Zoom optical system and camera comprising the same

摘要

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. The first lens group G1 consists of a first lens unit U1 having negative refracting power, a second lens unit U2 having positive refracting power and a third lens unit U3 having positive refracting power. Each lens unit consists of a single lens or a doublet. To slim down an associated camera and ensure satisfactory performance all over the zoon range, the focal length of the second lens unit U2 in the first lens group G1 should satisfy condition (1).