Optoma HD23 Projector Screen Recommendations
The Optoma is a nicely bright projector for movie viewing, in that the projector manages about 1100 lumens in multiple modes with good color, and 713 measured lumens calibrated, with excellent color.
The trick in most non-cave-like rooms, is to match a projector like this with a screen that can keep any reasonable ambient light under control.
Some owners won't be concerned about viewing in the day time. Others will. Some of you are likely to be gamers, the rest sports or movie fans - or just smart people who watch a lot of TV and wisely concluded that a projector is the best way to go.
Ideally, you want this projector placed so that the screen wall is not facing a back wall with lots of light. A screen can help a great deal if the ambient light is coming from the sides, but not if it's coming from straight back.
I want to emphasize that even the slightest ambient light is seen on a white screen, when coming from the side, as you can see in the images above.
High power screens - very high gain white screens effectively do the same thing, and provide a very bright image, but there's a trade-off. You have to be sitting close to dead center to get that brightness. Sit 4-5 feet to the side, (on a typical 100 inch screen), and most of it's gone, and it starts getting dim instead.
Now if you are only planning movie viewing at night, and can turn off any annoying lights, then you are likely better served with a white screen with modest gain - 1.0 to 1.5. 1.3 to 1.5 gain screens get you a noticeable boost in brightness without too much downside. They will even reject a minor amount of side lighting, but they aren't the cure for that problem.
The HD23 isn't 3D capable so that, at least, simplifies. 3D projector owners need to deal with 3D viewing that is a fraction as bright as 2D, creating a challenge for finding the ideal screen.
Keep things simple. If you are mounting the projector, the closer to the screen the brighter the projector (due to optics). Every bit helps, but we're not talking a really signficant difference (an extra 10-20% brightness).