Agreeing 100% with Cosmowe but HD is not going to solve your brightness issue when venues have ambient light. From your first post, it sounds like you're using a small table top beamer, right? You'll probably need a brighter one (or double up but small beamers are harder to stack) and if you want the image to be crisp, get one with higher native resolution (1600x1200 or 1920x1080 on up).
Ideally, you'll want as many Foot-Lambers that you can afford (and then some....) but if you have ambient light, I'd recommend you have at least 30fL. Here is the spreadsheet I made to calculate fL based on various parameters (in yellow): https://docs.google.com/spreadsheets/d/ ... sp=sharing. Feel free to share it and please send me feedback (I enabled comments in the sheet) if you find it useful or if something is not clear.