Following Logitech's announcement of its new glass-tracking Darkfield mouse sensor, Microsoft countered that only 7 percent of mouse users were interested in mousing on glass. Microsoft also suggested that the remaining 93 percent had already been satisfied by its own BlueTrack sensor, which, unlike Darkfield, is available in mice as low as $40. In those simple terms, Logitech's Darkfield flagship product, the new $99 Performance Mouse MX looks overpriced. The problem is that this ignores the fact that the Performance Mouse MX has more going for it than its newfangled sensor. Microsoft's BlueTrack line offers some versatile, budget-sensitive mice. If you're willing to spend for the best, the Performance Mouse MX delivers not only category-leading technology, but also a refined, if familiar combination of design and features that make it very much worth its higher price.
Up until last year, the laser sensor had established itself as the mouse industry standard, even in high performance gaming mice. While capable of much greater accuracy than the old IR sensor, the common mouse laser is limited in the kinds of surfaces on which it can track. Irregular surfaces, like cloth, or shiny surfaces, like glass, mirrors, and even marble countertops and varnished wood can throw off the reading. Microsoft solved most of those issues with its BlueTrack sensor at the end of 2008. BlueTrack projects a wider, more intense beam of light than traditional laser mice. The only solid surface it can't handle is glass. Here's where Darkfield has its edge.
We tested the Logitech Performance Mouse MX and Microsoft's BlueTrack-powered Explorer Mouse on a fully transparent glass table, and on another glass table with a frosted underside. In both cases, the Logitech mouse maintained its signal while the Microsoft mouse failed. The Logitech mouse also handled all of the surfaces the BlueTrack mouse pioneered, from carpet, to a pants leg, to high-gloss marble. Mirrored surfaces are still too challenging for either mouse.
We can't claim to have tried every variety of glass out there. Your results may vary with safety glass, tinted glass, and other surface treatments and material combinations that find their way into a potential work surface. Still, we're comfortable saying that transparent glass is among the more common potential mousing surfaces out there. And if you've longed to go mouse pad-free on that glass-topped coffee table or desk, Logitech's Darkfield sensor can make that dream a reality. Microsoft's BlueTrack sensor can't.
The sensor technology out of the way, Microsoft's Explorer Mouse becomes a less relevant comparison to the Performance Mouse MX. Both are wireless devices, and both offer battery recharging, but the Explorer Mouse has a much less ambitious take on those features than the Performance Mouse MX.
For its wireless technology, Logitech has brought the Performance Mouse MX into its Unifying USB microreceiver family of devices. The microreceiver itself is a tiny nub of a thing that sticks out less than inch from a typical USB port. As a member of the Unifying family, the Performance Mouse MX can work in conjunction with six other Logitech input devices on the same receiver. Granted that means you're tied to those six devices to take advantage of that efficient receiver ecosystem, which means spending more money on new products to get the full benefit of the Unifying technology. If you're in the market for a complete input device overhaul, we can at least recommend the one Unifying keyboard we've reviewed so far.