Following Logitech's announcement of its glass-tracking Darkfield mouse sensor, Microsoft countered that only seven per cent of users are interested in mousing on glass. Microsoft also suggested that the remaining 93 per cent had already been satisfied by its own BlueTrack sensor, which, unlike Darkfield, is available in mice as cheap as £25. In terms of money, therefore, Logitech's Darkfield flagship product, the £80 Performance Mouse MX, looks overpriced.
But the Performance Mouse MX has more going for it than its newfangled sensor. If you're willing to splash out, 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 industry standard, even in high-performance gaming mice. While capable of much greater accuracy than the old infrared 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, marble 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. That's where Darkfield has its edge.
We tested the 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 that the Microsoft model did, including carpet, a trouser leg and 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 or tinted glass, for example. Still, we're comfortable in saying that transparent glass is the type that you're most likely to use as a work surface. If you've longed to go mouse-pad-free on a glass-topped coffee table or desk, Logitech's Darkfield sensor can make that dream a reality. Microsoft's BlueTrack sensor can't.
With sensor technology out of the way, it becomes less relevant to compare the Explorer Mouse to the Performance Mouse MX. Both are wireless devices, and both offer rechargeable batteries, but the Explorer Mouse has a much less ambitious take on those features than the Performance Mouse MX.
In terms of wireless technology, Logitech has brought the Performance Mouse MX into its Unifying USB receiver family of devices. The USB receiver 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 compatible Logitech input devices on the same receiver.
For its part, Microsoft's mouse relies on a standard USB receiver that works only with the mouse it was purchased with. The receiver does snap into the body of the mouse for easy storage, but the Logitech mouse's USB receiver is so small you don't need to take it out of the USB port to begin with.
The Performance Mouse MX also offers an advantage in terms of its recharging system. Rather than providing a recharging station, such as Logitech has used in the past, the company has simply added a mini-USB input to the front of the mouse. Connect the mouse to a powered USB port via the included cable and you can recharge with no usability downtime.