Patent ID: 11874527
Assignee: CANON KABUSHIKI KAISHA
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. An image pickup apparatus comprising:
a reduction optical system disposed on an image side of a main optical system; and
an image pickup element configured to pick up an image formed via the reduction optical system,
the reduction optical system including a plurality of positive lenses and a plurality of negative lenses,
wherein the reduction optical system has a positive refractive power,
wherein a composite focal length of the main optical system and the reduction optical system is shorter than a focal length of the main optical system, and
wherein the following inequalities are satisfied:

0.50<β<0.78,

0.20<fp1/f<1.30, and

1.895<Np1<2.150,

where β is a lateral magnification of the reduction optical system disposed on the image side of the main optical system, f is a focal length of the reduction optical system, fp1 is a focal length of a positive lens Gp1 included in the plurality of positive lenses, and Np1 is a refractive index of the positive lens Gp1.