That's actually a good point.

There's a widespread and erroneous belief that bigger is always better; in fact, the appropriate size depends on your living room. The rule of thumb is that the width of the television should be no more than half the viewing distance, and no less than a fifth. For matthew330's 36 inch television, that gives the optimal range as being somewhere between 63 inches and 157 inches. That gives us about 5 to 13 feet, but unless you're one of those people who has to sit at the very front or back of the cinema we can probably discard the extremes and say that for most 7 to 10 feet will be the ideal.

Baraka_Guru's 24 inch television, on the other hand (which is equivalent in size to a 720p broadcast on matthew330's television displayed pixel-for-pixel), has an optimal range between 42 inches and 105 inches. Again throwing away the extreme edges, we're probably looking at 5-8 feet being optimal for most folks. If we use the overlap of these two ranges, we can determine that matthew330 should be sitting somewhere between 6 and 8 feet away from his television in order to get the best viewing experience from both resolutions.

If your couch is 10 feet or more away from your couch, I'll concede that a 720p broadcast on a 36" television is probably less than ideal, although being suboptimal does not by any stretch mean unwatchable. Then again, I suppose it comes down to personal preference. Do what makes you happy.

You ought to be able to stretch the 720p broadcasts with no distortion, since it's the same aspect ratio as 1080i.

I don't watch anything worth seeing in SD. I do stretch 4:3 content though. I notice it, I hate it but since I'm already setting too far away from my TV, having 1/4th of the screen as black makes it even smaller and hard to read anything on screen. I really don't care what HGTV looks like anyway.

What formula are you using for that, and what reference screen are you comparing to? I remember seeing one time a calculator, and it said with my living room seating I'd need a 78" to be THX compliant. My setup currently produces a 21 degree viewing arc.

THX is a set of standards based on 10% on how you movies sound and look and 90% on having paid enough money to suck George Lucas' dick. The viewing distances are based on either having a ridiculously big screen or sitting ridiculously close so as to fill as much of the area that both of your eyes can see as possible. This is not practical or enjoyable for most people.

I cannot speak for the home theater market about THX, but when the THX theater certification was done, I find that the theater experience is better. There was a push at one time for Kodak to certify the projector, but that never got anywhere. At the time there were lots of theaters with dimmed bulbs, dirty screens, torn screens, etc.

Is it placebo effect?

I'm not sure, but when I was going to movies in Los Angeles, if I was paying $7 to go to the theater, I was going to go to the best theater I could find. This meant 70MM showings, theaters that spent money on sound systems like 5.1 and going to see the print opening night since the print degrades slowly as it passes through the projector.

I can't remember where I first heard the numbers cited above, to be honest. It's the conclusion that I've come to based on a fair amount of research combined with my own experience.

'Optimal viewing distance' is a highly subjective thing. The range I've given seems to account for the majority of the population.

I do not claim to be the final authority. This is what I've found works for me and most of the people I've discussed the matter with; on the other hand, one should find the experience that one prefers. I suspect I'd be more than happy with a 36" television, but if matthew330 thinks it's unwatchable it'd be a bit conceited of me to tell him he's wrong. My intent was merely to highlight the fact that viewing distance and screen size are highly related variables, and that a perceived problem in viewing experience can be solved by moving the television and/or couch as easily as getting a bigger TV.

I think that optimal.. in relation to TV, is a size that makes people feel that they are well off vs everyone else.

The problem is that a bigger TV requires a better playback device, which requires widescreen, which requires new recordings.