Binoculars Field of View Explained
Are you wondering about the linear field of view and the angular field of view for binoculars? Hopefully the following explanation will answer your questions.
Linear Field of View
Your binoculars' field of view is the length of the area that can be seen from left to right. For example, binoculars rated at 339FT@1000YDS means your field of view will be 339 feet long for objects located a 1000 yards away from your eyes. For birding, it is best to select binoculars that provide a field of view between 315 and 390 feet.
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Angular Field of View
A binoculars' angle of view is measured in degrees. A linear field of view of 339FT divided by 52.5 translates into 6.45 degrees, so the view through the lens will expand away from your eyes at 6.45 degrees.
Calculate Angle: 339FT / 52.5 = 6.45 degrees
Power
For watching birds in flight, a wider field of view is preferable, so you can track them across the sky. However, that means less power which means less clarity. Smaller angles of view will give you better quality images and are good for perched and nesting birds.
Often times, the linear field of view will be stamped on the binoculars. From there, you can calculate the angular field of view. If you don't find this information directly on the equipment, look for them in the manufacturer's specifications.
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Next: Read the "Binoculars Basics for Beginners" article...