Optical system and image pickup apparatus including the same

An image pickup apparatus, comprising:

• an optical system including, in order from an object side to an image side, a front unit having a plurality of lenses, an aperture stop, and a rear unit having a positive refractive power;
• and
• an image pickup element configured to receive an image formed by the optical system,
• wherein the front unit includes a positive lens and three or more negative lenses, and wherein the optical systems satisfies conditional expressions:
• θgF+0.00163×νd>0.665,
• νd<20.00,
• −0.30<f/ff<0.25,
• 2.00<(GnR1+GnR2)/(GnR1−GnR2)<8.00, and
• 18.09≤TD/f<45.0,
• where νd and θgF respectively represent an Abbe number and a partial dispersion ratio of a material of a negative lens Gn having a smallest Abbe number among negative lenses included in the front unit, ff represents a focal length of the front unit, and f represents a focal length of the optical system, GnR1 represents a curvature radius of an object-side lens surface of the negative lens Gn, GnR2 represents a curvature radius of an image-side lens surface of the negative lens Gn, and TD represents a distance on an optical axis from a lens surface of the front unit closest to the object side to a lens surface of the rear unit closest to the image side.

An optical system comprising in order from an object side to an image side:

• a front unit including a plurality of lenses;
• an aperture stop;
• and
• a rear unit having a positive refractive power,
• wherein the front unit includes a positive lens and three or more negative lenses, and
• wherein the optical system satisfies conditional expressions:
• θgF+0.00163×νd>0.665,
• νd<20.00, and
• −0.30<f/ff<0.25,
• 2.00<(GnR1+GnR2)/(GnR1−GnR2)<8.00, and
• 18.09≤TD/f<45.00,
• where νd and θgF respectively represent an Abbe number and a partial dispersion ratio of a material of a negative lens Gn having a smallest Abbe number among the negative lenses included in the front unit, ff represents a focal length of the front unit, and f represents a focal length of the optical system, GnR1 represents a curvature radios of an object-side lens surface of the negative lens Gn, GnR2 represents a curvature radios of an image-side lens surface of the negative lens Gn, TD represents a distance on an optical axis from a lens surface of the front unit closest to the object side to a lens surface of the rear unit closest to the image-side, and
• wherein the optical system is a fixed focal length optical system.