US Patent 7227696 Zoom lens and image pickup apparatus having the same

At least one exemplary embodiment is directed to a zoom lens includes first, second, and third lens units having negative, positive, and positive refractive powers, respectively, in order from an object side to an image side and performs zooming by moving each lens unit. The first lens unit includes a negative lens whose surface on the image side has a concave shape and a positive lens whose surface on the object side has a convex shape in order from the object side to the image side. At least one surface of the negative lens has an aspheric shape.