3-D TV Q-and-A

Q: Do I have to wear glasses to get the 3-D effect?

A: Yes. And the glasses question became more complicated recently, when several manufacturers announced sets using a new 3-D TV format.

In 2010, all 3-D sets worked with what's called active shutter glasses. The two images required for the 3-D effect are shown on screen one after the other, very quickly. The glasses black out each eye in sequence, synchronized to the changing picture, so your right eye sees only the right-eye image and vice versa. Unfortunately, these glasses are expensive (around $150 each), can cause a flickering effect and require recharging.

If you've been to a 3-D movie lately, you were given passive glasses that use polarizing filters to separate out the right and left images. Now 3-D TVs using this passive system are headed to market, bringing the price of glasses down to about $10, making them lighter and more comfortable, and eliminating the charging process. There is a picture quality trade-off, though — you get only half as much vertical resolution using the passive glasses display. How much difference will this make? So far, only one television using passive technology has shipped, from Vizio, and reviewers were unimpressed.

And just to add another layer of complexity to the shopping process, some tech companies are promising full-resolution passive-glasses sets later this year.

By the way, you may have heard about 3-D TV you can watch without glasses. There were a few technology demos of these sets at the Consumer Electronics Show in January, but no actual product announcements. What we saw was interesting but clearly not ready for consumers, since these sets require you to sit in specific spots to get the 3-D effect.