See in the dark -- with T1.4 speed and a focus ring that illuminates when you need it. External lamps are no longer necessary for the focus puller to see in the dark because this new design incorporates a simple on/off and dimmer to adjust the level of illumination desired on the aperture ring. You now have the visability you need without affecting the light coming into the camera. Cooke 5/i optics offer superb optical and mechanical performance, control of flare, distortion, veiling glare and spherical aberrations at full aperture. The cam-type focus mechanism allows for smooth focus adjustments. Modular construction increases ease of maintenance and serviceability. Cooke 5/i Prime Lenses were designed and developed in close technical collaboration with industry professionals. They are colour-matched and compatible with Cooke S4/i, miniS4/i, CXX 15-40 mm T2 S4/i Zoom, 18-100mm T3.0 and 25-250mm T3.7 and the SK4 16mm lenses.