A light amount adjusting apparatus is constructed by a driving source, a plurality
of light shielding members each having a notched portion adapted to form a light
passing port, in which the light shielding member is moved by being driven by the
driving source to thereby vary an area of the light passing port which is formed
in the notched portion, and at least one filter provided for the notched portions
of the plurality of light shielding members, in which the filter is provided so
as to cover a part of the notched portion and has a first area having first light
transmittance and a second area having second light transmittance lower than the
first light transmittance. When the area of the light passing port which is formed
by the light shielding members is in a maximum state, a relation (A321)
is satisfied assuming that, in the light passing port, A1 indicates an area
of a portion which is not covered with the filter, A2 indicates an area
of a portion covered with the first area of the filter, and A3 indicates
an area of a portion covered with the second area of the filter.
