LIGHT QUANTITY REGULATING DEVICE AND OPTICAL SYSTEM HAVING IT AND PHOTOGRAPHING DEVICE

摘要

An optical performance is deteriorated by the minute transmitting wave−front phase difference of an ND filter. A light quantity regulating device which is provided with an ND filter (P1) that attenuates the quantity of light passing through an aperture formed by diaphragm blades (S11, S12), and is changed in a ratio at which the ND filter (P1) shields the opening, wherein the phase difference of light having a specified wavelength &lgr; and passing through areas (N11, N12, N13), different in transmittance, of the ND filter (P1) in the opening when the opening is fully shielded by the filter (P1) is set to be almost 0&lgr;, 1&lgr; or 2&lgr;.