Imaging apparatus and exposure control method used for the same

An imaging apparatus comprising:

• a shutter drive section opening and closing a shutter for a light receiving surface of a solid state image sensor;
• an aperture blade drive section driving an aperture blade forming an aperture for an imaging lens;
• an ND filter drive section adjusting a position of an ND filter against the aperture, the ND filter adjusting light intensity of an optical object image received on the light receiving surface of the solid state image sensor;
• a light intensity detection section detecting the light intensity of the optical object image received on the light receiving surface of the solid state image sensor and outputting a light intensity signal based on the light intensity of the optical object image;
• a memory storing an exposure control table indicating corresponding relationships among an F value determined by an area of the aperture and the position of the ND filter against the aperture, a shutter speed in opening and closing the shutter, and an exposure control voltage representing an exposure amount;
• and
• a control section calculating the target exposure control voltage from the light intensity signal;
• reading out the F value corresponding to the exposure control voltage from the exposure control table;
• determining whether or not there exists a possibility of a partial application state of the ND filter, in which the ND filter is applied to a part of the aperture, when controlling the aperture blade drive section and the ND filter drive section using the F value;
• reading out the shutter speed corresponding to the F value from the exposure control table if the possibility of the partial application state of the ND filter is determined not to exist;
• reading out the F value again from the exposure control table so as to avoid the partial application state of the ND filter if the possibility of the partial application state of the ND filter is determined to exist and reading out the shutter speed corresponding to the F value which is read out again from the exposure control table;
• controlling the aperture blade drive section and the ND filter drive section according to the F value read out from the exposure control table;
• and controlling the shutter drive section according to the shutter speed read out from the exposure control table, for carrying out exposure control.