Optical Mice: The Fall/Winter Collection

Screen Resolution

Unfortunately, the refresh rate is not the only parameter that has to be taken into account. Resolution also plays a part. This is measured in dpi (dots per inch), and expresses the precision of the mouse. In fact, it is more correct to speak of cpi (count per inch) as Agilent Technologies does. Most of the latest optical mice are capable of 400 cpi, meaning that they transmit the coordinates 400 times per inch of movement. This figure implies two things: the precision and physical movement required. Let me explain.

The higher the resolution, the less the mouse needs to be moved in order to transmit the co-ordinates. The phenomenon is magnified, of course, in relation to the screen resolution. It is only on a screen of 1280x1200 pixels or more that the resolutions of the mouse becomes crucial. Microsoft and Saitek display a resolution of 400 cpi but Logitech is aiming to satisfy sharpshooters with 800 cpi. This is in some ways a response to Microsoft's 6000 images a second. After all, optical-mechanical mice such as the Rasor can achieve a precision of 2000 cpi. Logitech claims that at a maximum screen resolution of 1600x1200, you shouldn't be forced to repeat the mouse movement in order to get a response on the screen, although that is what you have to do with mice whose capacity is 800 cpi. Mice with a 400 cpi rating need to be moved further to achieve this. Remember, you can also adjust the speed from the Windows control panel within the limitations of the mouse and that the speed is reduced to 50% by default.

Logitech mice are actually too fast for me at this adjusted speed, and as this interferes with accuracy, I tend to reduce the speed. I'm not really convinced by this argument of the distance covered, but Logitech, like other manufacturers, also claims that the resolution has an effect on the general precision of the mouse and especially on quick movements, which would seem to be reasonable. The problem is that in an optical mouse, the two parameters of resolution and refresh rate are combined. I must confess that this is where my technical know-how runs out and I cannot possibly say whether it is the resolution or the refresh rate that is the most important, or whether it is a combination of the two and if so, in what proportions. If anyone has written a doctorate on the subject, please e-mail us immediately. It is probably reasonable to conclude that the refresh rate ought to improve the response time of the mouse and that the resolution ought to improve precision. This needs practical evaluation with gaming, and for once it should be done subjectively.