<p>Shun: Regarding lens speed, fair enough - slow lenses will work in many situations. But they won't work in all situations, and many photographers really do need fast lenses, especially for micro four thirds.</p>
<p>Regarding the 18-35 being designed to clear the reflex mirror, that's certainly true. However, adding a Speed Booster amounts to what is a pretty effective optical re-design, increasing the aperture, increasing the field of view, shortening the physical length, and increasing the sharpness and contrast. The resulting high speed lens takes full advantage of the extra room available in m43 cameras.</p>