IMAGING OPTICAL SYSTEM AND OPTICAL APPARATUS INCLUDING THE SAME

摘要

An imaging optical system includes a first lens unit having a negative refractive power, a second lens unit having a positive refractive power, a third lens unit having a positive refractive power, a fourth lens unit, and a fifth lens unit, and the first lens unit includes a first negative lens and a first cemented lens, the second lens unit includes a second cemented lens and one or more positive lens components, the third lens unit includes one or more positive lens components and a third cemented lens, and the first cemented lens includes a negative lens closest to the reduction side and has a concave surface facing the reduction side, the second cemented lens has a positive refractive power and has a concave surface facing the enlargement side, the third cemented lens has a positive refractive power and has a negative lens on the reduction side.

主权项

1. An imaging optical system configured to form a conjugate relation between a conjugate point on an enlargement side having a long distance and a conjugate point on a reduction side having a short distance,
the imaging optical system comprising: in order from the enlargement side, a first lens unit having a negative refractive power; a second lens unit having a positive refractive power; a third lens unit having a positive refractive power; a fourth lens unit; and a fifth lens unit, wherein an aperture stop is included in the second lens unit, the first lens unit includes a first negative lens positioned closest to the enlargement side and a first cemented lens positioned closest to a reduction side, the second lens unit includes, in order from the enlargement side, a second cemented lens and at least one positive lens component, the third lens unit includes, in order from the enlargement side, at least one positive lens component and a third cemented lens, the lens component is a lens block in which an enlargement-side surface and a reduction-side surface alone are in contact with air in an optical path, the first cemented lens includes a negative lens closest to a reduction side and has a surface closest to the reduction side having a concave surface facing the reduction side, the second cemented lens has a positive refractive power and has a surface closest to the enlargement side having a concave surface facing the enlargement side, and the third cemented lens includes a positive refractive power and has a negative lens on the reduction side.