Patent ID: 6927926

Claim:
A telephoto lens comprising, in order from an object side: a first lens unit having a positive refracting power; a second lens unit having a negative refracting power; a third lens unit having a positive refracting power; and a fourth lens unit having a negative refracting power, wherein the second lens unit comprises a cemented lens composed of a positive lens and a negative lens, and a negative lens, wherein the fourth lens unit comprises a cemented lens composed of a negative lens and a positive lens, and a negative lens, and wherein the telephoto lens satisfies the following conditions ν d >8 0.5>ƒ 4 /ƒ>−1.2 where ν d is an Abbe's number of a lens having a positive refracting power in the first lens unit,ƒ 4 is a focal length of the fourth lens unit, and ƒis a focal length of an entire optical system.