Patent ID: 8731393
Filing Date: 2014-05-20
Classification: G03B

Abstract:
1. An optical apparatus comprising: a stop having an aperture whose size is variable; two filter members each including a first area that includes (i) a transmissive part having a transmittance of 75% or more and (ii) a gradation part having a transmittance that is lower than the transmittance of the transmissive part, the transmittance of the gradation part being changed in a moving direction of the filter member; an actuator configured to drive the two filter members; and a controller configured to control the actuator, wherein each of the stop and the two filter members is drivable, wherein the two filter members are disposed so that a changing direction of a transmittance of the gradation part and a moving direction of one of the two filter members are opposite to a changing direction of a transmittance of the gradation part and a moving direction of the other of the two filter members respectively, and the first area has a size that covers an entirety of a first aperture, which is smaller than a full open stop aperture, and the transmissive part has a size that does not cover the entirety of the first aperture, wherein the controller controls the actuator so as to move, without a halt of the two filter members, through an area between a first position where the first area of each of the two filter members is evacuated from the first aperture and a second position where the first area of each of the two filter members covers the entirety of the first aperture, the first aperture being an aperture when each of the two filter members is located at the second position, wherein the transmissive parts of the two filter members are configured to not overlap with each other in a direction orthogonal to an aperture surface of the stop when the two filter members are disposed at the second position, and wherein, while the two filter members are moving, without halting, through the area between the first position and the second position, the controller adjusts a light amount by controlling at least one of a size of the aperture of the stop, an electronic shutter velocity of an image pickup element, or a gain of the image pickup element to suppress a luminance change caused by a movement of the area between the first position and the second position.