The Metabones Speedbooster rocks! 

Kauai wedding photographer Difraser uses new Speedbooster to make fast lens even faster

I received the Metabones speedbooster today, opened the package, popped the device on my GH4, threw on my cheapy Canon 50mm 1.8 and the meter on the camera read F1.2—that’s what the speedbooster is supposed to do, and by golly it does. I then tried it out with my 70–200 IS, then my Rokinon 85mm 1.4, which was suddenly an F0.8, absolutely dazzling! I’m not so certain that I’ll only be doing photo with my 5D and 6D anymore.