Kenko Tokina announced recently that it'll be making lenses for the Micro Four Thirds standard, and it hasn't taken long to see the first fruits of the collaboration — a 400mm f/8 mirror lens will be released in Japan this Thursday, along with an E-mount version for Sony's NEX system. Kenko Tokina already makes this lens for Canon, Nikon, Sony Alpha, and Pentax SLR mounts, and pricing is expected to be around ¥22,000, or about $290. That's certainly on the cheap side, but this isn't exactly a standard super-telephoto.

This is a mirror lens, meaning that light bounces around inside the barrel rather than passing through curved glass elements. Mirror lenses are usually smaller (this one is only 112mm long), lighter (340g), and much cheaper than their refractive equivalents. On the downside, you're limited to manual focus, the aperture is fixed, and you get unusual ring-shaped bokeh, though you might like the effect. In short, they're far from general purpose lenses, but can be good for shooting stationary, far away things such as landscapes, the moon, or really slow wildlife... just don't forget your tripod.