Axiom Home Page Forums General Discussion Home Theater Screen size -- how big is too big ?

I thought about building a HTPC, but the thought of fighting with yet one more stinking computer killed the idea. Between my home PC, my work PC, my personal laptop and my work laptop, I just don’t think I can deal with one more. Computers are great until they decide to misbehave, then I’m totally hosed because I don’t have the patience to screw with them.

The CIH thing is way cool, but way expensive too. $1500 and up for a lens, anther $2000 and up for a VP or buy a different projector that will stretch the image, then the masking system. My hour and a half or so look in awe at my wrinkled bed sheet should tie me over for a while. The image that 900 has over my 46” hd1080 mits TV is unbelievable. I can’t wait to see it on a real screen, and with sound.

I find that about 84 X 36" is the right size for the 2.35 stuff and 72 X 40 is about right for 16.9. But if I keep the height the same at 40", the 2.35 image is too big for me. I never would have guessed that picking the screen size would be this difficult.

Dave,

The whole room is a very dark garnet red in an eggshell finish. The front wall is solid and the rest of the room is what I call “Mike’s Mistake”. I tried to do some faux coloring with garbage bags and screwed it up royally. Ended up painting over it a couple times with the red to end up with something quite unusual. The image on the red wall didn’t show up at all. The black bars are non-existent. I could very easily zoom the 2.35 stuff if I make the screen wider and not even notice them, which is easy enough but I don’t want to have to shift the lens and zoom each time. So it’s either zoom and shift or zoom half way and mask the bottom.

Apparently the TheaterTek software can shift the 2.35 image up and down within the larger 16:9 frame, so you should be able to get rid of the need to shift that way.

I find computers work pretty well if you don't mess with them. I'm hoping that extends to my hypothetical HTPC

I read an article in Digital Tv and sound a few months ago. It said to find the optimal viewing distance for a 16:9 image is 3400*(image height in inches)/(vertical resolution). For example if you have a 50 TV with 1280 by 768 resolution then the vertical height is 24.5 inches. So the viewing distance would be 3400*24.5/768 = 108.8 inches. If the Tv were 1080p the viewing distance would be about 77 inches. If the TV were 480p the viewing distance would be 173 inches. Apparently this is the distance to sit to take advantage of the higher resolution. So if you sit 77 inches away from that 1080p display it wouldn't look any better than if it were 768p.

So here is where things get interesting. Within the next few years I imagine many people will have dvd's which are in 480p and high def dvd's in either 720p or 1080p. So what viewing distance do you set up? Do you set up a front row at the right distance for 1080p and the back row for 720p? Or just have one row and simply zoom in and out. I imagine once you go 1080p you won't want anything less.

- Nick

For my setup (16:9 image is 48" high, projector is 720p native) that means a 226" viewing distance, or about 19 feet. Was this an article in "Binocular Life" or something ?

For dealing with varying resolutions, my strategy is to adjust the system and seating positions for the highest resolution images then complain loudly when watching lower quality material. It seems to handle the wide range of DVD recording quality; I assume it would also work for regular DVD vs. HD-DVD/BluRay

Here you go, Jack. Settles everything, right?

Thanks !

I think the article is telling me that there are two different factors affecting seating distance -- one being the optimum viewing angle for best visual impact, and the other being getting as much detail as possible.

The clear message is that at any HT resolution available today, sitting at the optimum viewing distance for best visual impact (eg. the 36 degree THX recommendation) means that we could benefit from quite a bit more resolution -- or, alternatively, that we could sit much further back than we normally do without losing our ability to see all the detail in a current HT picture.

Going with the 36 degree THX recommendation means that (a) sitting at 11-12 feet is about right for my 7-8 foot wide image, and (b) we can upgrade a few more times before our eyes become the hard limit for how much more detail we can see.

I can live with that.

Thanks John. I've got that article bookmarked. I'm still confused.

Here's the article Nick referred to.

AHA! From that article:

"Let’s say you have a 50-inch TV that has a resolution of 1280 by 768 and the vertical height of the display is 24.5 inches. To get the viewing distance, divide the height (24.5-inches) by 768, and then multiply by 3,400. For this example we get a viewing distance of 108.8 inches. So, for that 50-inch, 768p resolution TV, we should sit about 9 feet away. Sit farther than that, though, and we won’t resolve the detail. Sit 9 feet away from the 1080p display and it won’t look any better than the 768p display."

Nick, I hope you won't take the following as criticism for that is not how it is meant. I'm grateful for you bringing this whole thing up. I'm learning stuff here.

I see where Nick was confused, or at least confused me. The example above shows that if you're sitting the optimal distance from 768p set (e.g. 9'), then at that distance, a 1080p set won't look any better. BUT, if you move to the optimal distance for a 1080p set (77.13" = 6.43'), a 768p set should look worse than the 1080p set.

The point is, if you're locked into sitting a specific distance from your HDTV, there is no need to spend the money for an HDTV with a resolution greater than what is optimal for that distance.

I have owned two HDTVs, a 43"/720p set, and now a 56"/1080p set. According to the formula above, the optimal distances for these sets is 43"/720 TV is 8.3', and 7.2' for the 56"/1080p TV. Interestingly, I have been sitting between 7 and 8 feet from both. Pure dumb luck I assure you.

Equally interesting is that if you compare the formula in the article Nick provided to the formula in the article I provided, for a 56"/1080p set, one recommends a viewing distance of 7.2', and the other 11.43'. I'm so glad there is agreement on this issue.