Zoom optical system, imaging lens device, and digital apparatus

An imaging lens device comprising a zoom optical system including:

• a first reflecting prism configured to bend an incident ray at about 90 degrees by reflection, and having an incident surface disposed on a subject side of an optical path and an exit surface disposed on an object side of said optical path;
• a second reflecting prism configured to bend an incident ray at about 90 degrees by reflection, and having an incident surface disposed on the subject side of an optical path and an exit surface disposed on the object side of said optical path, and
• at least one lens group including one or more lens elements arranged between the exit surface of the first reflecting prism and the incident surface of the second reflecting prism,
• the incident surface of the first reflecting prism, and the exit surface of the second reflecting prism being aligned substantially parallel to each other, the incident surface or the exit surface of the first reflecting prism having an optical power, and, if the incident surface of the first reflecting prism has an optical power, the incident surface of the second reflecting prism has an optical power or, if the exit surface of the first reflecting prism has an optical power, the exit surface of the second reflecting prism has an optical power, wherein the reflecting surface of the reflecting prisms are flat,
• an optical axis of the lens group and an axis of the optical path between the first and second reflecting prisms being coincident with each other, the lens group being movable along the optical axis thereof for zooming, and
• the zoom optical system having such a configuration as to form an optical image of a subject on a predetermined imaging plane of the zoom optical system.

A digital apparatus comprising:

• an imaging lens device;
• an image sensor;
• and
• a functioning section which causes the imaging lens device and the image sensor to execute at least one of shooting a still image of the subject, and shooting a moving image of the subject,
• the imaging lens device including a zoom optical system having:
• a first reflecting prism configured to bend an incident ray at about 90 degrees by reflection, and having an incident surface disposed on a subject side of an optical path and an exit surface disposed on an object side of said optical path;
• a second reflecting prism configured to bend an incident ray at about 90 degrees by reflection, and having an incident surface disposed on the subject side of an optical path and an exit surface disposed on the object side of said optical path, and
• at least one lens group including one or more lens elements arranged between the exit surface of the first reflecting prism and the incident surface of the second reflecting prism,
• the incident surface of the first reflecting prism, and the exit surface of the second reflecting prism being aligned substantially parallel to each other, the incident surface or the exit surface of the first reflecting prism having an optical power, and, if the incident surface of the first reflecting prism has an optical power, the incident surface of the second reflecting prism has an optical power or, if the exit surface of the first reflecting prism has an optical power, the exit surface of the second reflecting prism has an optical power, wherein the reflecting surface of the reflecting prisms are flat,
• an optical axis of the lens group and an axis of the optical path between the first and second reflecting prisms being coincident with each other, the lens group being movable along the optical axis thereof for zooming, and
• the zoom optical system having such a configuration as to form an optical image of a subject on a predetermined imaging plane of the zoom optical system.