When you are looking for binoculars and have figured out the basics, here are some extra features you might want to keep in mind. BaK4 prisms are expensive but your binoculars will give you a tight, sharp image and without tiring your eyes. When your eyes get tired you tend to headaches, and the binoculars will not be your friend.
Another catch phrase is “phase corrected.” Light coming into the lens is split by the aforementioned prism, leaving you with light streams that may get out of phase. A better pair of binoculars coats the lens to avoid this out of phase tendency.
Diopter Correction lets you key the binoculars to your own eye prescription. Make sure the binoculars have click stops to maintain your correction. Anytime your birding buddy borrows your binoculars he adjusts them to his eyesight. With click stops it is a breeze to get them back to your particular eyesight and keep them there.
A lifetime warranty would be a great help too. Just some details in a higher level binocular you won’t want to live without