Method of operating an authentication system for a vehicle, wherein a vehicle BLE interface (3, 3', 3") is arranged on the vehicle, wherein an optical detection device (4, 4', 4") is arranged on the vehicle, and wherein a portable authentication transmitter (5a, 5a', 5a") having an authentication transmitter BLE interface (5b, 5b', 5b") is provided, with the steps: Performing a BLE-based communication between the vehicle BLE interface (3, 3', 3") and the authenticator BLE interface (5b, 5b', 5b"), Evaluating of BLE-based communication on the vehicle side, Controlling the optical detection device (4, 4', 4") in dependence on the evaluation of the BLE-based communication for optical position determination or distance determination of an operator who carries the portable authentication transmitter (5a, 5a', 5a"), wherein evaluating the BLE-based communication comprises determining a signal strength of the BLE-based communication, wherein the vehicle BLE interface and at least a second vehicle BLE interface (3") are provided on the vehicle, the optical detection device and at least a second optical detection device (4") are provided on the vehicle, the vehicle BLE interface is associated with the optical detection device, the second vehicle BLE interface (3") is associated with the second optical detection device (4"), and the one of the at least two optical detection devices (4', 4") associated with the one of the at least two vehicle BLE interfaces (3', 3") which has performed the BLE-based communication within a predetermined time period t S for which the strongest signal strength has been determined with the portable authentication transmitter (5a, 5a', 5a") has been determined, such that the comparison of signal strengths of the BLE-based communication at different vehicle BLE interfaces located at different positions of the vehicle is used to select that particular one of several existing optical detection devices for which the greatest possible success of an optical detection of the operator is to be expected. wherein a vehicle BLE interface (3, 3', 3") is arranged on the vehicle, wherein an optical detection device (4, 4', 4") is arranged on the vehicle, and wherein a portable authentication transmitter (5a, 5a', 5a") having an authentication transmitter BLE interface (5b, 5b', 5b") is provided, with the steps: Performing a BLE-based communication between the vehicle BLE interface (3, 3', 3") and the authenticator BLE interface (5b, 5b', 5b"), Evaluating of BLE-based communication on the vehicle side, Controlling the optical detection device (4, 4', 4") in dependence on the evaluation of the BLE-based communication for optical position determination or distance determination of an operator who carries the portable authentication transmitter (5a, 5a', 5a"), wherein evaluating the BLE-based communication comprises determining a signal strength of the BLE-based communication, wherein the vehicle BLE interface and at least a second vehicle BLE interface (3") are provided on the vehicle, the optical detection device and at least a second optical detection device (4") are provided on the vehicle, the vehicle BLE interface is associated with the optical detection device, the second vehicle BLE interface (3") is associated with the second optical detection device (4"), and the one of the at least two optical detection devices (4', 4") associated with the one of the at least two vehicle BLE interfaces (3', 3") which has performed the BLE-based communication within a predetermined time period t S for which the strongest signal strength has been determined with the portable authentication transmitter (5a, 5a', 5a") has been determined, such that the comparison of signal strengths of the BLE-based communication at different vehicle BLE interfaces located at different positions of the vehicle is used to select that particular one of several existing optical detection devices for which the greatest possible success of an optical detection of the operator is to be expected. Performing a BLE-based communication between the vehicle BLE interface (3, 3', 3") and the authenticator BLE interface (5b, 5b', 5b"), Evaluating of BLE-based communication on the vehicle side, Controlling the optical detection device (4, 4', 4") in dependence on the evaluation of the BLE-based communication for optical position determination or distance determination of an operator who carries the portable authentication transmitter (5a, 5a', 5a"), wherein evaluating the BLE-based communication comprises determining a signal strength of the BLE-based communication, wherein the vehicle BLE interface and at least a second vehicle BLE interface (3") are provided on the vehicle, the optical detection device and at least a second optical detection device (4") are provided on the vehicle, the vehicle BLE interface is associated with the optical detection device, the second vehicle BLE interface (3") is associated with the second optical detection device (4"), and the one of the at least two optical detection devices (4', 4") associated with the one of the at least two vehicle BLE interfaces (3', 3") which has performed the BLE-based communication within a predetermined time period t S for which the strongest signal strength has been determined with the portable authentication transmitter (5a, 5a', 5a") has been determined, such that the comparison of signal strengths of the BLE-based communication at different vehicle BLE interfaces located at different positions of the vehicle is used to select that particular one of several existing optical detection devices for which the greatest possible success of an optical detection of the operator is to be expected.