The Metabones Speed Booster has barely begun shipping and we now have the first Chinese knockoff about to appear: the US$239 Zhongyi Optical Lens Turbo, initially for the NEX E-mount system and initially as a Pentax K to E-mount adapter. Be careful, though, the Speed Booster retains focus and aperture control, while the Lens Turbo doesn't. Zhongyi has several times attempted to break into the mirrorless market, originally announcing an inexpensive 28mm f/2.8 lens, then finally producing the 35mm f/0.95 Mitakon.
Zhongyi has no real official distribution outside SE Asia, so when the Lens Turbo does appear, it's likely to be on eBay via Hong Kong distributors, as is the Mitakon lens.
