Simmons Scopes and Simmons Optics Information

A condition that exists when the image being viewed through a rifle or pistol scope doesn't fall squarely on the reticle. Parallax can be detected by moving your eye left and right, up and down, as you look at the target through the scope. If the image seems to move in relation to the reticle, you have parallax. A fuzzy, out-of-focus image does not indicate parallax, but simply points to improper focusing of the eyepiece for the user's eye. Most big-game hunting scopes are set parallax-free at 100 yards, and parallax present at longer and shorter distances causes such a slight sighting error that it's of no concern to the shooter. However, on target and varmint scopes that are used for shooting very small targets often at long range, parallax can be the difference between a hit and a miss. Varmint and target scopes should be equipped with an adjustable objective lens so that parallax can be removed at various distances. By moving the objective lens axially, the image is focused on the reticle plane and sighting error is eliminated.

Speed Focus: Featured on the 44 Mag series. Fast focusing is done at the rear of the eye bell. Do not force your fast focus ring past its stop point or permanent damage to the scope will occur.

This refers to the distance at which you must place your eye behind the eyepiece of a rifle or pistol scope in order to see the entire field of view. Although the optimum distance is quoted in specifications, there is usually some latitude so that your eye need not be placed at exactly the same place each time in order to see the whole field of view.

Pistol scopes have very long eye relief because they are held at arm's length. Because shooter's arms vary in length, pistol scopes have considerable latitude where eye relief is concerned. Pistol scopes with 4x magnification have a maximum eye relief of 22 or 23 inches. However, pistol scopes of high power have what is called intermediate eye relief, a distance of around 16 to 18 inches.

The diameter of the circular field seen through a scope or binocular is known as the field of view. It's usually expressed in terms of feet at 100 yards for scope sights and in feet at 1000 yards for spotting scopes.