CF (Center-Focus) Models
All center-focus binoculars have an independent focus provision in the right-side eyepiece. This is called the “right diopter adjustment” and it’s purpose is to compensate for any difference between your eyes. The adjustment is usually a rotating ring just below the right-side eyecup, or if there is no ring, then the entire eyepiece is rotated to change the setting. This only needs to be set once, and shouldn’t be needed again- unless someone else uses your binocular and changes the setting.
To set the right diopter, look at a distant object. Gently close your right eye and use the center focus wheel to achieve sharp focus on that distant object using just your left eye. Now gently close your left eye, but use only the right diopter adjustment (NOT the center focus wheel) to achieve sharp focus for the right eye. The binocular is now set for your eyes, and only the center focus wheel is used for any change in focus.
IF (Individual-Focus) Models (All Ultra Series, 20×65 ED Deluxe, 25×100 IF Deluxe)
Individual focus can be a little slower to focus than center-focus models, but because each eyepiece is directly attached to its own focuser, they’re highly accurate, and very accommodating for people with vision problems. Operation is simple- gently close one eye, rotate the focuser for the open eye to obtain sharpest focus, then repeat for the other eye.
