Patent ID: 9547161
Date: 2017-01-17
CPC Classifications: G02B

Claim:
1. A single focal length lens system comprising in order from an object side to an image side along an optical axis: a front lens unit; and a rear lens unit, wherein the single focal length lens system does not include any other lens unit on the optical axis, and the front lens unit includes in order from the object side to the image side, a first lens unit having a positive refractive power, a second lens unit having a negative refractive power, and a third lens unit having a negative refractive power, and each of the first lens unit and the second lens unit includes a positive lens and a negative lens, and the first lens unit and the second lens unit do not move, and positions thereof are fixed all the time, and an aperture stop is disposed on the image side of the second lens unit, and any one of the lens units positioned on the image side of the second lens unit is a focusing lens unit, and the focusing lens unit moves along the optical axis at the time of focusing from an object at infinity to an object at a close distance, and the following conditional expression (1) is satisfied: where, f f denotes a focal length of the single focal length lens system at the time of focusing at an object at infinity.