Field Trip Into HDTV

I don't usually spend a great deal of time watching TV, but ever since Dell loaned me a 42-inch high-definition plasma TV, I find myself almost looking for excuses to plop down on the couch to catch a movie or a show.

The TV, which Dell sells online for a starting price of $2,799, is only 3.3 inches thick, making it thin enough to hang on a wall with an optional mounting kit. Unlike some of the older flat screen models, it has a built-in tuner. I never actually tested the tuner because I've been getting my signal from Dish Network, which supplied me with a high definition satellite receiver that plugs directly into the Dell screen. Together, they provide a stunning picture, though I'm told that cable TV signals can be just as good as can over the air signals, if you live close enough to a TV station that broadcasts in hi-def.

Like all high definition TVs, the Dell displays programs in wide screen, which means that HD programs have about the same aspect ratio (16 by 9) as movie theater screens. Standard TVs have an aspect radio of 4 by 3, which means that the screen is only 33% wider than it is high. With 16 by 9, the screen is 78% wider than it is high, similar to a movie theater screen. Movies look a lot more like the director intended them to be and TV programs designed for HD look great as well.

But there's more to HDTV than the shape of the screen. The biggest deal is the resolution. The old styles TVs (called NTSC) in theory have 525 horizontal scan lines but in practice TV uses only 480 lines.
With 720 pixels per line, the TV has a resolution of 345,600 pixels.

There are actually two different standards for HDTV: 1080i and 720p. 1080i has a resolution of 1,920 by 1,080. At first glance you would think that the 1080i resolution is a lot better, but it isn't necessarily since the 720p uses progressive scan, drawing an entire image at once, which leads to a smoother appearance.

Specifications aside, at the end of the day what matters is what you see on the screen. In that regard, I was very impressed. Color saturation is excellent and blacks - though not perfect - were quite good. The picture looks awesome when sitting directly in front of the TV but quite good when looking at it from the side as well. It also looks good when the lights are on.

The sleek black backlit remote control has a classy feel to it, as does the overall look of the TV.

There are has been considerable discussion about the life span of plasma TVs. Like CRTs, plasma runs the risk of burn in. That can happen if an image - such as a logo - is displayed on the screen for an extensive period of time.

Another issue is the lifetime of the screen. Early generation plasma TVs did have relatively short life times. Dell claims that its plasma screens have a "half-life" of 30,000 hours. What that means, according to Dell TV product manager, Carolyn Lowe, "is from the day you buy it, if you watch TV for eight hours a day, it will be about eight years before you get to the half-life meaning your TV will be half as bright as the day you plugged it in." To avoid burn-in, Dell uses pixel-shifting technology, which moves the pixels around very slightly, so they don't remain in the place for an extended period of time.

Before you run out and buy any high definition TV, consider the alternatives. In addition to plasma, there are numerous other technologies to consider including various flavors of rear screen projection, LCD and even old-fashion CRT that have been updated with high definition resolution.

If size matters, rear projection TVs tend to give you more bang for the buck. They're not as thin as plasmas, but they still have a flat screen and, depending on the model, can look quite sharp. CRTs are typically your least expensive option and today's hi-definition CRTs can look great, though they do take up a lot more space than flat panel TVs.