The RF 15-35mm f/2.8L IS USM from Canon is also characterized by its bright f/2.8 constant maximum aperture. This bright design enables working in available light conditions and also affords greater control over the depth of field. An Air-Sphere coating has also been applied to reduce flare and ghosting for improved contrast and color fidelity when working in bright conditions. A unique Control Ring is also integrated into the lens design for intuitive control over exposure settings from the lens itself. Constant f/2.8 maximum aperture maintains consistent illumination throughout the zoom range and suits working in available light conditions. Three aspherical elements are used to correct spherical aberrations and distortion for improved sharpness and accurate rendering. An Optical Image Stabilizer helps to minimize the appearance of camera shake by five stops to better enable working in low-light conditions and with slower shutter speeds. Configurable Control Ring can be used to adjust a variety of exposure settings, including aperture, ISO, and exposure compensation.