I went to this site:http://www.projectorcentral.com/cons...cfm?ci=formats
and found some common sense about screen sizes.
Since I have a 4:3 CRT projector, I will put up the largest 4:3 screen possible.
Here is a teaser from the article--- go to the site for the full article. It is written by Evan Powell at projectorcentral.com. It is really good reading:
"Consider this for a moment. Most people will install the widest screen they can fit into the space available, regardless of its format. So screen width is almost always the limiting factor. In my theater I can install a 16:9 screen that is 8 feet wide, or a 4:3 screen that is 8 feet wide. If I install a 16:9 screen it will be 8 feet wide and 4.5 feet high. If I install a 4:3 screen, it will be 8 feet wide and 6 feet high.
Now between these two options, how big is my 4:3 image? On the 4:3 screen it is 8 x 6 = 48 square feet. On the 16:9 screen, it is 6 x 4.5 = 27 square feet. Almost half the size! That's the difference between being at the Eagles concert and seeing it on television.
Meanwhileâ€”and here is a key pointâ€”my 16:9 image size is the same either wayâ€” 8 x 4.5 = 36 square feet. So the only variable is how I want to display 4:3. Do you want to maximize the use of your wall space? The 4:3 screen gives you more viewing area since it uses more vertical space on the wall."
I still need help... and 8' by 6' screen... this seems reasonable to me. What do you think?