Optical system and image pickup apparatus having the same

An apparatus comprising:

• a system;
• and
• a sensor configured to receive an image formed by the system,
• wherein the system includes, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a third lens unit having positive refractive power,
• wherein each distance between adjacent lens units changes during focusing,
• wherein during focusing from an infinity object to the closest object, the first and third lens units do not move and the second lens unit moves toward the image side,
• wherein the third lens unit consists of, in order from the object side to the image side, a first subunit having positive refractive power, a second subunit having negative refractive power, and a third subunit having positive refractive power,
• wherein the second subunit moves in a direction including a component in a direction orthogonal to an optical axis during image stabilization,
• wherein the second subunit includes a positive lens and a negative lens, and
• wherein the following inequalities are satisfied:
• 1.90<N3b_ave
• f3b/f<−0.25
• 2.5<LDis/BF<6.5
• where N3b_ave is an average value of refractive indices of all lenses included in the second subunit, f3b is a focal length of the second subunit, and f is a focal length of the system, LDis is a distance on the axis from a lens surface closest to an object in the second subunit to an image plane, and BF is a distance on the axis from a lens surface closest to the image plane of the system to the image plane.

An optical system comprising, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a third lens unit having positive refractive power,

• wherein each distance between adjacent lens units changes during focusing,
• wherein during focusing from an infinity object to the closest object, the first and third lens units do not move and the second lens unit moves toward the image side,
• wherein the third lens unit consists of, in order from the object side to the image side, a first subunit having positive refractive power, a second subunit having negative refractive power, and a third subunit having positive refractive power,
• wherein the second subunit moves in a direction including a component in a direction orthogonal to an optical axis during image stabilization,
• wherein the second subunit includes a positive lens and a negative lens, and
• wherein the following inequalities are satisfied:
• 1.90<N3b_ave
• f3b/f<−0.25
• 3.8<f1/BF<7.0
• where N3b_ave is an average value of refractive indices of all lenses included in the second subunit, f3b is a focal length of the second subunit, f is a focal length of the optical system, f1 is a focal length of the first lens unit, and BF is a distance on the axis from a lens surface closest to an image plane of the system to the image plane.

An optical system comprising, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a third lens unit having positive refractive power,

• wherein each distance between adjacent lens units changes during focusing,
• wherein during focusing from an infinity object to the closest object, the first and third lens units do not move and the second lens unit moves toward the image side,
• wherein the third lens unit consists of, in order from the object side to the image side, a first subunit having positive refractive power, a second subunit having negative refractive power, and a third subunit having positive refractive power,
• wherein the second subunit moves in a direction including a component in a direction orthogonal to an optical axis during image stabilization,
• wherein the second subunit includes a positive lens and a negative lens, and
• wherein the following inequalities are satisfied:
• 1.90<N3b_ave
• f3b/f<−0.25
• −5.5<f2/BF<6.5
• where N3b_ave is an average value of refractive indices of all lenses included in the second subunit, f3b is a focal length of the second subunit, f is a focal length of the optical system, f2 is a focal length of the second lens unit, and BF is a distance on the axis from a lens surface closest to an image plane of the system to the image plane.

An optical system comprising, in order from an object side to an image side, a first lens unit having positive refractive power, a second lens unit having negative refractive power, and a third lens unit having positive refractive power,

• wherein each distance between adjacent lens units changes during focusing,
• wherein during focusing from an infinity object to the closest object, the first and third lens units do not move and the second lens unit moves toward the image side,
• wherein the third lens unit consists of, in order from the object side to the image side, a first subunit having positive refractive power, a second subunit having negative refractive power, and a third subunit having positive refractive power,
• wherein the second subunit moves in a direction including a component in a direction orthogonal to an optical axis during image stabilization,
• wherein the second subunit includes a positive lens and a negative lens, and
• wherein the following inequalities are satisfied:
• 1.90<N3b_ave
• f3b/f<−0.25
• 5.0<f3/BF<8.5
• where N3b_ave is an average value of refractive indices of all lenses included in the second subunit, f3b is a focal length of the second subunit, f is a focal length of the optical system, f3 is a focal length of the third lens unit, and BF is a distance on the axis from a lens surface closest to an image plane of the system to the image plane.