An optical apparatus is provided with a zoom optical system. The zoom optical system includes a lens unit located at the most object-side position and a moving lens unit with positive refracting power, located on the image side of the lens unit. The lens unit includes a single positive lens and the moving lens unit is simply moved toward the object side when the magnification of the zoom lens is changed in the range from a wide-angle position to a telephoto position so as to satisfy the following condition:

0.8y₀₇/(fwtan _07w)0.96

where fw is the focal length of the entire system of the zoom lens at the wide-angle position, y₀₇ is an image height expressed by 0.7y₁₀, where y₁₀ is a distance from the center to a point farthest therefrom on the effective imaging surface of an electronic image sensor, and _07w is an angle made by a direction of an object point with an optical axis, where the object point corresponds to an image point that is at the point y₀₇ away from the center on the effective imaging surface of the electronic image sensor at the wide angle position.