A camera body at which one or more camera accessories, at which light from a subject enters, are detachably mountable, includes: a body-side terminal; and a communication unit that communicates with at least one of the camera accessories, wherein: the communication unit requests, via the body-side terminal, the camera accessory for a discriminating signal indicating whether or not another camera accessory capable of communicating with the camera body is mountable on a subject side of the camera accessory.

A lens apparatus is mountable to a camera body. The camera body has multiple electric contacts. Of these multiple electric contacts, when mounting the lens apparatus to the camera body, electric contacts used for second communication or third communication come into contact with an electric contact provided to the lens apparatus before electric contacts used for first communication, when mounting the lens apparatus to the camera body.

A lens apparatus is mountable to a camera body. The camera body has multiple electric contacts. Of these multiple electric contacts, when mounting the lens apparatus to the camera body, electric contacts used for second communication or third communication come into contact with an electric contact provided to the lens apparatus before electric contacts used for first communication, when mounting the lens apparatus to the camera body.

An image capturing apparatus on which, and from which, an accessory is mountable and dismountable includes a plurality of terminals disposed in a circumferential direction of a mount, and a terminal holder. The terminal holder has a height level difference for holding the terminals at different positions in a center-axis direction of the mount. The terminals include a first terminal configured to be used to supply power for driving an internal component of the accessory, and a second terminal configured to indicate a ground level corresponding to the first terminal. The second terminal is disposed nearer in a mount direction of the accessory than the other terminals on a predetermined stage of the terminal holder, and is connected to a corresponding one of a plurality of terminals of the accessory first among the terminals when the accessory is mounted on the image capturing apparatus.

An image capturing apparatus on which, and from which, an accessory is mountable and dismountable includes a plurality of terminals disposed in a circumferential direction of a mount, and a terminal holder. The terminal holder has a height level difference for holding the terminals at different positions in a center-axis direction of the mount. The terminals include a first terminal configured to be used to supply power for driving an internal component of the accessory, and a second terminal configured to indicate a ground level corresponding to the first terminal. The second terminal is disposed nearer in a mount direction of the accessory than the other terminals on a predetermined stage of the terminal holder, and is connected to a corresponding one of a plurality of terminals of the accessory first among the terminals when the accessory is mounted on the image capturing apparatus.

A camera body at which one or more camera accessories, at which light from a subject enters, are detachably mountable, includes: a body-side terminal; and a communication unit that communicates with at least one of the camera accessories, wherein: the communication unit requests, via the body-side terminal, the camera accessory for a discriminating signal indicating whether or not another camera accessory capable of communicating with the camera body is mountable on a subject side of the camera accessory.

A camera body includes a DCL terminal, a DLC terminal, and a LCLK terminal, that perform communication with a lens apparatus by a first voltage, or a second voltage that differs from the first voltage. The camera body also includes a DLC2 terminal that is only used when communication using the DCL terminal, DLC terminal, and LCLK terminal is performed by the first voltage. The DLC2 terminal is disposed adjacent to the LCLK terminal.

A camera body includes a DCL terminal, a DLC terminal, and a LCLK terminal, that perform communication with a lens apparatus by a first voltage, or a second voltage that differs from the first voltage. The camera body also includes a DLC2 terminal that is only used when communication using the DCL terminal, DLC terminal, and LCLK terminal is performed by the first voltage. The DLC2 terminal is disposed adjacent to the LCLK terminal.

An accessory includes: a clock transmission unit that transmits a first clock signal; a first transmission unit that transmits to the camera body information pertaining to a drive target member in synchronization with the first clock signal; a clock reception unit that receives a second clock signal from the camera body; a second transmission unit that transmits to the camera body a first value indicating a communication specification according to which the first transmission unit transmits the information to the camera body in synchronization with the second clock signal; a reception unit that receives from the camera body a second value in synchronization with the second clock signal, indicating a communication specification; and a control unit that engages the first transmission unit to start transmitting the information according to the communication specification indicated by the second value, upon receiving the second value after the first value has been transmitted.

An accessory includes: a detection terminal; a first power supply terminal through which a first power supply voltage is supplied; a first ground terminal used as a ground potential; a second power supply terminal through which a second power supply voltage is supplied; a second ground terminal used as a ground potential; a ready terminal used to indicate whether or not communication is allowed; a first data terminal that receives a first data signal; a second data terminal that outputs a second data signal; a clock terminal that outputs a clock signal; and a third data terminal that outputs a third data signal, wherein: the first ground terminal, the second power supply terminal, and the second ground terminal are positioned between the first power supply terminal and the ready terminal; and the first data terminal and the second data terminal are positioned between the ready terminal and the clock terminal.