Abstract: Provided is an optical system in which chromatic aberrations can be excellently corrected in spite of environmental changes, to thereby maintain high optical performance. The optical system includes: a plurality of optical elements each having refractive surfaces located in a light incident side and a light exit side; and an aperture stop. A focal length, an Abbe number of a material, and an extraordinary partial dispersion ratio of each of an l-th optical element and an r-th optical element which satisfy a condition related to the extraordinary partial dispersion ratio are suitably set.

Abstract: An optical element is provided, which is small in distortion when at least three optical members including a resin layer sandwiched by the optical members are cemented together, has a high environmental resistance and optical performance, and has an excellent chromatic aberration correction effect. In the optical element, the resin layer is formed on one of light incident/exit surfaces of a first optical member, and a second optical member is cemented to the resin layer by a bonding material. A condition of ?g<?r is satisfied where ?r indicates an outer diameter of the resin layer and ?g indicates an effective region diameter of a surface of the second optical member which is cemented to the resin layer.

Abstract: A zoom lens includes a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, which are arranged in order from the object side to the image side. The zoom lens performs zooming by changing a distance between the lens units. The first lens unit includes a compound optical element including a lens element and a resin layer having optical characteristics different from optical characteristics of the lens element, the resin layer being laminated on the lens element. An Abbe number ?dg of a material of the lens element, an Abbe number ?dj of a material of the resin layer, and an anomalous partial dispersion ratio ??gFj of the material of the resin layer are adequately set.

Abstract: Provided is an optical system in which chromatic aberrations can be excellently corrected in spite of environmental changes, to thereby maintain high optical performance. The optical system includes: a plurality of optical elements each having refractive surfaces located in a light incident side and a light exit side; and an aperture stop. A focal length, an Abbe number of a material, and an extraordinary partial dispersion ratio of each of an l-th optical element and an r-th optical element which satisfy a condition related to the extraordinary partial dispersion ratio are suitably set.

Abstract: A zoom lens includes a first lens unit having a negative refractive power and a second lens unit having a positive refractive power, which are arranged in order from the object side to the image side. The zoom lens performs zooming by changing a distance between the lens units. The first lens unit includes a compound optical element including a lens element and a resin layer having optical characteristics different from optical characteristics of the lens element, the resin layer being laminated on the lens element. An Abbe number ?dg of a material of the lens element, an Abbe number ?dj of a material of the resin layer, and an anomalous partial dispersion ratio ??gFj of the material of the resin layer are adequately set.

Abstract: An optical system includes an optical member made of a solid material being a mixture prepared by dispersing inorganic particles in a transparent medium. The transparent medium and the inorganic particles of the solid material, and the volume ratio of the inorganic particles to the transparent medium are set so that the optical system can appropriately correct aberrations such as chromatic aberrations.

Abstract: An optical system includes an optical member made of a solid material being a mixture prepared by dispersing inorganic particles in a transparent medium. The transparent medium and the inorganic particles of the solid material, and the volume ratio of the inorganic particles to the transparent medium are set so that the optical system can appropriately correct aberrations such as chromatic aberrations.

Abstract: In an optical system, there is disposed a solid material having refractive surfaces on both of the light incidence side and a light emergence side, and the Abbe number vd and the partial dispersion ratio ?gF satisfy the conditions: ?2.100×10?3·vd+0.693<?gF; and 0.555<?gF<0.6.

Abstract: In an optical system, there is disposed a solid material having refractive surfaces on both of the light incidence side and a light emergence side, and the Abbe number ?d and the partial dispersion ratio ?gF satisfy the conditions: ?2.100×10?3·?d+0.693<?gF; and 0.555<?gF<0.6.