Abstract: The body of a filter holder carrying a filter has a slot in which an engaging member is disposed for rotation between first and second positions in response to rotation of a shaft to which the engaging member is attached. In a first position of the shaft, retaining means on the engaging member is retracted within the slot for effecting insertion of the holder into a lens barrel. In a second position of the shaft, the retaining means projects from and is engageable with the lens barrel for retaining the body thereto.

Abstract: A lens tube for a single-lens reflex camera having a plurality of aperture blades normally pressed in the aperture-enlarging direction comprises an interlocking member operably associated with the aperture blades, a limiting member for stopping the interlocking member to determine the position of the blades for providing a desired aperture, a release means provided in interlocked relation with the shutter mechanism on the camera body and an operating member actuated from the outside to operate the interlocking member until the interlocking member is stopped by the limiting member during the initial stage of operation and to thereafter operate the release means. The lens tube can be incorporated in the conventional follow-up type aperture-controlled camera.