Sharp corners, minimal distortion, reduced vignetting. The 5-element/4-group design with ultra-high-index tantalum-based optical glass ensures good optical performance and optimized corner sharpness, distortion, and reduced vignetting. Like the revolutionary original Metabones Speed Booster announced in January 2013, the Speed Booster Ultra has a magnification of 0.71x, thereby reducing the crop factor of DSLR cameras with DX sensors, such as Sony E-Mount and Fuji X-Mount cameras, from 1.5x to 1.07x. The Ultra design effectively utilizes exotic materials at the cutting edge of glass manufacturing technology, making it suitable for nearly all full-frame DSLR lenses. This allows the adapter to correct regardless of the exit pupil distance. Therefore, the Speed Booster Ultra is excellent for professional f/2.8 zoom lenses, such as Canon and Nikon's 24-70mm f/2.8 and 70-200mm f/2.8 zoom lenses, converting them into 17-50mm f/2.0 and 50-142mm f/2.0 high-speed zoom lenses, respectively. Similarly, high-speed prime lenses, such as a 50mm f/1.2 lens, are transformed into a 35.5mm f/0.9 lens with excellent contrast and resolution from the center to the edge of the image.