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.