Maybe free lunch exists after all. The Metabones Speed Booster is a new adapter for Micro 4/3 and Sony NEX that is designed to reduce the focal length of an adapted SLR lens while
increasing the speed of the lens. This type of adapter, called a focal reducer or telecompressor, is essentially the opposite of a teleconverter.
The idea is not new. For example, the very early
Nikon E series DSLR, co-developed with Fuji, used a 4X focal reducer to get the full angle of view and light collecting power of full frame lenses condensed to a 2/3" sensor, and Kodak has a
1994 patent describing a device similar to the Metabones Speed Booster.
To date, no one has been able to design a general use focal reducer that will work with fast lenses while effectively addressing optical aberrations, especially spherical aberration and field curvature. According to the
white paper, the engineers behind the Metabones Speed Booster were able to create a focal reducer that accomplishes these goals by designing specifically for mirrorless cameras.
The Metabones Speed Booster reduces the focal length of an adapted lens to 0.71X, where X is the original focal lengh of the lens. At the same time, it increases the lens speed (virtual aperture relative to focal length) by one full stop. Thus a 35mm f/1.4 SLR lens fitted to the Speed Booster physically becomes a 25mm* f/1.0 lens.
*50mm equivalent angle of view on MFT, 38mm equivalent AOV on NEX
For more information, read the white paper:
http://www.metabones.com/images/meta...te%20Paper.pdf
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Metabones Speed Booster - New Focal Reducer Makes Lenses Faster, Wider, and Sharper
