I've been very interested in this as well, from what I have read, the only reason that there aren't plenty of manufacturers making micro four thirds adapters with .5x focal reducer built in, is because Kodak holds the patent on them. I did have an idea I wanted to share for those experimenting with this, there seems to be difficulty in the different optical formulas of various lenses and how and where to place the reducer lens in the optical path for the desired result. Consider this, the one constant in the optical path of a lens design is the distance from the lens mount to the sensor. If you construct a tube/adapter that places the reducer optics at the specific distance from the mount where the sensor would be, you should be able to "capture" the light path with a known size and focal plane, specifically the size and focal plane that the lens was designed for and the sensor expects to see. I understand that the angle of the optical path coming from the last element of the lens may vary, but I just wanted to throw the idea out there and see if it helps. Granted placing the reducer optics at that point will make the overall construction of the adapter quite long and cumbersome.

@mnryan @Brian202020 Anything at all?

@jleo, we have separate topic now

http://www.personal-view.com/talks/discussion/5770/metabones-lens-speed-booster

I abandoned the work when there was a rumor of the Speed Booster. It's harder than you think. I say let the professional make them now that they exist.

I'd still be interested to hear your progress. The speedboosters aren't very high magnifications, only 0.7x 0.5 seems like a more powerful reduction.