| 摘要 |
PURPOSE:To realize easy handling and to move a lens barrel forth in a watertight state by forming an internal and an external air chamber in the lens barrel, and linking the internal air chamber with the internal space of a camera and the external air chamber with the outside of the camera. CONSTITUTION:When the lens barrel 2 is moved to the rearmost position to serve as a wide-angle lens, the internal space 6 of the camera is small and the capacity of the internal air chamber 5B is large. When the lens barrel 2 is drawn out to the front to enters a telephoto lens state, the camera internal space 6 becomes large and the capacity of the internal air chamber 5B decreases to allow the air in the internal air chamber 5B to move into the internal space 6 through a vent hole 3a and a vent passage 2b, so that the air pressure in the internal space 6 is held constant. Then when the lens barrel 2 is slid from the telephoto position to the wide-angle position, the internal space 6 becomes small and the capacity of the internal air chamber 5B increases to allow the air in the internal space 6 to flow in the internal chamber 5B from the vent hole 3a through the vent passage 2b. Therefore, the pressure in the camera internal space 6 is still held constant and thus the lens barrel 2 is switched between the wide-angle and telephoto states while held in the airtight state.
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