Bright is not always better.. Many of the modern clear screens actually make it harder to accurately focus.
That is because some of the light from the lens passes straight through the screen and your eyes focus through the lens instead on the screen.
For an example just look at a screen with a 'clear spot' to see the effect. Or look st the split image portion of a screen an notice that the two images dont really go out of focus.
Coarser screens will 'snap into focus' better but loose some light in the process.