Diopter locking mechanisms
by Diane and Michael Porter
Some binoculars (especially high quality, expensive ones) have locking mechanisms to prevent the diopter setting from getting turned accidentally. The locking mechanisms are varied and often ingenious.
On the Minox HG binocular, you unlock the diopter adjustment mechanism by lifting the silver ring on the right eyepiece (revealing the scale) and turning the ring. When you have it right, you push the ring down again, and the diopter setting is locked until such time as you need it again.
The Leica Ultravid roof prism binocular has an especially elegant diopter solution. There are two knobs on the central column.
Normally, when you are using the binocular, both knobs turn as one, so it's like one big, easy-to-find knob. It looks like the picture above left.
To change the diopter adjustment, you lift the upper knob. The right-hand picture above shows the knob in the up position, revealing a stripe of red. In this position, the upper knob turns independently of the lower focusing knob, fine-tuning the focus of the right eye only. As the knob turns, you can see the adjustment on the face of the scale.
If you are not clear about where the diopter setting is on your binocular, consult the manual that came with it.
Armed with this understanding of the diopter adjustment, you can allow your binocular to do its best for you.
Copyright 2006 Michael and Diane Porter