We’re thinking of going HD and let me just say that it is a terrible thing to do. Actually going HD may be fine, but thinking of it makes my head hurt. I asked some colleagues and friends for input and got a lot of info- but one thing kept coming through: you have to stand there and look at the darn things to compare them and you won’t know if you like it in your room until it is there.  So without further ado, here is what I’ve learned thus far…

Sizes

Regular TVs, what are now called SDTV (for subpar-definition TV) have a 4:3 aspect ratio. This golden ratio gives 3″ of height for every 5″ of diagonal. For some reason TVs are always measured diagonally so our 35″ SDTV has a picture that is about 21″ high. This is important because HDTVs are widescreen using the big screen aspect ratio of 16:9. Using the pythagorean theorem we can deduce that every 18.3575597506″ diagonal gives us 9″ of height. Using some other geometric law we can see that to get 21″ of height I need to get a (21/9 x 18.4) 43″ HDTV. Of course the standard sizes seem to be 42″ and 47″ so we’ll probably go with 47″. 

See, geometry does come in handy later in life. 

sdtvtohdtvequiv.jpg

Resolutions

Standard definition here in the US gives us about 480 lines of vertical resolution (http://en.wikipedia.org/wiki/High-definition_television). HDTV comes in a few different flavors: 480, 720 and 1080 lines of resolution. The more lines, the more detail and the sharper a larger TV can be. There are also two letters that can follow the resolution number: p and i. You want p if possible. The common resolutions that you will see in most HDTVs as of early 2008 are 720p, 1080i, and 1080p. 

If we get a 47″ HDTV then the TV will have a screen about 23″ high. At 720 there will be about 31 lines per inch and 1080 will have about 47 lines per inch. 

Technology

The market gets a lot broader when you start looking at the various technologies that display the picture- be it LCD, plasma, or one of the projection systems. The general consensus is that plasmas have better blacks, but some of the new LCDs are supposed to close that gap. The projection systems tend to be cheaper, but to my eyes they are dimmer than the others. 

Also worth noting is that plasma TVs are apparently gas guzzlers and some countries have groups lobbying for their removal from the market. I am a fan of the environment so I think that the plasma is less desirable for that fact alone. 

Other features

Apparently I want a TV that can do 120Hz refresh – which helps to narrow the field. 

Also important are the AV inputs. We’ll certainly get at least 2 HDMI, but 3 would be better. I’d like DVI or VGA input for a computer and some component inputs would be welcome (not sure how many I expect to use). 

As we have DirecTV we’re not concerned about tuning in HDTV, but if you have cable then there are other things to think about like CableCards and over the air broadcasts. We just have to buy a new dish and receiver. 

TiVo

I don’t think that TV is worth having if you don’t have a TiVo. I’ll have to get an HD TiVo, but apparently the HD TiVo’s don’t worth with the DirecTV HD receiver. DirecTV’s original DVR was pretty universally panned but the word is that their HD DVR is better. I’ll have to look into the DirecTV HD DVR a little more. 

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