The decision most people associate with HDTV is the selection of the display. It’s easy to understand; it’s the most visible and glamorous part of HDTV because magazines and Websites are generally silent. They show appealing photos but seldom speak to you.

I’m going to speak to you. It’s based on research, experience and, of course, is my sole opinion.

The selection of your HDTV display depends on more things than you might suspect at first. Aside from your feelings about thin, flat panels versus the thicker rear projection systems, there are also considerations for the physical aspects of your dwelling, the kind of viewing you do, how far you sit from the TV, and your budget. For a good home HDTV system, the TV itself is likely to be only about half your total expenditure. So if you over-invest on the TV, you’ll find yourself in trouble when it comes to funding the other components.

HDTV Display Size, Round #1

The first thing to consider is the size of your current TV, which has an aspect ratio of 4:3. In moving to a 16:9 screen, you probably won’t be happy unless the vertical dimension of the new HDTV is larger than what you have now. For example, if your current TV is a 32-inch diagonal CRT, the vertical dimension will be 0.60 x 32 = 19 inches. For an HDTV, the vertical dimension is 0.50 of the diagonal size, so in this case, the minimum diagonal size you’ll want for a new HDTV will be 38 inches. And so on for your size.

HDTV Display Size, Round #2

It is generally recognized that, for an immersive experience, the HDTV screen should subtend an angle of about 30 degrees, horizontally. A rough rule of thumb then is that the TV’s diagonal measurement should be a little bit more than half of eye-to-screen distance. (Actually, it’s 63%). For example, if you sit 8 feet from the screen, you’ll want at least a (96 x 0.63 = ) 60 inch HDTV. If you’re willing to settle for 25 degrees, the minimum I would say, that drops to 50%, or 48 inches. The difference in price rises dramatically between these two extremes, so some informal testing with your current TV and a tape measure will help a lot.

Of course, as you know from movie theaters, some people like to sit way up front, some in the back. Even so, if you’re serious about HDTV, you’ll want to shoot for that 30 degree rule.

HDTV Display Size, Round #3

If you study enough HDTV, you’ll find articles that discuss the relationship between the sitting distance, pixel size, and the resolution of the human eye. The question is, if the TV is small enough, or you sit far enough away, can your eye really exploit the resolution of a 1080p screen?

However, the question is quickly becoming moot because even the mainstream Plasma TVs have moved to 1080p. A few years ago, you might have needed to ask whether you can see the difference between a 720p and 1080p TV in order to justify the cost. In 2007, however, native 720p TVs are fading. Even so, if you’d like to read about it, Carlton Bale has published a nice discussion with charts.

HDTV Display Size, Round #4

Finally, in a fashion similar to how the price goes up with display size, so does the weight. It’s not a square-cube law, but it’s still something to be concerned about. A 32-inch LCD will weight about 25 lbs. Not a problem. However, a 52-inch LCD weights about 70 lbs, a 50-inch Plasma about 100 lbs, and a 60-inch rear projection system also about 100 lbs. Multiply by 1.5 to get the estimated shipping weight.

If you don’t plan to have the HDTV delivered and installed by a professional, you’ll be confronted with the prospect of you and friends grappling with a large, awkward box. If you live on the third floor of an apartment, with no elevator, you’ll be faced with the unpleasant prospect of either carrying it up the stairs in its shipping container to protect it or removing it from the shipping carton and risking a the collision of the screen with a hand rail destroying your new HDTV.

However, if you own a home in the suburbs, and your front porch is a roughly drive-way level, you might be able to talk the delivery guy into bringing the box just a little further to your front door and foyer. There, you and an assistant can deal with it better. That is, unless it’s destined to go into the basement, down stairs with a sharp turn. Better to either have the system installed, or think about a practical 25 lb, 32-inch LCD HDTV for the basement.

The Display size, Bottom Line

Let’s say you’re willing to spend about $2,000 on the display. That’s a good target price for a beginner system. That will get you the low ends, but still 1080p, of a 55-inch rear projection, 50-inch Plasma, or 42-inch LCD TV, very roughly. Those TVs can be handled safely by two adult men. (Your mileage may vary.) Such displays will have a vertical size likely bigger than your current SDTV, and you’ll be sitting about 8 feet away.

The BIG Choice. LCD, Plasma or Rear Projection

A few years ago, rear projection was the only way to go. The screens were big for their cost, and Liquid Crystal on Silicon (LCoS) was a very good choice -- especially for those who wanted to stay away from a DLP TV with its color wheel rotating at 14,400 rpm. (Some DLPs have now moved to 3-color LED lighting, which also eliminates the need for an expensive replacement lamp.) LCoS and DLP/LED rear projection TVs are excellent choices, and if you want to maximize screen size, minimize cost, and don’t care about the bulk, they’re a good choice. Just not quite so fashionably thin.

My choice would be a LED driven DLP. They have no moving parts (except the micro mirrors) and no lamp to replace. Samsung, for example, makes them, and they have excellent black levels. They also have the added advantage of being capable of true 3-D imaging with electronically controlled shutters in goggles. Sony, as of this writing, continues to use a lamp for their LCoS ("SXRD") systems, and I decided I didn’t want to go down the road of $250 replacement lamps.

As of 2007, however, the flat panel displays have come a long way. A very long way. LCD technology used to be constrained by the fact that thinner liquid crystals didn’t have the black levels desired, but had faster response times. Making the liquid crystal layer thicker gave a better black level, but the response time was slower. (The ratio of the brightest level to the darkest level is called the contrast ratio. It can be a dubious marketing term if mis-used.)

