The great response-time hype

This morning ViewSonic sent out a press release announcing that it had changed its mind about its . The LCD now has an official response time of 3 milliseconds (ms) instead of the afore-announced 4ms response time. Why does this matter? Because in the LCD monitor game, the race for the fastest response rate is on, and ViewSonic just pushed itself into the lead by lowering the official response time on the VX924.

Response time refers to the time required for an LCD pixel to change from fully off (black) to fully on (white), then fully off again, and it serves as a rough indicator of how quickly the screen can refresh a video image. However, in most real-life games and videos, pixels are rarely completely on or off. Instead, they mostly cycle between so-called gray states--that is, colors. Generally, switching between gray states is far slower than switching between black and white, so the true refresh time may be a lot slower than the spec indicates. Monitors with very slow response time--somewhere around 30ms--will most likely show ghosting when showing videos and fast-paced video game backgrounds. The problem with this spec, however, is that there's no standard for testing and reporting, so the numbers we hear are usually "gray-to-gray" response time, which is basically half of the monitor's actual response time. But, still, this number usually indicates the monitor's fastest response time, which is probably not what you'll see with daily use.

So, our advice is that you take manufacturers specs, especially response time, with a grain of salt and don't buy into the hype around fastest response times. Your best bet to see how a monitor will actually perform is to test it out. Play fast-moving games and DVDs on your screen and look for trails or ghosting in the images.