The S4 design foregoes the usual helical thread method of focus adjustment in favor of Cooke’s Academy Award®-winning cam mechanism. The smooth cam movement liberates the lens from a simple thread rotation giving the operator an appropriate rate of focus at all distances. The cam design also allows for better spaced and more detailed and visible index marks.
The S4s are reknowned for superb control of flare, distortion, veiling glare, and spherical aberrations at full aperture.
