Compatible Cameras: Sony FS7/ FS5/ a6300/ a6000, Sony a7S/ a7S MkII/ a7R/ a7R MkII in APS-C mode
This Speed Booster version optically reduces the lenses image circle so that the field of view is the same as it would be on a full frame 35mm stills chip camera. EG: a 25mm lens will have the same field of view on a FS7 as it would on a Canon 5D using this adaptor.
It also increases the lenses speed by 1 stop, hence the name.
NB: You can use the speed booster on a Sony A7s but it will switch the camera to APS-C crop sensor mode as camera itself is Full Frame.