Front lens - Binoculars
The size of the front lens determines how much light enters the binoculars. What consequently happens to all this light of course depends largely on the other features of the binoculars.
In high-quality binoculars, the front lens has a (multi)coating. The other lenses in the binoculars also have this coating. However, in the front lens, it is also important that the mechanical quality of the coating is in order. The coating must obviously be tough enough to withstand any bumps and jolts to avoid any damage to the lenses. However, it goes without saying that binoculars must be handled with great care at all times.