| 摘要 |
An imaging lens system has, from the object side, a first lens group having a positive optical power, a second lens group having a positive optical power, and a third lens group having a positive optical power. During focusing from an object at infinity to an object at a close distance, while the first and third lens groups remain stationary relative to an image surface, the second lens group moves toward the object side. The second lens group has at least one negative lens element. The conditional formulae 0.2 < P1 / P < 0.6, 0.3 < P1 / P2 < 0.9, and 0.45 < (PI + P3) / P < 1.0 are fulfilled (P1, P2, and P3 representing the optical powers of the first, second, and third lens groups respectively, P representing the optical power of the entire system in the infinity shooting condition). |
