LensRentals.com - Metabones Magic?

"I think it was pretty obvious that I came armed for battle, ready to slam this product as some marketing overhype. I was wrong less correct than I might have been. The Speed Booster does what they claimed it would do, much to my shock and surprise.

(...) And this is going to be a very useful tool. "



Metabones Speed Booster adapter – full review | EOSHD.com


"Pros

1 stop increase in low light performance
Full frame look – wider field of view, shallower DOF, attractive vignette and light fall off towards corners
Extremely good value for money (look at the saving over buying alternative full frame video solution like Canon 1D X / 1D C)
Protects investment in existing glass
Match glass between full frame camera and Sony E-mount camera on multi-camera shoots
Corrects some optical defects in centre of the frame such as purple fringing and coma
In-camera electronic aperture control for Canon lenses on Sony body
Micro Four Thirds support in pipeline for March (and electronic adapter in June)
Turns Blackmagic Cinema Camera into Super 35mm (matching Alexa)
Every lens now has dual focal length and aperture (use with or without adapter to change crop)
More creative possibilities
Excellent build quality
Very small and light
Tripod mount
Infinity focus tuning built into the adapter and straight forward to use

Cons

Corner and edge sharpness a bit of a struggle with most legacy glass at fast apertures
Soft corners and edges most noticeable at infinity focus with fast apertures or wide open
Speed of auto-focus in need of improvement (painfully slow compared to same lens on a Canon body)
Some lenses are not yet fully supported by the electronics"