diopter

Most high-end cameras come with diopters that allow photographers to calibrate the viewfinder to match their eyesight. Adjusting the diopter is easy: simply stare through the camera while turning the little dial or knob found next to your viewfinder (the one with the +/-). Once the scene is sharp (assuming the lens is focused), you're done!

Apparently one of the dangers of diopter adjustment---for some camera owners at least---is accidentally stabbing your eyeball with your finger.

ClearViewer is the compact camera's equivalent of a DSLR viewfinder attachment. It's a folding high-diopter lens that lets you use your compact camera's LCD screen as an electronic viewfinder by putting your eye less than 2 inches away from the screen. This lets you see fine details in the shot, make precise manual focus adjustments, and avoid the problem of glare.