Binoculars.org

Huh?  Really?  You need to learn something to focus a binocular??  Don’t you just turn the knob until the image is clear?  Nope.  There is a little more to it.

You would be surprised how many binocular owners do not know how to properly focus their binoculars.  There are two differnent focusing systems used in binoculars – Center Focus Binoculars and Individual Focus Binoculars

Focusing Center Focus Binoculars

The most common binocular is the Center Focus style.  This is the binocular that has a simple focus wheel inbetween the eyepieces.  Turning the wheel changes the focus.  But there is one important step most people forget when focusing a binocular – the diopter adjustment.  You will see that the eyepiece on the right side of the binocular can twist – this is called your diopter adjustment.  Because most peoples right and left eyes have some variation between them, its important to get that difference properly adjusted.  Its really easy to do:

Start by pointing your binoculars at a distant object.  Look through the binoculars and close your right eye.  While looking through only your left eye, focus the binoculars focus wheel so your left eye is in focus.  Next, close your left eye  view through the binocular with only your right eye.  Now without turning the focus wheel - turn the diopter adjustment on the right eyepiece until your right eye is in focus.  Now you have properly set your binoculars for your eyes.  Now you can simply focus the binoculars with the focus wheel and leave the diopter setting alone.

Focusing Individual Focus Binoculars

A binocular with Individual Focus will not have any focus wheel.  Each eyepiece is individually turned and focused for each eye.  Simply look through the binocular at a distant object and focus each eye while the other is closed.  You will not need to re-focus the binocular until you look at something at a different distance.  This is why most binoculars are of the Center Focus design, because you may be changing distances frequently and the focus wheel is much easier to keep precise focus.  However, you will find binoculars with individual focus quite useful for certain applications.  For example, it is very comon to find marine binoculars with Individual Focus.  When you are out at see and have focused the binocular at a couple hundred yards, you will rarely need to ever re-focus.  Everytime you pick them up, they will be perfectly in focus and ready for use.  This is also true for many astronomy binoculars.  You can simply focus them at distances in space and you will only make slight adjustments to focus.