Compact binoculars are developed to provide a small, lighter weight binocular which can be more easily carried. The advantages of compact binoculars is their small size, convenient use and they are great when you want to transport them with you when hiking or when larger binoculars are just not convenient to use.
But compact binoculars generally do not offer the brightness that larger binoculars do. Remember the discussion above about "exit pupil"? Compact binoculars generally do not have large exit pupils which means in low light conditions you will not see a bright or sharp image. For example, a 10x25 compact binocular has an exit pupil of only 2.5mm. During the day this is not a problem. But for early morning or late afternoon viewing they will not provide as much light as a larger standard design binocular.
