For Common Center Focus Binoculars
To focus your binoculars, begin by moving the eyepieces closer together or further apart until they are comfortable in front of your eyes and you are seeing one large round field of view.
Make sure that the right eye diopter focus* is set to ZERO. Close your right eye (or obstruct your right eye’s view by putting the right objective lens cover over the objective lens) and look at a distant object using your left eye. Focus the distant image by turning the center focus ring.
Next, close your left eye (or obstruct your left eye’s view by putting the left objective lens cover over the objective lens) and look at the same object using your right eye. Focus by turning the right eyepiece diopter ring.
Once both sides are focused for your eyes, use the center focus ring to focus on objects at different distances and never turn the right eye focus again. Make a note of your diopter setting and quickly focus any binocular by turning the right eye diopter focus to your setting.
*right eye diopter focus may be located in a different location. Most binoculars have the focus located at the right eye ocular lens, some have it located as an extension of the center focus wheel.