The invention relates to a compact two-group zoom optical system which has an
angle of view of 70 or greater at the wide-angle end and satisfactory image-formation
capability all over the zoom range while maintaining a zoom ratio of 3 or greater.
The zoom optical system comprises a first lens group G1 having positive
refracting power and a second lens group G2 having negative refracting power.
For zooming from the wide-angle end to the telephoto end, the respective lens groups
move toward the object side while the spacing between the first lens group G1
and the second lens group G2 becomes narrow.
