An optical system includes a first lens unit B1 having a positive refractive power, a second lens unit B2, and a third lens unit B3 disposed in order from an object side to an image side. The second lens unit B2 moves in focusing so that an interval between adjacent lens units among the first, second, and third lens units changes. The first lens unit B1 includes a positive lens G1p disposed closest to the object side and a negative lens G1n being a closest negative lens with respect to the object side. The optical system satisfies a predetermined condition.

An optical system (OL) used for an optical apparatus such as a camera (1) includes a focusing group (Gf) that moves upon focusing, a diffractive optical element (GD) disposed on an object side of the focusing group (Gf) and a negative lens element (Lin) disposed on the object side of the diffractive optical element (GD). The optical system (OL) satisfies the following expressions.

0.030<f/fpf<0.050

nd1n+0.006d1n<1.910

35<d1n

where, f: focal length of whole system in infinity focusing state fpf: focal length of diffractive optical element (GD) nd1n: refractive index of medium of negative lens element (L1n) on d-line d1n: Abbe number of medium of negative lens element (L1n) on d-line

An optical system includes one or more positive lenses and one or more negative lenses. The first positive lens is a positive lens disposed closest to an object among the one or more positive lenses. The first negative lens is a negative lens that is disposed on an image side of the first positive lens and disposed closest to the object among the one or more negative lenses. At least one of an object side surface and an image side surface of the first positive lens is an aspherical surface. At this time, a relationship between a total lens length of the optical system L0, a focal length of the optical system L0, and a distance Dpn on an optical axis from the image side surface of the first positive lens to an object side surface of the first negative lens is defined.

The invention relates to a telescope optics for a telescopic observational instrument having an objective lens, having a prism erecting system and having an eyepiece lens, wherein an image of an object generated by the objective lens is located between the prism erecting system and the eyepiece lens, and wherein the objective lens, in an order starting from the object side, comprises a first lens group G1 with a positive refractive power, a second lens group G2 with a negative refractive power and a third lens group G3, and wherein the second lens group G2 is adjustable in parallel to an optical axis for focusing, and wherein at least one lens with a negative refractive power of the third lens group G3 is adjustable perpendicularly to the optical axis for changing the position of the image, and wherein the third lens group G3 has a negative refractive power.

A projection lens system projects an image of a reduction side into a magnification side in an image projection device, a back glass being disposed on the reduction side. In the projection lens system, all of one or more negative lenses that satisfy, in a surface on the reduction side or a surface on the magnification side, condition |h/H|<2.0 defined by height h of a most off-axis principal ray and height H of an axial ray passing through a highest pupil position satisfy conditions Tn98.5% and Dn/Db0.05 defined by transmittance Tn, thickness Dn of the negative lens on an optical axis, and total thickness Db of the back glass.

A zoom lens system includes a first lens group; a second lens group; and a subsequent lens group arranged in that order from the object side. The second lens group consists of a second lens group-a, a second lens group-b, and a second lens group-c arranged in that order from the object side. A distance between the first lens group and the second lens group increases and a distance between the second lens group and the subsequent lens group decreases during a change in magnification from a short focal length end to a long focal length end. During a change in focus from infinity to a short distance, the second lens group-b is movable to the image side, and a distance between the second lens group-a and the second lens group-b and a distance between the second lens group-b and the second lens group-c are changeable.

[Problem to be Solved]

There are provided an optical system having good imaging performance, an optical apparatus, and a method for manufacturing the optical system.

[Solution]

An optical system OL used in an optical apparatus, such as a camera 1, includes a diffractive optical element GD and at least one specific lens Lp, which is a lens made of crystalline glass. The specific lens Lp satisfies the condition expressed by the following expression: gFp+0.0017dp<0.730, where gFp represents partial dispersion ratio of a medium of the specific lens Lp, and dp represents the Abbe number of the medium of the specific lens Lp at a d line.

An optical system includes a first lens unit B1 having a positive refractive power, a second lens unit B2, and a third lens unit B3 disposed in order from an object side to an image side. The second lens unit B2 moves in focusing so that an interval between adjacent lens units among the first, second, and third lens units changes. The first lens unit B1 includes a positive lens G1p disposed closest to the object side and a negative lens G1n being a closest negative lens with respect to the object side. The optical system satisfies a predetermined condition.

Provided are an optical lens assembly and an electronic apparatus including the same. The optical lens assembly includes a first lens group and a second lens group that are arranged from an object side to an image side, wherein the first lens group has positive refractive power and is fixed during focusing, and the second lens group moves along an optical axis for focusing.

A zoom lens including in order from an object side: a positive first unit configured not to move for zooming; a negative second unit configured to move to the image side for zooming to a telephoto end; and a relay lens unit configured not to move for zooming, wherein the first unit consists of five lenses including, in order from the object side, a negative lens, a positive lens, a positive lens, a positive lens and a positive lens, or six lenses including, in order from the object side, a positive lens, a negative lens, a positive lens, a positive lens, a positive lens and a positive lens, and a refractive index of the negative lens in the first unit, an Abbe number of the negative lens, a focal length of the negative lens, and a focal length of the first lens unit are appropriately set.