What the best binoculars have

  • A magnification of 8x to 10x. Binoculars with a magnification of 10x or more are heavier than 8x binoculars, and they can be harder to hold steady. For bird-watching, experts recommend an 8x binocular.
  • A wide field of view. Binocular reviews recommend a minimum field of view of 300 feet. Beginning bird-watchers need an especially wide field of view, which makes it easier to track birds in flight.
  • An exit pupil of 2 mm to 4 mm for day use, 5 mm to 6 mm for low light and at least 6.5 mm for night use. This this depends partly on how well your own eyes adapt to dimmer light. The exit pupil is just the ratio of the aperture to the magnification, and it is only a rough guide to the image brightness in various conditions since optical quality can affect brightness more.
  • Fully coated lenses. Multi-coated lenses are better, while fully multi-coated lenses are best, meaning that all lenses are multi-coated on both sides. These coatings improve brightness, contrast and color accuracy.
  • A center focus knob with adjustable diopter. The diopter control adapts the focus to accommodate to natural differences between your eyes, so that one central focusing knob controls the focus once the diopter adjustment is made. Individual focus is too slow and awkward except possibly for astronomy binoculars, while auto-focus and fixed-focus binoculars aren't sharp enough.
  • A tripod socket. Some binoculars lack this feature. Others have a socket but require relatively expensive adapters in order to use it.

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