Patent ID: 8179612

Claim:
A lens barrel unit comprising: a lens holding cylinder configured to hold a lens; a cam cylinder including a cam groove configured to engage with the lens holding cylinder and define a movement of the lens holding cylinder in an optical axis direction; a straightforward movement cylinder inserted into the cam cylinder, and configured to engage with the cam cylinder and move with the cam cylinder in the optical axis direction, a light shield provided at the top of the cam cylinder and configured to form an opening, wherein the lens holding cylinder includes a ring-shaped step that projects outward in a radial direction, wherein in an image pickup state, a surface of the ring-shaped step which is an end of an object side in the ring-shaped step is closer to an object than a surface of the straightforward movement cylinder which is an end of an object side in the straightforward movement cylinder, wherein a diameter of the opening of the light shield is larger than an external diameter of the lens holding cylinder, and a diameter of the ring-shaped step is larger than the diameter of the opening of the light shield, and wherein an amount by which the ring shaped step projects outward in the radial direction is configured so that, in image pickup state, light does not proceed to an aperture between the straightforward movement cylinder and the ring-shaped step in a direction perpendicular to the optical axis direction, the light proceeding into the lens barrel unit from an aperture between a circumference of the opening of the light shield and the lens holding cylinder in the direction perpendicular to the optical axis direction.