Buying HDTVJim Hartsell, Feb. 2007. Major update 1/8/10.
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This is stuff I would have liked to know when I began shopping for a large-screen HDTV. You may or may not agree with me, but at least you will have talking points when you go shopping for one, and can make your own decision.
Flat screen or flat panel? We used to have a 36" CRT (tube-type) TV with a flat screen. Modern HD TVs are flat panel, for their panel-like structure. However, some people call them flat screen.
16:9 vs. 4:3 - The old tube-type TVs had a screen ratio of 4 to 3. If the picture was 30 inches high, the width would be 40 inches. Flat panel HD TVs have a screen ration of 16 to 9, meaning the width is almost twice the height. A 50" 16:9 screen is 43.6" wide, and 24.5" high.
Screen size: Maximum viewing distance is said to be about 2 times the diagonal measure of the 16:9 TV. Our viewing distance is 8 feet (96 inches), so screen size should be 48". We got a 50" - close enough. If you buy a TV too large, you will lose the detail you are buying it for. Don't forget you won't only be watching HD TV. Non-HD is standard definition. If you only watched 1080p Blu-ray on a 1080p TV, viewing distance would probably be the same as the diagonal.
1080i, 720p, 1080p: Our HDTV is 720p. If we were buying one now, I would get 1080p to take advantage of Blu-ray discs. 1080i was highly touted back when we first went shopping. I don't think they had 1080p yet. The "i" stands for "interlaced" where the odd numbered lines are displayed, then the even numbered lines are displayed. 1080i is the same as 480p or 720p, depending on who you talk to. My impression is that "i" (interlaced scan) is old school, and "p" (progressive scan) is better. In progressive scan, all the lines are displayed from top to bottom, and the picture is more stable. 1080p won't be available for a while on cable or satellite. It is only practical if you have a Blu-ray disc player, but satellite and cable offer 1080p for pay-for-view programs. A 720p is 720 pixels high by 1280 pixels wide. A 1080p is 1080 pixels high by 1920 pixels wide.
Pixels: For a given resolution, e.g. 720p/1080p, there are the same number of pixels on the screen no matter what size of screen. The bigger the screen the bigger the pixels. A pixel on our 50" HDTV is slightly over 1/32" square. Our 32" HDTV has the same number of pixels, but a pixel is a little over 1/64" square, half as big. A pixel on a 65" 1080p HDTV is almost 1/32" square.
Screen and pixel size calculator: For my 16:9 HD screen calculator, click here.
Plasma or LCD? For fast motion, plasma tracks it better. I went out planning on LCD because of bad things I heard about plasma, but bought a plasma. When we asked which is better between LCD and plasma, they mentioned reflection off the screen for plasma. Plasma is glass and reflections can be a bother in the daytime. I think it's better to go plasma, and then deal with the reflections. Also with LCD, it isn't as clear as HDTV when you are watching to the side. In July of 2009 at a sports bar, I told my wife that the about-42" TV was an LCD. I asked the owner, and yes, it was. You can tell from the pixelation smudge when something moves.
Fluidity of motion: (Added 12-10-10) The normal refresh rate is 60Hz (60 times per second). To improve "motion blur", higher refresh rates of 120Hz, 240Hz, even 400Hz are offered. Do a Google search for something like "HDTV 60Hz vs 120Hz" to get information. I'm not sure, but I think it only applies to LCD HTDV.
What brand? I went on the internet and Googled for HDTV, quality, rating, plasma, LCD. A Pioneer was rated the best at the time, but too expensive. We got the next one down, a Pioneer. Sony wasn't offering plasma.
Burned out pixels (plasma): A plasma TV is supposed to last 20-30 years. You will be buying a new one before that.
How much to spend? I figured the HDTV will be obsolete in five years. Not worth buying the most expensive.
HDMI: At first there were "composite" cables - yellow for video, red and white for audio. Then came "component" cables - red, green, blue for video, red and white for audio. Now HDMI (High Definition Multimedia Interface) does both video and audio, but the cables are expensive. I couldn't see a difference between a cheap and an expensive HDMI cable, but I wanted to feel like we had the very best connection.
Cable vs. satellite? I heard that cable looses quality going from relay station to relay station. Also that if cable isn't fiber-optic, it is split into 3 signals for transmission, and put back together in the receiver. Cable is part analog and part digital, satellite is all digital. Cable keeps getting more expensive, and goes out frequently. They don't need to change underground cables for satellite HDTV. We chose DIRECTV, a 5-LNB dish for local station HDTV (San Francisco), and an HD-DVR receiver.
Blu-ray player: We recently got a Sony BDP-N460 network player which has an ethernet (LAN) port. Plugged into our high-speed internet router, we can get Netflix movies over the internet for instant viewing. However, downloaded HD movies are very poor quality with our 3 Mbps connection. The pixels look really big. We will need 6-10 Mbps when it becomes available in our area.
Scaling: For a 720 x 1280 screen, video is always displayed at 720 x 1280. If the source is 480 x 704, it is scaled to 720 x 1280. In other words, a 480p pixel is spread over about one and a half 720p pixels. For really bad video source, like a poor VHS tape, it is spread over enough pixels that you can see them.
1366x768 vs. 1280x720: Our 720p 50" HDTV screen is actually 1366 pixels wide by 768 pixels high. This means 1280 x 720 is upscaled to 1366 x 768 and the resulting pixel size is smaller. I suppose this looks better than a 1280 x 720 screen. I have our Blu-ray disc player set to output 1080p since it seems better to me to downscale 1080 to 768 instead of upscale 720 to 768.
On a 4:3 TV, or a 4:3 image in a 16:9 screen, the picture is sometimes a 16:9 image inside the 4:3 frame. Some broadcasts spread this mini-16:9 480i image into the full 16:9 screen. For us, the edges are lost. This could be a difficulty in upscaling the 480i to 1366 x 768. The same thing happens when we zoom a mini-16:9 image to full screen. I don't know what happens on a true 1280 x 720 screen. For more info on 1366x768 vs. 1280x720, see http://hd1080i.blogspot.com/2006/12/1080i-on-1366x768-resolution-problems.html, and Google for 1080i on 1366 x 768.
See http://reviews.cnet.com/720p-vs-1080p-hdtv/ for important information. Also try doing a Google for 720p vs. 1080p. See also http://www.hdtvprimer.com/ISSUES/what_is_ATSC.html for TV formats.
Summing it up: We could replace our 50" 720p with a 75" 1080p and get the same pixel size and viewing distance. But, it would only work if we only watched 1080p programming like Blu-ray discs. As I said above, regular cable/satelite HD won't be 1080p for quite a while. Perhaps a 60" 1080p for the meantime? I'm wondering how it looks when broadcast HD TV at 720p is scaled up to 1080p. It means over half the pixels would have to be created from neighboring pixels.