Zoom lens optical system

摘要

Provided is a zoom lens optical system suitable for cameras using solid state imaging devices, which is designed compact, has a high zooming ratio and telecentricity, and compensates for color aberration. The zoom lens optical system includes a first lens group having a positive refractive power, for performing zooming, a second lens group having a negative refractive power, for performing zooming, a third lens group having a positive refractive power, for performing zooming, and a fourth lens group having a positive refractive power. The first, second, third, and fourth lens groups are sequentially arranged from an object and satisfy the following equations: $\frac{f_T}{f_W}>=8.0$ $0.2<=\frac{L_m}{\sqrt{f_W.f_T}}<=0.6$ where f_w denotes the overall focal length of the zoom lens optical system at the wide angle position, f_T denotes the overall focal length of the zoom lens optical system at the telephoto position, and L_III denotes the amount of movement of the third lens group from the wide angle position to the telephoto position. Zooming from the wide angle position to a telephoto position is performed so that the distance between the third lens group and the fourth lens group increases.