What Aspet Ration for HD Network Shows

A true beginners question. I just purchased a Vizio 50" Plasma HDTV and am delightedw ith the set and more delighted at the price.

Anyway, what aspect ratio do the major networks use for their HD programming?
Zoom and 16:9 seem to stretch the picture. Are all network shows in 4:3 aspect ratio only??

All network format I've seem that's made specifically for HDTV, such as "Smallville" is is 16:9,

That's not to say that they can't show a SD program on their HD stations, in which case my TV is set to show them in 4:3. Homey don't do da stretch thing given a choice. It makes them look short and squat.

Now, I've seen some stations pull a sneaky. They will take a 4:3 program and somehow manage to "stretch" only the extreme right and left side of the picture so it initially appears to be a 16:9 program but, after a while, you start to notice that the proportions ofthe prople change as they exit and enter the picture from off screen. IMNSHO. that sucks.

At this point, I'd venture the guess that at least 80% of hi def broadcasts are in the specified 16x9 (1.78:1) aspect ratio, though some of them still preserve the 4:3 (1.33:1) aspect ratio of the good old days. The Vizio should have at least one option for stretching 4:3 material to fit the screen, but it may not work with actual high-resolution programming, since in this case, the black bars are actually part of the broadcast, not generated by the TV. I suspect that what you're zooming isn't truly hi def. Only certain stations from the cable company qualify, and they're grouped within a certain number range (e.g., 800-900). A widescreen hi def picture is always in 16x9, which fits the screen perfectly, no zoom of any kind possible or warranted. Certain films shown on premium HD stations might have aspect ratios that exceed the HD standard, such as 2.35:1 (think Gladiator and other "big" movies). Usually, the sources downsize these movies to 16x9; a scarce few might sneak through at their native ratios, leaving black bars at the top and bottom of the screen, though this phenomenon is far more common with DVDs. As with 4:3 programming on HD channels (which blanks the screen at the sides), unless a TV has the relatively new ability to eliminate these source-created black bars, they are incorrigible. A few HD stations have been known occasionally to upconvert standard-def material to hi-def resolutions, stretching it improperly to 16x9 anamorphically (TNT comes to mind), making everything look chubby and malformed. But this is an anomaly. Basically, when viewers receive hi-def broadcasts, they simply leave them alone.

nicely said Ed