Optical system, optical apparatus, and method for manufacturing the optical system

A method for manufacturing a fixed focal length optical system including a continuous series of six lenses consisting of, in order from an object, consecutively, a first lens having negative refractive power, a second lens having positive refractive power, a third lens having positive refractive power, a fourth lens having negative refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power,

• the method comprising assembling each lens in a lens barrel so as to satisfy the following conditional expression:
• 0.88<L4R2/f
• where L4R2 denotes a radius of curvature of an image side surface of the fourth lens, and f denotes a focal length of the total lens system,
• wherein
• the following conditional expression is satisfied:
• −1.000 <(L5R1+L4R2)/(L5R1−L4R2)<−0.310
• where L5R1 denotes a radius of curvature of an object side surface of the fifth lens, and
• wherein the first lens is a negative meniscus lens closest to the object and has a concave surface facing the image, and wherein the continuous series of six lenses is devoid of lens elements between successive lenses of the series.

A fixed focal length optical system, comprising a continuous series of six lenses consisting of, in order from an object, consecutively:

• a first lens having negative refractive power;
• a second lens having positive refractive power;
• a third lens having positive refractive power;
• a fourth lens having negative refractive power;
• a fifth lens having negative refractive power;
• and
• a sixth lens having positive refractive power, and
• the following conditional expressions being satisfied:
• 1.52<L3R1/f3
• −1.000 <(L5R1+L4R2)/(L5R1−L4R2)<−0.310
• where L3R1 denotes a radius of curvature of an object side lens surface of the third lens,
• f3 denotes a focal length of the third lens, and
• L5R1 denotes a radius of curvature of an object side surface of the fifth lens, and
• L4R2 denotes a radius of curvature of an image side surface of the fourth lens,
• wherein the first lens is a negative meniscus lens closest to the object and has a concave surface facing the image,
• wherein the continuous series of six lenses is devoid of lens elements between successive lenses of the series, and
• wherein the fifth lens is a bi-concave lens or a negative lens having a concave surface facing the object.

A method for manufacturing a fixed focal length optical system including a continuous series of six lenses consisting of, in order from an object, consecutively, a first lens having negative refractive power, a second lens having positive refractive power, a third lens having positive refractive power, a fourth lens having negative refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power,

• the method comprising assembling each lens in a lens barrel so as to satisfy the following conditional expressions:
• 1.52<L3R1/ f3
• −1.000 <(L5R1+L4R2)/(L5R1−L4R2)<−0.310
• where L3R1 denotes a radius of curvature of an object side lens surface of the third lens,
• f3 denotes a focal length of the third lens,
• L5R1 denotes a radius of curvature of an object side surface of the fifth lens, and
• L4R2 denotes a radius of curvature of an image side surface of the fourth lens,
• wherein the first lens is a negative meniscus lens closest to the object and has a concave surface facing the image,
• wherein the continuous series of six lenses is devoid of lens elements between successive lenses of the series, and
• wherein the fifth lens is a bi-concave lens or a negative lens having a concave surface facing the object.

A fixed focal length optical system, comprising a continuous series of six lenses consisting of, in order from an object, consecutively:

• a first lens having negative refractive power;
• a second lens having positive refractive power;
• a third lens having positive refractive power;
• a fourth lens having negative refractive power;
• a fifth lens having negative refractive power;
• and
• a sixth lens having positive refractive power, and
• the following conditional expressions being satisfied:
• 1.52<L3R1/f3
• 0.88<L4R2/f
• where L3R1 denotes a radius of curvature of an object side lens surface of the third lens,
• f3 denotes a focal length of the third lens,
• L4R2 denotes a radius of curvature of an image side surface of the fourth lens, and
• f denotes a focal length of the total lens system,
• wherein the first lens is a negative meniscus lens closest to the object and has a concave surface facing the image,
• wherein the continuous series of six lenses is devoid of lens elements between successive lenses of the series, and
• wherein the fifth lens is a bi-concave lens or a negative lens having a concave surface facing the object.

A method for manufacturing a fixed focal length optical system including a continuous series of six lenses consisting of, in order from an object, consecutively, a first lens having negative refractive power, a second lens having positive refractive power, a third lens having positive refractive power, a fourth lens having negative refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power,

• the method comprising assembling each lens in a lens barrel so as to satisfy the following conditional expressions:
• 1.52<L3R1/f3
• 0.88<L4R2/f
• where L3R1 denotes a radius of curvature of an object side lens surface of the third lens,
• f3 denotes a focal length of the third lens,
• L4R2 denotes a radius of curvature of an image side surface of the fourth lens, and
• f denotes a focal length of the total lens system,
• wherein the first lens is a negative meniscus lens closest to the object and has a concave surface facing the image,
• wherein the continuous series of six lenses is devoid of lens elements between successive lenses of the series, and
• wherein the fifth lens is a bi-concave lens or a negative lens having a concave surface facing the object.