Image pickup apparatus, accessory, and imaging system

An image pickup apparatus to which an accessory is detachably attached, the image pickup apparatus comprising:

• a first terminal and a second terminal configured to communicate with the accessory;
• and
• a control unit configured to be capable of switching between a first communication mode in which information about the accessory is received through the second terminal in synchronization with a clock signal output through the first terminal and a second communication mode in which information about the accessory is received through the first terminal and the second terminal without the synchronization with the clock signal,
• wherein in the second communication mode, the control unit transmits an instruction to drive an optical member included in the accessory through the second terminal and receives information indicating whether the optical member is being driven through the first terminal, and
• wherein the information about the accessory indicates that the optical member is being driven when a signal level of the first terminal is a first level and indicates that the optical member is being stopped when a signal level of the first terminal is a second level different from the first level.

An accessory detachably attached to an image pickup apparatus, the accessory comprising:

• an optical member;
• a first accessory terminal and a second accessory terminal configured to communicate with the image pickup apparatus;
• and
• an accessory control unit configured to be capable of switching between a first communication mode in which a clock signal is received through the first accessory terminal and information about the accessory is transmitted through the second accessory terminal on the basis of the clock signal and a second communication mode in which information about the accessory is transmitted through the first accessory terminal and the second accessory terminal without receiving a clock signal through the first accessory terminal,
• wherein in the second communication mode, the accessory control unit receives an instruction to drive the optical member through the second accessory terminal and transmits information indicating whether the optical member is being driven through the first accessory terminal, and
• wherein the accessory control unit controls the signal level of the first accessory terminal to be a first level when the optical member is driven and controls the signal level of the first accessory terminal to be a second level different from the first level when the optical member is being stopped.

An accessory detachably attached to an image pickup apparatus, the accessory comprising:

• an optical member;
• a first accessory terminal and a second accessory terminal configured to communicate with the image pickup apparatus;
• and
• an accessory control unit configured to be capable of switching between a first communication mode in which information about the accessory is transmitted through the second accessory terminal in synchronization with a clock signal received through the first accessory terminal and a second communication mode in which information about the accessory is transmitted through the first accessory terminal and the second accessory terminal without the synchronization with the clock signal,
• wherein in the second communication mode, the accessory control unit receives an instruction to drive the optical member through the second accessory terminal and transmits information indicating whether the optical member is being driven through the first accessory terminal, and
• wherein the accessory control unit controls the signal level of the first accessory terminal to be a first level when the optical member is driven and controls the signal level of the first accessory terminal to be a second level different from the first level when the optical member is being stopped.

An imaging system comprising:

• an image pickup apparatus;
• and
• an accessory detachably attached to the image pickup apparatus,
• wherein the image pickup apparatus is capable of communicating with the accessory through a first communication line and a second communication line,
• wherein the imaging system is capable of switching between a first communication mode in which a clock signal is communicated through the first communication line and information about the accessory is communicated through the second communication line on the basis of the clock signal a second communication mode in which information about the accessory is communicated without communicating a clock signal through the first communication line,
• wherein, in the second communication mode, the accessory transmits information about the accessory to the image pickup apparatus through the first communication line and the second communication line and the image pickup apparatus receives information about the accessory through the first communication line and the second communication line,
• wherein in the second communication mode, the image pickup apparatus transmits an instruction to drive an optical member included in the accessory through the second communication line and receives information indicating whether the optical member is being driven through the first communication line, and
• wherein the accessory controls the signal level of the first communication line to be a first level when the optical member is being driven and controls the signal level of the first communication line to be a second level different from the first level when the optical member is being stopped.