Abstract: The camera accessory is attachable to a camera by relatively rotating from a first state to a second state. Camera side contact pins include a first camera side contact pin making contact with an accessory side contact holding portion in the first state and second camera side contact pins not making contact with the accessory side contact holding portion in the first state. Accessory side contact surfaces include a first accessory side contact surface making contact with the first camera side contact pin in the second state and second accessory side contact surfaces not making contact with the first camera side contact pin in the second state. A pitch between the first and second accessory side contact surfaces adjacent thereto is larger than a pitch between the second accessory side contact surfaces adjacent to each other.

Abstract: A first lens unit performing communication with an image pickup apparatus with a first voltage and a second lens unit performing communication with the image pickup apparatus with a second voltage are selectively attached to the image pickup apparatus. The image pickup apparatus includes a controller configured to operate with a third voltage different from at least one of the first and second voltages to output a signal for the communication with the first and second lens units, and a determiner configured to determine the type of the lens unit attached to the image pickup apparatus. The controller is configured to produce, as a voltage of the signal for the communication, from the third voltage, one of the first and second voltages corresponding to a determination result of the determiner.

Abstract: The image projection apparatus is disclosed to which plural interchangeable optical units are selectively attachable. The apparatus includes a shift mechanism moving an attached optical unit, which is one of the plural interchangeable optical units that is attached to the apparatus, with respect to a light modulation element in a direction orthogonal to an optical axis, an actuator driving the shift mechanism, and a controller controlling drive of the actuator using a control parameter for moving the attached optical unit by a specific movement amount via the shift mechanism. The controller acquires information on at least one of a weight and an optical characteristic of the attached optical unit from a memory provided in one of the apparatus and the attached optical unit, and to change the control parameter using the acquired information.