the main way to achieve deep focus was closing down the aperture, which required increasing the lighting intensity, lenses with better light transmission, and faster film stock. on "citizen kane", the cameras and coated lenses used were of toland's own design working in conjunction with engineers from caltech. his lenses were treated with vard opticoat to reduce glare and increase light transmission. he used the kodak super xx film stock, which was, at the time, the fastest film available, with an asa film speed of 100. toland had worked closely with a kodak representative during the stock's creation before its release in october 1938, and was one of the first cinematographers using it heavily on set.