brian_caldwell

<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>

<p>Shun: Adapting the Sigma 18-35/1.8 via a Speed Booster is the *only* way to get an f/1.2 zoom for m43. In this case its 12.8-25mm f/1.2 . And the image quality is extremely high even wide open all the way to the corner. There is nothing "native" in the m43 world that is remotely close to it.<br> Andy L: All Canon EF lens mount Metabones m43 Speed Boosters (even the old ones) have been upgraded to have excellent AF performance. Here is an autofocus test with this a Speed Booster + EF version of the Sigma 18-35 using a a slightly older version of the firmware: