Depth of Field of Binoculars

This parameter refers to the distance from "near to far" that is in focus at a certain setting of the focus adjustment or at a certain distance. In a given system, as the magnification increases, depth of field decreases. This fact is one of the disadvantages of observing with high magnifications and why depth of field is usually more important in comparing spotting scopes or telescopes than binoculars. At very high magnifications, the depth of field can be so shallow that precise focusing is critical and so the location, size, action and feel of the focusing adjustment is an important consideration. Depth of field also changes with the distance observed, usually decreasing in depth as the distance decreases.

Thanks to our friends at Eagle Optics for providing this information!

See also:
Spotting Scopes—Tips for choosing the right spotting scope
Birding Tripods—Tips for choosing the right tripod for you binoculars and scopes

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