There are three distinct focus systems currently available. The military or European type requires a separate mechanism for each eyepiece. This is a slow, awkward process, good for tripod-mounted optics and little else. If the subject you're observing moves around a good deal, this type can be troublesome, as you're spending inordinate amounts of time on focusing.
Center focus are more common in this country. This type is far easier to use. Calibrate them once to your eyesight, then use the center knob to focus both tubes.
Here's how to do that:
- Start by shutting your right eye and leaving your left eye open
- Use the center knob to focus on an object about 20 yards away
- Open your right eye
- Next, shut your left eye and leave your right eye open
- Using the focus ring on the right ocular lens (the one nearest your eye) focus on the same object until you can see clearly
- Look through the binoculars with both eyes open, and you should have a clear, crisp view of the object
It's that simple!
In the movies, people are always passing binoculars back and forth. In fact, because focus is calibrated to a user, the images will be out of focus for the second user (unless, of course, the two people had identical vision).
A step faster than center wheel focusing is the fast-focus bar available on some models. This is a hinged, flat plate, rather than the wheel. It is slightly faster, and certainly less awkward, to focus, particularly if you're wearing gloves. By pressing either the right or left side of the bar, you focus the binoculars.
Even faster are the permanent focus binoculars that have been around for a decade or so. There is still some confusion about how they actually work. Contrary to popular belief, they are not "self-focusing" or "auto-focusing." Instead, sophisticated optics use your eye's natural focusing ability to do the job. The bottom line: everything from about 40 feet to infinity remains in focus with no additional adjustments required.
As wonderful as the permanent focus binoculars are, they do have a couple of drawbacks. To use them, you must have perfect vision, or vision that has been corrected, or you'll have problems seeing clearly. And they are not effective at a range of less than 40 feet.
Learn even more about Binoculars. Continue on or click any of the links below to go directly to that topic.
