An intermediate accessory apparatus configured to be mounted between an interchangeable lens apparatus and an image pickup apparatus, the intermediate accessory apparatus comprising: an optical member; a storage configured to store table information about a combined optical characteristic of the interchangeable lens apparatus and the intermediate accessory apparatus, associated with identification information for the interchangeable lens apparatus and with information indicating a state of the interchangeable lens apparatus, and a processor configured to transmit information in the table information about the combined optical characteristic of the interchangeable lens apparatus and the intermediate accessory apparatus to the image pickup apparatus, wherein the accessory apparatus includes, on a side of the image pickup apparatus, one or more terminals forming a first communication channel used for communication between the image pickup apparatus and the interchangeable lens apparatus, and includes, on the side of the image pickup apparatus and separately from the one or more terminals, one or more terminals forming a second communication channel used for communication between the image pickup apparatus and the accessory apparatus, wherein the identification information for the interchangeable lens apparatus and the information indicating the state of the interchangeable lens apparatus are transmitted from the interchangeable lens apparatus to the image pickup apparatus via the first communication channel, wherein the identification information for the interchangeable lens apparatus is transmitted from the image pickup apparatus to the accessory apparatus via the second communication channel, wherein the processor is configured to transmit, of the table information, table information about a combined optical characteristic of the interchangeable lens apparatus and the accessory apparatus corresponding to the identification information for the interchangeable lens apparatus and associated with information indicating a state of the interchangeable lens apparatus to the image pickup apparatus via the second communication channel. an optical member; a storage configured to store table information about a combined optical characteristic of the interchangeable lens apparatus and the intermediate accessory apparatus, associated with identification information for the interchangeable lens apparatus and with information indicating a state of the interchangeable lens apparatus, and a processor configured to transmit information in the table information about the combined optical characteristic of the interchangeable lens apparatus and the intermediate accessory apparatus to the image pickup apparatus, wherein the accessory apparatus includes, on a side of the image pickup apparatus, one or more terminals forming a first communication channel used for communication between the image pickup apparatus and the interchangeable lens apparatus, and includes, on the side of the image pickup apparatus and separately from the one or more terminals, one or more terminals forming a second communication channel used for communication between the image pickup apparatus and the accessory apparatus, wherein the identification information for the interchangeable lens apparatus and the information indicating the state of the interchangeable lens apparatus are transmitted from the interchangeable lens apparatus to the image pickup apparatus via the first communication channel, wherein the identification information for the interchangeable lens apparatus is transmitted from the image pickup apparatus to the accessory apparatus via the second communication channel, wherein the processor is configured to transmit, of the table information, table information about a combined optical characteristic of the interchangeable lens apparatus and the accessory apparatus corresponding to the identification information for the interchangeable lens apparatus and associated with information indicating a state of the interchangeable lens apparatus to the image pickup apparatus via the second communication channel.