There are all sorts of home theater calculators out there that will tell me all sorts of things about distance and screen size and viewing angles, but none seem to be getting me the particular information I'm looking for. Let me see if I can explain:

We currently own an aging RPLCD TV. Because it's so deep, it sits on a stand. This arrangement isn't great for having a baby/toddler around, so we'd like to replace this one with a flat screen, thus entering 2009.

What I want to find out is how large a screen I'll need, when mounted on the wall, to match the area of my vision that the current TV fills. The old TV is on a stand and sits roughly 3' away from the wall. The new TV would presumably be no more than about 3-6" from the wall, meaning a difference in distance of around 2.5' or more.

Now, if I got the same screen size and placed it 2.5' further back, I'd assume that the new TV is going to look smaller. I don't know if it'll look a lot smaller or not, but I'd think it would. What I don't know how to do - because my geometry skills have around 18 years of rust on them - is how to figure out how much smaller the new set would look.

Lets figure the following numbers: Old TV is a 60" screen, viewing distance from directly in front is approximately 13'. How do I figure out what size TV will match the area the old set takes up in my field of vision?

ps-I recognize that I could be perfectly happy with a 60" flat screen, but I like big TVs and I'm looking for some data to use as justification with the wife

Ok. So my envelope drawing I'll try to explain:

13' away and 60" (diagonal vs height shouldn't matter nor should units since it's all ratios) gives a ratio of 60/13 = 4.61

For 15.5'
x/15.5 = 4.61
x=71.5"

So a diagonal of 71.5" at 15.5 feet should be equivalent to 60" at 13 feet.

I think it's that simple. 71.5" seems like about the right number too.

Thanks! I figured it would be a pretty big difference... Unfortunately for me, 70" is usually a huge price jump from 60 or even 65". Must be how the yield from the panels works out...

You could always move the couch a little closer. That's free.

Just buy the screen you want and can afford, and reverse-massage up some numbers to justify it to the bride.

Humans are not rational, we are rationalizing...

While this is not exactly about TVs, you are married and maybe this can help...

Read the post by Matt Leo.

https://groups.google.com/d/msg/sci.astro.amateur/2RYP7WKWwCY/GuT_kgY-IoQJ

Haha, quite true. It's an option, although there's some wires and speaker connections behind it that I'd rather not have the little tyke messing with.


I think we can find a place of compromise I'm just looking at Vizio so we're not talking about TVs that will break the bank. I'm not a videophile so they'll be fine for me, and certainly better than what I have now.


Haha! Amazing. That guy's pretty funny