May 31, 2011
To get the most from your hunting glass, make sure it's adjusted for your eyes!
by Wayne van Zwoll
All binoculars worth using must be focused. If you encounter a binocular with "permanent" or "automatic" focus, shun it as you would a bouquet of poison oak. Such a glass is not only of inferior quality; it will strain your eyes.
"I-F" or individual-focus binoculars have a focusing dial on each barrel. When adjusting for a new distance, you must re-focus each separately. Here's how: With both eyes fixed on the distant object, cup your left palm over that objective lens, and focus the right-hand barrel for your right eye. Reverse, and repeat the process for your left eye. Be sure you're looking at the same object!
"C-F" or center-focus binoculars are more popular. They feature a center focusing wheel, plus a dial on one (typically the right-hand) barrel. The dial may also be mounted on the hinge with the center wheel. To focus, hold your right palm over the right-hand objective lens, then turn the center wheel until your chosen target appears tack-sharp to your left eye (remember: keep both eyes open!). Now cover the left-hand lens and use the dial to focus the right-hand barrel for your right eye. When you want to glass at a different distance, you need only turn the wheel, as it moves both optical systems in tandem. You've already compensated for disparities in vision, right and left. C-F binoculars are not optically superior to I-F glasses; but they are faster to use.
Tip: Keep your binocular focused as close as you might see game. There's usually time to focus for a long look, but you'll want instantly sharp images of animals that must be shot quickly.