Resolution Or Speed?
The real problem is in assessing how these two factors should be combined to arrive at a perfect result. Last year, for instance, Microsoft claimed that speed was all-important, and the standard optical mouse resolution of 400 dpi was quite ample. So they brought out a system with 6000 images per second. Logitech, however, said it was not worth going beyond 2500 images per second, but doubling the resolution to 800 dpi would result in greater precision and responsiveness. At the time, we found it hard to decide which of the two theories worked better in practice, but now our tests have progressed somewhat. Microsoft, without warning, reduced its blue mouse sensors to 2500 images per second. Now, it is decidedly hard to spot any difference in responsiveness compared to 6000 images per second. In fact, it would seem that increasing speed alone beyond a certain limit has very little effect. Resolution, as we have already said, makes the mouse more precise, but also too direct when the resolution is low. This is not really a problem, because you can deal with it by adjusting the cursor speed in the mouse properties. In use, from 1280x1024, 800 cpi turns out to be perfect. You have to lower it a bit, to 1024x786 or less. However, we did not notice any real gain in precision in games like Quake 3. To conclude, 800 cpi is nicer to use in high resolution and maybe improves efficiency a bit because you don't have to move so much when you sweep across the screen, which could be an advantage in games of speed.
The New MX Optical Sensor
Logitech have now decided to confuse the issue a bit more with their new MX sensor developed in conjunction with Agilent Technologies. Let's start with the easiest bit. This is the resolution, which is unchanged at 800 cpi. As we noted, this is a good choice, since it is the one best adapted to high resolutions. On the other hand, instead of images per second, they talk in terms of megapixels per second. I did some browsing through tests in the press, and this new unit is now accepted by everyone who has taken on-board the Logitech marketing spiel about how it is better, more accurate, etc. Here at Tom's Hardware, we are a bit more fussy and would like to know exactly what it means, so we can separate the technology from the marketing. For instance, Logitech also says that the MX mouse can track movement to an acceleration of 10 g, a figure to send you into raptures. It should certainly impress the dude who sees himself at the controls of his F14 fighter plane as it is launched from the aircraft-carrier. But we are not talking about sending the mouse into orbit, we are trying to decide whether this new sensor is genuine progress.