Zoom optical system, optical instrument incorporating the zoom optical system, and method of manufacturing the zoom optical system

摘要

A zoom optical system has a first lens group having a positive refracting power; a second lens group having a negative refracting power; a third lens group having a positive refracting power; a fourth lens group having a negative refracting power; and a fifth lens group having a positive refracting power, in the order from the object side. The fourth lens group is composed of a cemented lens of a negative lens and a positive lens in the order from the object side, and a condition of the following expression is satisfied:
vp > 30.0, where vp is an Abbe number of the positive lens.