Abstract: The invention is directed to an optical system (1). The optical system (1) has a housing (2) with an opening (3) extending through the housing (2) encompassing an in general constant volume (V). A membrane (6) with two or more membrane sections is arranged across the opening separating the volume (V) in a first and a second chamber (7, 8) filled with at least one fluid. The membrane is attached to an annular holding frame (9). An actuator is interconnected to the membrane (6) directly or indirectly to change the optical behaviour of the membrane.