| 摘要 |
A zoom lens comprising, in order from the object side to the image side, a first lens unit having a positive refractive power which does not move for zooming, a plurality of lens units which move during zooming, and a rear lens unit having a positive refractive power which does not move for zooming, wherein the refractive index, the Abbe constant, the partial dispersion ratio and the focal length of the positive lens located closest to the image side among the positive lenses in the first lens unit and the focal length of the first lens unit, the focal length of the positive lens located closest to the image side among the positive lenses in the first lens unit, and the focal length of the first lens unit are appropriately set. |
| 主权项 |
1. A zoom lens comprising, in order from the object side to the image side:
a first lens unit having a positive refractive power which does not move for zooming; a plurality of lens units which move during zooming; and a rear lens unit having a positive refractive power which does not move for zooming; wherein the zoom lens satisfies the following conditions:
0.6545<θp+0.002×νp<0.6660,43.0<νp<57.0,2.210<Np+0.01×νp<2.320,1.72<Np<1.80, and2.10<|fp/f1|<2.70,where Np, νp, and θp are the refractive index, the Abbe constant and the partial dispersion ratio of the positive lens located closest to the image side among the positive lenses in the first lens unit respectively, fp is the focal length of the positive lens located closest to the image side among the positive lenses in the first lens unit, and f1 is the focal length of the first lens unit, the Abbe constant ν and the partial dispersion ratio θ being defined as follows:
ν=(Nd−1)/(NF−NC), and θ=(Ng−NF)/(NF−NC),were Ng, NF, Nd, and NC are refractive indexes for the g-line, F-line, d-line, and C-line respectively. |
