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Diopter Adjustment

Michael PorterDiane PorterLocking diopter adjustments

A binocular's diopter adjustment lets you alter the focus of one eyepiece in order to compensate for any difference between your left and right eyes. With the diopter adjustment properly set, both eyes will comfortably focus at the same distance.

The classical diopter adjustment, still used by most Porro prism and some roof prism binoculars, allows you to turn one eyepiece to adjust its focus. On many binoculars, however, the slightest bump undoes the adjustment.

Now, however, top roof prism binoculars lock the diopter setting so that it doesn't accidentally get changed. A ring must be pulled or a knob pushed before the diopter adjustment will move. This is a small but valuable improvement.

Some binoculars that employ such an advance diopter adjustment locking mechanism include the following:

Leica Ultravid
Nikon Premier LX
Pentax DCF SP
Swarovski EL
Zeiss Victory FL T*

 

 


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