Metabones MB_SPEF-M43-BT5 Canon EF Lens to Micro Four Thirds T CINE Speed Booster ULTRA 0.71x (p/n MB_SPEF-m43-BT5). Like the ULTRA series for Sony E-mount, the new Speed Booster ULTRA uses an advanced 5-element 4-group optical design incorporating ultra-high index tantalum-based optical glass.  However, the new design is specifically optimised for the Micro Four Thirds sensor and filter stack, and as a result, achieves an astonishing level of performance that sets a new standard for focal reducers.
 Like the revolutionary original Metabones Speed Booster® announced in January 2013, the Speed Booster ULTRA has a magnification of 0.71x, and so it effectively reduces the crop factor of mirrorless Micro Four Thirds mount cameras from 2.0x to 1.4x.  However, the new ULTRA design makes very effective use of exotic materials at the furthest limit of glassmaking technology, and as a result is almost perfectly corrected for use with all fullframe SLR lenses regardless of aperture.  The Speed Booster ULTRA will also work extremely well with many...