Abstract: Provided are a wafer scale lens, which is so short in an optical total length with respect to an image height that it can correct an aberration satisfactory, and an optical system including the wafer scale lens and having a thin lens element on the side closest to the image. The optical system includes a first lens having a positive refractive power relative to an object, and a second lens arranged on the side of the image of the first lens and having a recessed shape on the side of the object. At least one lens is arranged on the side of the second lens.

Abstract: The present invention provides a wafer-scale lens in which a total optical length is short in comparison with an image height and astigmatism and other aberrations can be well corrected, and an optical system in which a lens element closest to the object side is thin in thickness. The optical system includes a first lens that is disposed closest to the object side and is positive in refractive power; a second lens that is disposed on the image side and has a concave surface on the object side; an i-th lens, (i?3), that is disposed closest to the image side in lenses disposed on the image side and includes an i-th lens plate and a lens element which is formed on at least either the object side surface or the image side surface of the i-th lens plate, and has a refraction index different from the i-th lens plate and positive or negative refractive power; and satisfies 0.9>Ymax/Y>0.

Abstract: An image pickup lens includes a first lens block with a positive power and a second lens block with a positive or negative power. The first lens block includes a first lens substrate, and lens portions 1a and 1b arranged on opposing surfaces of the first lens substrate. The lens portions 1a and 1b are different from the first lens substrate in at least one of a refractive index and an Abbe number. The second lens block includes a second lens substrate, and lens portions 2a and 2b arranged on opposing surfaces of the second lens substrate. The lens portions 2a and 2b are different from the second lens substrate in at least one of a refractive index and an Abbe number. The image pickup lens satisfies a condition relating to focal lengths of the lens portions 1a and 2b.

Abstract: A variable-power optical system includes, in order from an object side thereof: a first lens group with a negative optical power; a second lens group with a positive optical power; a third lens group with a negative optical power; and a fourth lens group with a positive optical power. An interval between the first lens group and the second lens group decreases when a power of the variable-power optical system varies from a wide-angle end to a telephoto end. The second lens group includes at least one aspheric surface. The variable-power optical system satisfies the predetermined conditional expressions.

Abstract: A variable-power optical system includes, in order from an object side thereof: a first lens group with a negative optical power; a second lens group with a positive optical power; and a third lens group with a negative optical power, where an interval between the first lens group and the second lens group decreases when a power of the variable-power optical system varies from a wide-angle end to a telephoto end. The first lens group comprises a negative lens and a positive lens. The second lens group consists of a positive lens and a negative lens, and includes at least one aspheric surface. The variable-power optical system satisfies the predetermined conditional expressions.

Abstract: A variable-power optical system includes, in order from an object side thereof: a first lens group with a negative optical power; a second lens group with a positive optical power, moving when the power of the variable-power optical system varies; and a third lens group with a positive or negative optical power. The first lens group includes two or more lenses including one positive lens and one negative lens which include at least two or more lenses made of a plastic material. The variable-power optical system satisfies the predetermined conditional expressions relating to is a focal length of the first lens, a focal length of the second lens, a composite focal length of the total optical system, and an image-forming magnification of the second lens group at a telephoto end.

Abstract: The present invention provides an image pickup lens for forming a light flux from a subject into an image on an image pickup element, and the image pickup lens includes, in order from an object side thereof: an aperture stop; a first lens having a positive refractive power; a second lens having a negative refractive power and comprising a concave surface facing an image side of the image pickup lens; a third lens having a positive refractive power; and a fourth lens having a negative refractive power and comprising a concave surface facing the image side. The image pickup lens satisfies the predetermined condition according to a curvature radius of the surface facing the image side on the second lens, and a focal length of the image pickup lens.

Abstract: The present invention provides an image pickup lens for forming a light flux from a subject into an image on an image pickup element, and the image pickup lens includes, in order from an object side thereof: an aperture stop; a first lens having a positive refractive power; a second lens having a negative refractive power and comprising a concave surface facing an image side of the image pickup lens; a third lens having a positive refractive power; and a fourth lens having a negative refractive power and comprising a concave surface facing the image side. The image pickup lens satisfies the predetermined condition according to a curvature radius of the surface facing the image side on the second lens, and a focal length of the image pickup lens.