It all comes down to what kind of targets you are going to shoot and at what distance. In fact, there are few more things to take into consideration before choosing the scope for your rifle. Many people often believe in the myth that the scope costs more than half the price of the rifle itself, which is not true for modern scopes. In the past, creating a proper, calibrated scope took a lot of skill and craftsmanship, but modern machining tools have made lives easier. The highly accurate milling and machining tools can produce large quantities with consistent quality thus, bringing down the price.
First thing to consider is the distance. The distance from which you will be shooting narrows down your scope selected by a few notches. Long range shooting requires high power scopes with 8x or higher magnification. But, as you increase the magnification, the field of view decreases and so does the light captured by the objective. To overcome that problem there are scopes with larger objectives. Simple, isn’t it? Indeed, it is simple but the chunk it takes out of your wallet won’t feel so simple. Larger the objective, higher the cost.
A 4 x 32mm scope will do well for a nice short range shot. Increase the magnification to 8x or even 12x, and you will be looking at dark images. 12 x 40, or a 12 x 50 scope will do significantly better at light gathering.
Another important factor to consider is field of view. Higher magnification combined with a smaller objective will give you a very narrow field of view. You may find yourself looking at tiny insects crawling somewhere far off in the distance, but you’ll never know exactly where they are because the terrain all looks the same.
So obviously you need a balance between magnification and the scope objective to obtain optimal field of view and in turn aim better.
Let ‘s say you found a cheap scope that has a nice big objective and offers high magnification. Later, you find out the optics are not that great. Bad optics can cause chromatic aberration, blurriness and internal reflections to appear at the eye piece. This can be quite a problem while on the shooting range. Usually, the best quality optics will have coatings on the lenses that prevent reflections and aberration. The glass used on these optics will be super clear and well ground. You may want absolutely flawless, but know that isn’t going to come cheap.
In addition to field of view, eye relief is also another point to take into consideration. Eye relief is the distance you can maintain between the eye piece and your eye. If the eye relief is too close, you may end up injuring your eye while you shoot. Also, shorter eye reliefs will have black ring appearing all over the field of view.
In order to choose the best scope it is important to know certain terms, technological advancements and rifle scope manufacturers which you can easily familiarize yourself with from sites like RifleScopeGuide (below).
Other resources:
https://en.wikipedia.org/wiki/Eye_relief
http://www.riflescopeguide.com/
