HDTV buying guide: Making sense of the specs

Whether you're buying your first HDTV or replacing an older model, you'll find all sorts of new specifications and features to consider when shopping. Some of these apply to both LCD and plasma sets, while others are significant for LED/LCD sets in particular. Here's a quick overview of the different choices and what they may mean for you.

Important specifications for LED/LCD and plasma HDTVs

Resolution: Almost all sets 40 inches or larger have 1080p resolution, which is 1920 by 1080 pixels. A set with 1080p resolution will give you the maximum detail available for almost all HD content. For some smaller HDTV sizes, 1366 by 768 pixels is often a lower-cost choice, but a 720p set has to scale 1080p images down to match its native resolution. This interpolation may introduce imaging artifacts, and the image may not appear quite as sharp or have the depth of the picture on a 1080p set.

While 720p models are available in many sizes as a lower-cost option, they remain prevalent in the 40-inches-or-smaller category. If you're shopping for a small HDTV, expect to pay about a 20 to 25 percent premium (as of this writing) for a 1080p set over a 720p set. All else being equal, we recommend that you pick a 1080p model, which will better match much of the content you can now get from broadcast, streaming, and satellite services, and will match the native resolution of a Blu-ray Disc player.

Contrast: This spec (also known as "contrast ratio") refers to the difference between the darkest images and the lightest images that a screen can produce; in general, it is determined by how dark the blacks are. Contrast is probably the most important factor in determining image quality after resolution. If the blacks are gray and the contrast is lower, the whole image can look washed out. If the blacks are deep and strong, however, the image will look sharper and the colors will pop.

Unfortunately, manufacturers' methods for measuring and specifying contrast are almost useless for helping you predict how the screen will look. Manufacturers use full-screen measurements, all black and all white, in a darkened room. An all-black or all-white screen is not what people watch, and in computer terms it conveys precisely zero bits of information. When you have actual content on the screen, you get internal reflections, ambient lighting effects, and other optical crosstalk that results in the light from one section of an image affecting the light levels of another. Basically, pay attention to the contrast with your eyes, but don't worry about the reported "contrast ratio" spec.

Internet connectivity: These days, most big-brand HDTVs offer the ability to connect to your home network's router--either through a cable or wirelessly--so that you can view content stored on the computers on your network and access content from the Internet if you have broadband service. Different sets have different features, such as Amazon, Netflix, or YouTube, so if you want a particular service, make sure that it's included before you commit to an HDTV--or find a Blu-ray player or streaming set-top box that has the service you want. Manufacturers are adding new services all the time, even to their existing models, so it pays to get the latest information. Note that if you use a wireless connection, 802.11n will give you the fastest performance.

3D support: By now, each of the major manufacturers has a fairly wide range of 3D TVs on the market at various price points. For most prospective TV buyers, 3D isn't a necessity quite yet simply because there isn't enough 3D content out there yet. That said, If you're intrigued by ESPN 3D, building up your 3D Blu-ray collection, or simply want to future-proof your TV, there's a few things you should know about 3D before you pull out your credit card.

• Active shutter or passive 3D? There are currently two types of 3D glasses technology found in HDTVs right now, "Active shutter" and "polarized" or "passive". Active-shutter glasses are more expensive (often about $150/pair) and a bit heavier, since they're actually two small LCD screens that alternately dim each "lens" in sync with the TV by way of an infrared emitter so you can see a 3D image. Polarized glasses, on the other hand, are the kind you'll find in 3D movie theaters--in fact, some TVs will even work with the exact same glasses from the theater (which you were supposed to return, by the way). They're cheaper, lighter, and easier to wear, but they technically don't provide as high-quality an image since each lens blocks out some of the light to create the 3D image. So far, however, we haven't seen a significant quality difference between the two 3D technologies--read Active vs. Passive 3D and Do Passive 3D TVs Sacrifice Quality for Comfort? for more information.
• What are you going to watch? There isn't much 3D video out there at the moment. Your cable provider might have a channel or two (typically ESPN 3D and a 3D video rental channel), but otherwise you're pretty much limited to what's on the 3D Blu-ray market. Also, keep in mind that 3D TV manufacturers are still scooping up hot 3D Blu-ray movies for their 3D "starter kit" bundles, which means that you can't buy the 3D version of Avatar on Blu-ray without shelling out $230 or so for the two pairs of Panasonic 3D glasses--which won't work with anything but a Panasonic 3D TV.
• Don't wait for glasses-free 3D TV. While we've seen some pretty promising prototypes over the years, the fact is that right now, glasses-free 3D is far too expensive and limited to implement in consumer-friendly HDTVs. If you're pondering getting a 3D TV, don't worry about glasses-free 3D TVs coming in a year or two--they're looking like they're at least 5 years, maybe up to 10 years away.
• Yes, you can watch 2D TV. The only difference between a 2D and 3D TV is that the 3D model has a display mode that lets you use the included 3D glasses with the TV. You don't need to watch everything with the 3D glasses, though some TVs do support 2D-to-3D upconverting if you want to watch everything in 3D. (The upconverting isn't particularly impressive yet, though.)