Often times we're influenced by friends when buying a scope. We should educate ourselves first
For the next few days, we're going to talk about "glass". Not the type in windows or in drinking containers, but in the scopes that we use on guns (and crossbows) and how we should go about chosing them.
Cost isn't always an indicator of quality, but in scopes, you can bet - up to a point- it's going to tell you the quality of a scope. This cost is driven by the quality of the glass used, the number of lenses, and the production methods used in the manufacture.
I'd bet few of you ever consider what's inside that metal tube setting atop your favorite rifle but you should. A simple scope has an ocular and an objective end. From the ocular where your eye is, to the objective to where the "object" appears requires that several lenses be strategically placed to insure a clear image is provided to the eye. A "variable" scope allows you to "telescope" that image.
In today's market, the 4x9 is one of the most popular. That simply means that at it's lowest magnification, an object will look 4 times bigger than what's seen by the unaided eye and that by turning the magnification ring, can appear to be 9 times greater.
Good scopes are filled with inert gas (like nitrogen or argon) and then hermetically sealed so that you lens won't fog up during temperature and humidity spikes.
The best rule of thumb for buying a scope is that if you pay less than half than what you paid for the gun, you need a better scope.