18mm, 25mm, 35mm, 50mm, 65mm and 85mm The 35mm set has different overall lengths (mostly due to the length of the 18mm Distagon). But the focus gears are all the same diameter. Other than slight adjustments to the position of the matte box, lens changes can be quickly accomplished. The external dimensions of all the focal lengths of the S16mm lens set are the same. This allows very fast lens changes on set. All the lenses have 80mm front diameter and integrated focus gear, all the same diameter (76mm). All the lenses are the same physical length. Lens changes can be made in about 15 seconds.