| 摘要 |
<p>A zoom lens having fewer constituting lenses and easily keeping telecentricity. A first lens group (G<SUB>1</SUB>) through a fourth lens group (G<SUB>4</SUB>) are disposed sequentially from a projection plane (PL) side. The first lens group (G<SUB>1</SUB>) consists of three lenses, a negative lens, a positive lens and a negative lens sequentially from the projection plane (PL) side, and has a negative power. The second lens group (G<SUB>2</SUB>) consists of a total of three lenses, one positive lens, one junction lens and one junction lens sequentially from the projection plane (PL) side, and has a positive power. The third lens group (G<SUB>3</SUB>) consists of one negative lens. The fourth lens group (G<SUB>4</SUB>) consists of one positive lens. At power varying, the first lens group (G<SUB>1</SUB>) and the second lens group (G<SUB>2</SUB>) are moved with the third lens group (G<SUB>3</SUB>) and the fourth lens group (G<SUB>4</SUB>) kept fixed. The third lens group (G<SUB>3</SUB>) is moved for focusing.</p> |
