Image-forming optical apparatus having a decentered optical surface

In an image-forming optical apparatus comprising an objective optical system and an electronic image pickup device which is disposed in a plane where an image of an object is formed by said objective optical system,

• the improvement wherein said objective optical system has at least one reflecting surface decentered such that a whole of said surface is tilted with respect to an axial principal ray defined by a light ray emanating from a center of the object and passing through a center of a pupil to reach a center of the object image,
• said reflecting surface having a rotationally asymmetric surface configuration that corrects rotationally asymmetric decentration aberrations caused by decentration, and
• wherein a low-pass member is disposed in a vicinity of a pupil plane closer to the object than said reflecting surface, said low-pass member cutting off a high-frequency component concerning the object image in a bundle of light rays led to said electronic image pickup device.