Tweaking the LCD technology to avoid that bad engineering compromise between pixel response time and black level plus improvements such as LED backlighting and/or 120 Hz refresh have brought LCD displays to the point where a semi-purist would no longer retch at the idea of a large screen LCD.

Similarly, Plasma displays have also come a long way. Panasonic is the world leader in Plasma sales, and their displays are in their 10th generation. Pixel shifters and better design and construction have reduced the burn-in issues, but one must still be careful. Special anti-glare coatings make Plasmas the equal of LCD. Screen brightness is on par with LCD. Finally, the faint buzzing caused by acoustic coupling between the plasma and glass plates has been eliminated below 9,000 feet above sea level. The latest 10th generation Panasonic Plasmas are rated at 100,000 hours to half brightness, so that bugaboo is gone. Pioneer also makes excellent Plasma displays, the Elite series. So everything you thought you knew about Plasmas is out of date.

The one area where Plasmas excel is in the apparent richness of the light. It seems almost three dimensional and most closely equals the qualities of the older CRTs. LCDs, on the other hand, can still seem a bit two dimensional and flat to some viewers. They do to me.

So how to choose?

It really depends on your viewing habits. If you are a TV fanatic and most of your viewing will be over-the-air/cable/satellite HD at 1.78:1, it’s unlikely you’ll need to worry about burn in, so Plasma is a very good choice. An occasional 2.35:1 movie, with letterboxing, certainly after the first 200 hours of use, for a 2 hour movie won’t develop any burn in. The new Plasmas also have circuitry that detects long periods of letterboxing and will alert you.

On the other hand, if you are a movie fanatic, have a great collection of DVDs, use Netflix, etc, you’ll probably want to think about an LCD display which has zero burn in issues. You’ll never have to worry about letterbboxing (top and bottom) or pillars (left and right) for anything you watch. Also, you’ll want to select an LCD that’s not only 1080p, like the new Plasmas, but also has an option for 24 fps input or variable screen refresh rates that are multiples of 24 Hz. For example 72 or 120 Hz. HDTVs that have 1080p/24 input, in addition to the standard 1080p/60, will have a more pleasing picture for movies (especially fast action) because they can accept the movie’s native 24 fps without having to resort to what’s called 2-3 pulldown (sometimes called 3:2 pulldown).

HDTVs that don’t have a 24 fps input must resort to a trick, telecine 2-3 pulldown, which (irregularly) maps those 24 frames each second to 60 frames per second. The process introduces an effect called "judder" that’s most noticeable in fast motion. Avoiding the 2-3 pulldown is a nit for most, a must for the purist.

Rear projection TVs constitute only a few percent of total sales. I think they may eventually disappear. In the U.S., there is a strong movement to flat panels, and four out of five thin TVs sold today are LCDs. That may be due to the fact that myths still persist about Plasmas. My advice is to take a close look at both and decide for yourself when your viewing habits are taken into account.

So here’s the verdict. If your family is more oriented towards movies, either from broadcast or disc, and you’re thinking about getting a Blu-ray or HD DVD player with 1080p/24 output, then I’d go with the biggest LCD (with LED backlighting and 24 fps input) you can afford.* I’ve seen LCDs with LED backlighting, and they use a grid of LEDs that can be individually and rapidly turned on/off as needed to obtain astounding black levels. Go for that if you can afford it and expect to pay closer to $3,000+ with a good discount for a 42-inch. LCDs with Cold Cathode Fluorescent (CCFL) backlights and perhaps even 2-3 pulldown will be, I believe, obsolete in 2008. However, you’ll see a lot of them for sale this Christmas, and your money will go farther towards a bigger screen. TANSTAAFL.

On the other hand, if you only watch an occasional movie, plan to ride out the HD disc format war, and want to generally enjoy HD via antenna, cable or satellite, then take a close look at Plasmas. Their natural, deep looking picture is hard to beat in my opinion. Just be careful. Plasmas have only recently moved to 1080p, and you may find some too-good-to-be-true, fire sale prices on 720p/60 Plasmas out there. For example, some older generation 42-inch 720p/60 Plasmas can be had (er, unloaded) for around US$1000. However, a good Pioneer or Panasonic 50-inch 1080p/60 plasma will still cost about $2500. Those with 1080p/24 capability will be more.

There are many, many more technical details, but this is all I have room for. What I’ve discussed here should get off to a good start. Next time: paying attention to HDTV audio.

* Note that you’ll still have to set aside funds for, possibly, an A/V receiver with HDMI switching, perhaps additional speakers and maybe an HD DVR.

Math notes:

For a rectangular NTSC TV with 4:3 aspect ratio, display width x, height y, and diagonal size z, then x = 0.80z and y = 0.60z.

For a rectangular ATSC TV with 16:9 aspect ratio, display width x, height y, and diagonal size z, then x = 0.87z and y = 0.50z.

If D is eye-to-TV distance, d is diagonal measurement of TV, and theta is desired horizontal angular extent, then D/d = 0.44/ tan (theta/2)

Here are the links to all six articles in the series.

Nov 7th:The Fireside Guide: Moving to High Definition, Introduction

Nov 13th: The Fireside Guide: Moving to High Definition, Display Selection

Nov 16th: The Fireside Guide: Moving to High Definition, Audio Selection

Nov 29th: The Fireside Guide: Moving to High Definition, Source Selection

Dec 6th: The Fireside Guide: Moving to High Definition, Installation

Dec 14th: The Fireside Guide: Moving to High Definition, Sample Systems