| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize miniaturization and the improvement of optical performance by specifying magnification relation between a 2nd lens group and a 3rd lens group at a telephoto end and the magnification of a 3rd lens group. SOLUTION: This zoom lens is composed of the 1st lens group (i) having positive refractive power, the 2nd lens group (ii) having negative refractive power and the 3rd lens group (iii) having the positive refractive power in order from an object side, and a diaphragm 12 is attached between the 2nd and the 3rd lens groups (ii) and (iii). By moving the 2nd and the 3rd lens groups (ii) and (iii) along an optical axis, zooming is carried out from a wide-angle end to the telephoto end. Then, the zoom lens is constituted to satisfy an expression: 2.0<β2(T)/β3(T)<2.5 and an expression: -0.7<β3(T)<-0.4. In the expressions,β(T) means the magnification of the respective lens groups at the telephoto end. Furthermore, the power of the 3rd lens group (iii) is expressed by an expression: 0.6<f(W)/f(3)<0.8. In the expression, f(W) is the focal distance of the zoom lens at the wide-angle end and f(3) means the focal distance of the 3rd lens group (iii).</p> |
