Last week I finished a short film that we shot on the GH3 with the Speed Booster. I thought it's maybe interesting for you guys to hear and see how it holds up in the field.
At first I received a faulty Speed Booster, but the 2nd one worked great. It feels solid and well designed, although there is a little 'play' on the camera mount side. Nothing to worry about though. It makes my lenses wider and better. There is some purple fringing though at low light shots when pointing at a light source, but this is only at very large apertures. The lenses are perfectly usable at high apertures in 'normal' situations with the Speed Booster. It didn't hold me back while I was shooting with it, so that's great. I see no increase or decrease in sharpness without pixel peeping. Simply to say, it's ignorable and you can shoot safely.
I'm a real fan of the Samyang primes. I have the 16mm f2.0 / 35mm f1.4 / 85mm f1.4.
They feel and look solid and professional. Image quality is great. Usuable wide open, but really good stopped down 1 - 2 stops. Thanks to the Speed Booster I love my GH3 even more now. With a crop factor of around 1.4x, it's comparible to a S35 sensor. So I now have the 6 most used focal lenghts (with normal adapter / speed booster), an effective s35 sensor when I need it and all the good stuff and quality that I'm used to from the GH3.
Maybe you guys are interested in the short film. It's a short comedy film (5 min) and is, with a few exceptions, shot with the Speed Booster.
Here is the link:
Would love to hear your opinions about it Hope I could provide some insight and thanks for watching. :)