Claims priority of application No. 2005-246015 (JP), filed on Aug. 26, 2005. | ||
| Prior Publication US 2007/0047103 A1, Mar. 01, 2007 | ||
| Int. Cl. F21V 5/00 (2006.01) | ||
| U.S. Cl. 362—326 [362/17; 362/18; 362/299; 359/680; 359/689] | 11 Claims |
| 1. A zoom lens comprising, in order from an object side to an image side:
a first lens unit with a negative refractive power;
a second lens unit with a positive refractive power; and;
a third lens unit with a negative refractive power,
wherein the second lens unit and the third lens unit move during zooming,
wherein the first lens unit includes a negative biconcave lens element, and
wherein the following conditions are satisfied:
−1.4<φ1/φw<−1.0
0.9<φ2/φw<1.4
−1.3<φ3/φw<−0.9
where φ1 is a refractive power of the first lens unit, φ2 is a refractive power of the second lens unit, φ3 is a refractive
power of the third lens unit, and φw is a refractive power of the entire system at a wide-angle end.
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