The instrument (10) has a shaft (12) including a distal end (14), where an optical sensor (16) i.e. camera, is arranged at the distal end. The shaft includes a proximate end (18) for connecting to a supply unit (20). A data transfer element i.e. star quad cable (22), is arranged between the optical sensor and the proximate end for differentially transferring two signals. The cable includes wire pairs with respective wires, which have different diameters. A supplementary wire is provided supplying power to the optical sensor.
