The Contax Yashica Lens to Fujifilm X-Mount Camera Speed Booster ULTRA from Metabones improves upon the original Metabones Speed Booster with a 5 element/4 group optical design that incorporates ultra-high refractive index tantalum-based glass for improved sharpness and reduced distortion and vignetting. The Speed Booster ULTRA allows a full frame Contax Yashica lens to be mounted to an APS-C format X-Mount camera and in doing so increases the angle of view and increases the maximum aperture by approximately one f/stop. When a lens intended for full frame sensors or 35mm film is mounted to a camera with an APS-C sized sensor it transmits a larger area of light than the smaller sensor was built to accept and therefore the effective angle of view of the lens increases. The Speed Booster condenses light from the lens and projects it onto the APS-C sensor allowing the sensor to utilize all of the lens light and effectively reduces the crop factor of and APS-C E-Mount camera from 1.5x to 1.07x producing a full-frame angle of view with an APS-C sensor. A corresponding increase in the maximum aperture of one f/stop makes the lens more effective in low-light situations and able to create a shallow depth of field. Although the lens will fit physically automatic diaphragm (AE metering) or other auto functions are not retained using this speed booster. Metabones Speed Boosters are quality made using precision-machined brass with chromium plating on both the camera body and the lens side of the booster in order to ensure smooth mounting quality aesthetic and durability. A matte black interior reduces internal reflections and a black satin finish external surface matches with most camera bodies and lenses. This adapter has a tripod foot that is compatible with Arca Swiss Markins and Photo Clam ball heads and can be removed if needed with an included hex key. Allows a full frame Contax Yashica lens to be mounted to an Fujifilm X-mount APS-C format camera and in doing so increa.