Thomas Sutton first patented the lens on which the camera relies, in September 1859.[1][2] The lens is constructed as two glass hemispheres, enclosing a water-filled spherical space. Supposedly, Sutton was inspired by the view through a 'snowstorm' souvenir from Paris;[1] however, the glass parts of the lens are thick-walled: in the example in the Museum of the History of Science in Oxford, the glass hemispheres are 80 mm in diameter, and enclose a 36 mm-diameter space. In the central space, there is a diaphragm, shaped to equalise the exposure across the wide view.[1][2] The lens is an f/12.