How are widescreen TVs measured?
November 9, 2004 7:04 AM   Subscribe

If I get a 27 inch TV, the measurement is corner to corner, right? How are widescreen tvs measured? What's the difference between a 30 inch regular tv and a 30 inch widescreen?
posted by mkn to Technology (8 answers total)
They're both corner to corner. If you do the math on this, it sucks.

30 inch widescreen = 26" x 15" = 390 sq in
30 inch regular = 24" x 18" = 432 sq in

On a widescreen image, you gain 2" in width by switching. The price increase is generally not worth it.
posted by smackfu at 7:20 AM on November 9, 2004

But the point of widescreen tvs is to watch movies that are widescreen. So you'd have to subtract the square inches from your regular tv that just display the black bars at the top and bottom.
posted by GeekAnimator at 7:45 AM on November 9, 2004

Yep. You have to buy a much larger widescreen tv if you want similar picture area. Oh well. Bigger is always better when it comes to TVs. :-)
posted by rglasmann at 8:17 AM on November 9, 2004

Response by poster: Yeah, that's what I figured. I realize that if you watch widescreen on regular tv, you lose the inches on the top and bottom -- but when you watch non-widescreen stuff on a widescreen tv, you lose the inches on the side, so it more or less cancels out.

The measurement is still kind of deceptive in this regard, though. Oh well.
posted by mkn at 9:21 AM on November 9, 2004

Subtracting the black bars on a 4:3 screen to make it 16:9 gives an effective screen size of 24" x 13.5" = 324 sq. in. So if you're planning to watch mostly movies or widescreen HDTV it's probably worth it to get a widescreen TV.
posted by stopgap at 9:33 AM on November 9, 2004

A 27" regular TV has a picture about as tall as a 34" widescreen, but the widescreen is wider.

A 40" regular tv has a picture about as wide as a 34" widescreen, but the regular one is taller.
posted by ROU_Xenophobe at 9:43 AM on November 9, 2004

Think of it this way: if you want a screen that's the same height as your current 4:3 TV but you want it wider, it's going to increase the diagonal measurement.

As for the black bars: when you watch 4:3 (TV-shaped) stuff on a widescreen TV you don't have to lose anything. In addition to zooming for a horizontal fit you can have a vertical fit by doing the widescreen equivalent of letterboxing (with black bars on the left and right) or you can stretch the image to fit in both dimensions, but distorted. Choose your poison.

As long as we watch stuff that's in different formats we're going to be wasting some of the capability of any viewing device we use if we want to get the best image. Don't forget the widescreen movies are hardly of a fixed aspect ratio. Plenty of them are wider than 16:9 so you still have to letterbox or stretch the image (and some of them in fact are 4:3, fitting a conventional TV perfectly).

If you're investing in a TV for watching widescreen DVDs or for watching 16:9 HDTV content then a widescreen TV definitely makes sense. If you mainly watch TV, or if you watch your DVDs in full screen mode (why do people do this?) then you're better off with a 4:3 model for now.
posted by Songdog at 10:54 AM on November 9, 2004

It all depends on the aspect ratio of what you're watching. The most common being 1.33:1, 1.85:1 and 2.35:1. For 30-inch regular and widescreen TVs:

...if the source is 1.33:1 (4:3, "normal" SDTV)
regular = 30-inch image
widescreen = 25-inch image

...if the source is 1.85:1 (16:9, HDTV, Narrow Panavision)
regular = 27-inch image
widescreen = 30-inch image

...if the source is 2.35:1 (Wide Panavision)
regular = 26-inch image
widescreen = 28-inch image

Also, there's a problem faced by owners of some widescreen TVs. Several shows such as ER are 1.85:1 but if you're watching an SDTV source, black bars are added top and bottom to convert it to a standard 1.33:1 signal (non-anamorphic widescreen). On a widescreen TV you end up with these bars plus the black sidebars generated by the TV. This results in a 23-inch image floating in the middle of a 30-inch screen. If this is a concern, look for a TV with a zoom function that will blow up the centre of the screen and eliminate all these black bars.

I assume those that refuse (or are unable) to update their 4:3 TVs will have the same problem once broadcasters switch to a native 16:9 digital signal. Reruns of 1.33:1 programs will have black bars added to the sides in addition to the letterboxing added by the set-top digital tuner/16:9->4:3 converter. This will result in a 21.5-inch image floating in a sea of black. Future 4:3 TVs may include a zoom function, but I don't know of any current models that do.

On preview, what Songdog said.
posted by Monk at 11:22 AM on November 9, 2004

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