Variable magnification optical system

An image-taking apparatus comprising:

• a variable magnification optical system for forming an optical image of an object with a variable magnification;
• and
• an image sensor for converting the optical image into an electrical signal,
• wherein the variable magnification optical system includes an optical construction comprising, from an object side, a first reflective surface, a first movable unit, a second reflective surface, and a second movable unit,
• wherein an optical axis is bent at substantially ninety degrees by the first reflective surface and is further bent by the second reflective surface,
• wherein, during magnification variation from a wide-angle end to a telephoto end, the first and second reflective surfaces are kept in fixed positions with respect to an image surface, and the first and second movable units move along the optical axis, and
• wherein conditional formula (1) below is fulfilled:
• 1.0<TR12/y′max<12.5 (1)
• where
• TR12 represents a distance along the optical axis between the first and second reflective surfaces, and
• y′max represents a maximum image height.

A camera comprising an image-taking apparatus for optically taking in an image of a subject and then outputting an electrical signal,

• wherein the image-taking apparatus comprises:
• a variable magnification optical system for forming an optical image of an object with a variable magnification;
• and an image sensor for converting the optical image into an electrical signal,
• wherein the variable magnification optical system includes an optical construction comprising, from an object side, a first reflective surface, a first movable unit, a second reflective surface, and a second movable unit,
• wherein an optical axis is bent at substantially ninety degrees by the first reflective surface and is further bent by the second reflective surface,
• wherein, during magnification variation from a wide-angle end to a telephoto end, the first and second reflective surfaces are kept in fixed positions with respect to an image surface, and the first and second movable units move along the optical axis, and
• wherein conditional formula (1) below is fulfilled:
• 1.0<TR12/y′max<12.5 (1)
• where
• TR12 represents a distance along the optical axis between the first and second reflective surfaces, and
• y′max represents a maximum image height.