“Auto-focus” binoculars are binoculars of which the focus has been set at the factory, so actually there’s no “auto-focusing” happening. With these binoculars images are always in focus from some 10 to 20 yards to infinity. This means that these instruments also have wonderful depth of vision. Since their focus has been pre-set at the factory, they have no adjustable central focusing mechanism, which makes handling very easy.
Two classes of auto-focus binoculars can be distinguished: Auto-focus binoculars with diopters and Auto-focus binoculars without diopter. The first class represent good quality instruments in the middle price range ($150 – $600). Unlike normal binoculars they have diopters for each eye. These have to be adjusted for each eye and once that has been done and the settings fixed, the viewer can enjoy viewing without worrying about focus anymore. This class is perfectly suited for an environment where focusing could be a problem, like from an unstable platform like a boat, or when viewing fast moving objects, in particular when they tend to move towards you, like exhibition airplanes or certain types of birds. Excellent instruments for certain situations.
The other class (without diopters) are not recommended since they make no room for differences between your two eyes. However, they are cheap and could be an option if you really don’t want to spend much on binoculars.
In “Auto-focus binoculars” all the pros and cons of this category of binoculars are discussed, including a review of recommended binoculars with diopters and without diopters.