Optical system and imaging apparatus including the same

An optical system comprising:

• a first lens unit, a second lens unit having a negative refractive power, a third lens unit, and a fourth lens unit having a positive refractive power arranged in that order from an object side to an image side,
• wherein intervals between adjacent ones of the lens units change during focusing,
• wherein the second lens unit moves toward the image side and the fourth lens unit moves toward the object side during focusing from infinity to close range, and
• wherein the first lens unit includes a negative meniscus lens and a positive lens, the negative meniscus lens having a convex surface facing the object side.

An imaging apparatus comprising:

• an optical system;
• and
• an imaging device configured to receive an image formed by the optical system,
• wherein the optical system includes a first lens unit, a second lens unit having a negative refractive power, a third lens unit, and a fourth lens unit having a positive refractive power arranged in that order from an object side to an image side,
• wherein intervals between adjacent ones of the lens units change during focusing,
• wherein the second lens unit moves toward the image side and the fourth lens unit moves toward the object side during focusing from infinity to close range, and
• wherein the following inequality is satisfied:
• -
• 10.
• <
• f
• ⁢
• 2
• /
• f
• <
• -
• 3.6
• where f2 is a focal length of the second lens unit and f is a focal length of an entire system.