I have a GH4 with the first MFT to EF speedbooster and I’ve been very impressed. It allows the amazing GH4 to perform with great cine primes and EF stills. I just got the update that allows for autofocus and let me tell you; this is a killer combo.
The speedbooster, if you don’t know, is a reverse teleconverter that gets you more width and more f/stop (.78x and +1 f-stop) as well as being an electronic MFT to EF adapter. Previously you had aperture control in camera for EF lenses, and with the new firmware (1.7) you get AF control too.
- its slower, that’s a consequence of phase detection lenses on contrast detection bodies...nothing new here
- It wont autofocus in video mode. Bummer, but not a deal breaker
- It doesn’t power IS in the lens (if it has it)
That being said, I’m really impressed for what it is. I’ve tried it with a 70-200 non-IS, a 16-35 L, a 24-70 L and the 100mm f.2.8 macro and they are all fast, and accurate. These were all shot and are strait out of camera in a 5 minute walkaround today. Low light is a little slower, but not much.
Very impressed with the speedbooster (original, not S or Cine) and the update. It means I can invest in Canon glass and Panasonic bodies. Win/Win.