Originally Posted by cerberu202
Thanks for the response. I see Carl's FlexiGrey is approx 0.8 gain and as you mentioned will dim the image a bit. Are there any alternatives to ALR that I can buy if not from Carl's. Does painting get me the 1.1 gain of ALR screen or similar experience? Not averse to painting if I cannot get a good ready screen material if the difference would be significant. I like flexigrey but want to find out other options and their price and viewing experience if they have they significant significant differences.
The problems won't come specifically from gain nor screen-color, but the combination of both..the darker your screen-color is compared to its gain (technically a difference over ~2X) the worse it'll be for a ShortThrow.
I believe (but could be wrong) there are a couple couple more grey screens which would also work: Elite's CineGrey Classic (not the 3D nor 5D) is sold on screens or by itself as a ~$65 135inch rectangle of material, SilverTicket's Grey screen (not their Silver) may also be light-colored and low-gain enough to work.
I do think Carl's FlexiGrey will be a little lighter-colored and lower-gain..if so, it'll be the safest choice with the best image uniformity of the pemade grey screens (the Stewart GreyMatte70 would be even better, but much more expensive).
Paint would be able to work very well. Any plain flat/matte light-grey can work well for short-throw because there won't be practically any difference between its color and gain. Similarly, any metallic mix that only boosts the gain by 2X or less compared to the plain color will also work. As an added bonus, keeping the gain boost around or under 2X that of the color also means the paint will be quite forgiving and easy to use.
Your main problem will probably be that 154" is pretty big and the Optoma short-throw is not very bright. The BenQ 2150st short-throw is brighter and also users a slightly longer throw (it'll still be in front of you rather than behind, but less far in front of you), but that BenQ is usually around $800-$900. The regular-throw BenQ would be a couple hundred cheaper, but you'd only get as large as ~131" unless you can place it farther than 11ft back from the screen.
With the Optoma and its 700lumens of peak color-brightness you'll want to keep gain in the 0.7-1.0 range and the color around N7.5-N10 (light-grey on up to white). The paint color "Snowfield" or the slightly darker "Universal Grey" are probably your best paint-color choices with that projector at that size..the slightly darker "Pebble Grey" might be pushing your luck unless you're okay with an overall darker image.