OK - Regarding viewing angles. The SMPTE and THX specs are only for vertical dimensions (i.e. 30 and 36, respectively). The 15 degree horizontal I used for estimating screen height was derived from typical human optimal cone of vision.
I think you might understand now, but if not, its horizontal we've been talking about. Refer to link above for vert.
Discussing horizontals first:
When comparing a calculation for horizontal viewing angles for a 2.40:1 vs a 16:9 screen, I'll assume that the only difference would be the distance from the screen. To get a 36 degree viewing angle on a 16:9 screen, you'd have to be closer than for a 2.40:1. Yes?
No. Well, not necessarily. It all depends on screen width for this measurement, HOWEVER, with a wider aspect such as 2.4, you can often sit closer. For many crazy videophiles, they use a 1 to 1 screen width : seating distance ratio. This is too close, IMO, for 16:9 viewing. And that comes from someone who likes it really big.
So, you will have to consider the quality of your source material, as well as the ARs you mostly watch. I watch mostly wider aspects and exclusively watch native hidef. That's why I can put the front row at 42 deg, for my tastes.
I used the tool at
http://myhometheater.homestead.com/viewingdistancecalculator.html, to derive my distance from the screen, and the only screen options provided were 4:3 and 16:9. Using the 16:9 option and my 92" screen size (leaving distance blank), the tool recommends around 10.5' for THX spec and 12.5' for SMPTE spec.
With MY preferred viewing angle, I would be at slightly closer than 9 ft. If I actually had a 2.40:1 screen, you can bet the farm I would be even closer, if only a little.
If I move my (primary seating) couch back far enough to meet the THX spec, the rear couch HAS to go on the back wall. My room is only 16+ feet deep. If I want two rows of seating, AND to get close to the THX/SMPTE specs for distance, I'd need a room in the neighborhood of 20-25 feet deep to put the entire seating area in the audio "sweet spot". Unfortunately, I didn't build my media room that big.
Going by what I said above, you would probably have a couple feet away from back wall. Every bit will help you . . . but, yeah, its a tough balancing act.
If the tool above is right (or close) I will have to sacrifice rear row audio quality in order to optimize primary row viewing distance.
Quite plausible.
We hope so.
Thanks for all the help everyone. I always tend to over analyze these kinds of things, but in general it helps with the quality of the final product...
Chris
OK. Can no one hear me? Is there ANYTHING WRONG with firing the pic at a blank wall? Its much, much, much easier and its much, much, much more accurate in acheiving total satisfaction.
No one I know using this method has any regret. There are waaaaay too many folks who do have regrets when they attempt to over-analytically predict. I assume you read the little anecdote I shared in my last post.
I have a hard time coming up with an analogy, but I'll feebly attempt one. To me, over-analytically predicting screen size, rather than throwing up the pic itself to see, is akin to taking mulitple measurements of your chest, waist, arms, neck, etc, to see if a shirt fits just right and looks good, and then ordering the $300-1000 piece on-line. Its easier just to try the shirt on, less hassle, be absolutely sure, and THEN order it online.
Then add personal preference into the equation, (some like it loose, some it tight, some might want to show off their guns, some might want to hide their gut, blah blah blah blah)
