| 摘要 |
PURPOSE:To improve imaging performance at an intermediate angle of view by providing a variable aperture diaphragm near the 1st lens on the object side of a rear attachment lens and stopping down the variable aperture diaphragm in interlocking with the diaphragm of a photographic lens. CONSTITUTION:A variable aperture diaphragm P is arranged right in front of the 1st lens on the object side of a rear attachment lens B and when the diaphragm V of a photographic lens A is stopped down from an open aperture to an intermediate aperture, it is also stopped down in interlocking with the V. In this case, the aperture of the variable aperture diaphragm P so determines to limit luminous flux L2 at a maximum angle of view without limiting luminous flux L on an axis determining an F number, and the quantity of peripheral light is not reduced. Consequently, only luminous flux L1', which becomes a flare component, of luminous flux at an intermediate angle of view is removed efficiently, improving imaging performance at the intermediate angle of view. |
