Abstract: The aperture of a zoom lens is varied automatically during zooming by an aperture drive device that includes a pair of drive members rotatable about the optical axis. Each drive member has an arm member that engages a coupling member on a rocking member pivoted about an axis perpendicular to the optical axis. During an aperture closing operation the coupling member and the arm members move relatively along the optical axis. Initially, both drive members rotate together, such that the aperture does not change, but then the drive members rotate relatively to vary the aperture.

Abstract: A clamping device for camera accessories includes a cylindrical adaptor member defining a lens hood. The inner periphery of the adaptor member is formed with an annular collar member which has an internal diameter smaller than the external diameter of a collar formed on the outer sleeve of a lens barrel along a V-shaped groove which is formed on the outer periphery of the outer sleeve. The collar member serves to prevent the hood from connecting with the lens barrel at an undesirable position.

Abstract: In an interchangeable lens for a camera, at least three terminals are provided on the fixing cylinder of the lens. A variable diaphragm resistor exhibiting a resistance value corresponding to the diaphragm value set by the diaphragm drive ring of the lens and a variable range resistor exhibiting a resistance value corresponding to the film-to-subject distance set by the range ring of the lens are series connected between two of the terminals. A resistance value representing the guide number information is generated between the two terminals. The remaining one of the terminals is connected to the junction between the variable diaphragm resistor and the variable range resistor, and a resistance value representing the diaphragm information or the range information is generated between the remaining one terminal and the two terminals.