The Metabones Canon EF to Sony NEX Speed Booster allows you to mount any Canon EF-mount lens onto compatible Sony NEX E-mount cameras, such as the Sony FS-700, Sony FS-100, or Sony Alpha NEX- 7. What makes this simple adapter anything but simple is its ability to increase your maximum aperture and make your lens 0.71x wider!
Think of this adapter as being the opposite of a teleconverter. A teleconverter expands the image being projected onto your camera’s sensor, giving us a telephoto crop but also losing light in the process. Teleconverters are popular among nature and outdoor sports photographers who need the extra reach and don’t mind losing a little light to get it. The Metabones Speed Booster, conversely, narrows the image being projected onto the sensor. The image then fills the cropped sensor similarly to how the lens would fill a full frame sensor. The resulting image is still slightly cropped but less so than if you were just shooting with the crop sensor alone and no adapter.
Does a Speed Booster Really Work?
When comparing a Sony video camera using a standard Metabones adapter (which only allows Canon EF lenses to be mounted on Sony NEX cameras with no additional changes) against the Metabones Speed Booster, our video team did notice a significant change in field of view. For example, they put a 50mm EF lens on an E-Mount Sony camera, which has a 1.6x crop factor. This essentially makes that 50mm lens read like an 80mm lens. When using the Speed Booster, that “80mm” lens was “widened” by a factor of 0.71x, which makes it read more like a 56mm lens – nearly full frame!
The compression of light in order to “squeeze” a full image onto a smaller sensor makes the focal length of the lens seem shorter. This, in turn, increases the amount of light actually hitting the sensor. When we attached an EF-mount cine lens (which has manual iris control) onto one of our NEX Sony cameras and manually set the lens to f/4, the camera read it as f/2.8 and the resulting images, indeed, showed an increase in exposure.
But don’t just take our word for it. Check out this brief video that demonstrates some of the crop differences when using this adapter.
Words of Warning about the Metabones Speed Booster
This adapter does not work on everything. You cannot mount it with EF-S lenses nor can you use it on the VG900 when it is in full frame mode. And if this item seems too good to be true, remember that image quality will only be as good as the glass you put between your subject and your sensor. While we noticed no significant changes in image quality in the footage we took with this, adding anything between your camera and your lens is something to keep in mind when shooting as far as the possible hit to quality and sharpness you may experience.