"Industry's best aperture ring covers a 8-stop range, clearly indicating actual number of f-stops. No more guesswork! (Patent pending) Compatible to both Nikkor G lens and F lens (include non-AI and AI lens mounts) Increase maximum aperture by 1 stop Increase MTF Makes lens 0.71x wider Patented 5-element/4-group optical design incorporating ultra-high index tanatalum-based optical glass by Caldwell Photographic in the USA The tripod foot is detachable and compatible with Arca Swiss, Markins, Photo Clam ball heads Always Enhance and Never Degrade the Performance of the Attached Master Lens Like the ULTRA series for Sony E-mount, the new Speed Booster ULTRA m43 uses an advanced 5-element 4-group optical design incorporating ultra-high index tantalum-based optical glass. However, the new design is specifically optimized 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 m43 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 len"