Speed Booster XL 0.64x A new Micro-4/3 mount Speed Booster adapter designed exclusively for the Panasonic GH4 and other selected Micro Four Thirds cameras (refer to the below camera compatbility table), with a magnification of 0.64x. The Speed Booster XL 0.64x uses an advanced 6-element optical design to achieve extraordinary optical performance at apertures up to an incredible f/0.80, a new record for Micro Four Thirds format. The new Speed Booster XL 0.64x reduces the full-frame crop factor of the Panasonic GH4 from 2.0x to 1.28x, thus effectively transforming these cameras into APS-H format.When the GH4 is used in Cinema 4k video mode the horizontal full frame crop factor is reduced from 2.34x to 1.50x, thus effectively transforming the GH4 into a super-35 format 4k cine camera. In addition, the speed of any attached lens is increased by 11/3 stops, with a maximum output aperture of f/0.80 when an f/1.2 lens is used. For example, a 50mm f/1.2 becomes a 32mm f/0.80, which is the fastest aperture available for full size Micro Four Thirds format. 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 & F lens (include non-AI & AI lens mounts) Increase maximum aperture by 1 1/3 stops Increase MTF Makes lens 0.64x wider Click-less manual G aperture ring Support Panasonic GH4, GH3, G3, G5, G6, G10, GF3