Digital Binoculars are often referred to by two numbers separated with an "x", for example, 8x30. The first number is the power or magnification of the binocular. The second number in the formula (8x30 or 8x42 or 10x25) is the diameter of the objective or front lens in mm. The larger the objective lens, the more light that enters your digital binocular, and the brighter the image that you see through the binoculars. Please note that the Objective Lens Size does not affect the brightness of the digital picture since for most digital binoculars cameras (unlike digital spotting scopes and digiscoping setups), the built-in camera has its own lens.