Ok you bought your scope and your scope has an adjustable objective. Or you can’t decide if you want to pay the extra money for a scope with an adjustable objective. What is it and how does it help you? Scope manufacturers build a scope with a specific distance or range in mind. That is where scope parallax comes into play. What is it and how will it affect you and your shooting? Lets answer these questions. First let me try to explain what parallax is and how you will see it.

You have a rifle scope 3x9x50 mounted on your deer rifle. The scope does not have an adjustable objective lens. Sight your rifle in at 100 yards. Now move back to 200 yards and look through your scope and sight on your target. With your gun in a solid rest move your eye from side to side in the eye piece watching your crosshair move side to side on the target with your eye movement. That is scope parallax. In a non adjustable scope the factory sets the parallax at a specific distance. If the target is closer than the factory set distance the image falls behind the reticle plane and there is parallax in the system. On the other hand if the target is further than the set distance of the scope, the image falls in front of the reticle plane and we again have parallax present.

So when you buy a scope with a fixed objective lens, You can sight it in at 100 yards and at 200 yards you could be off target 6 to 12 inches. Just because you do not hold your head in the exact place behind the scope every shot. No doubt you will blame this on your rifle or your ammunition. A scope with an adjustable objective allows you to adjust the scope to the range you are shooting to eliminate parallax.

If you are obsessed with long range accuracy as I am you will spend the extra money for the scope with the adjustable objective.

Also, If you want to scope a .22 rifle for example. Manufacturers make rifle scopes specifically for rimfire rifles, That means they build the scope with a maximum range of 50 yards in mind. Think parallax, so if you scope a rimfire rifle you will want to buy a scope made specifically for rimfire balistic’s or buy a scope with an adjustable objective that allows for short range adjustments.

Don Davis
Gunsmith
Snake River Hunting Club