The reason why the scope has a narrow field of view is that it uses a lens with a longer focal length. Why use a lens with a long focal length? For a scope, the longer the focal length of the lens used, the longer the overall length of the scope. , whether it is from the accuracy requirements of the internal lens installation or the mechanical clamping accuracy requirements of the optical sight as a whole fixed on the weapon, it will become easier to obtain high aiming accuracy. On the other hand, the rifle scope is not designed for looking at the scenery. When aiming, the width of the field of view has little effect, so it does not pursue a large field of view.
When it comes to the field of view, one of the losses brought about by the telescope when pursuing a large field of view is the deformation of the edge. Looking back at Figure b, if you look carefully, you may notice that although the field of view of the telescope is large, the grid in the view has a slight bending deformation, which is fine for the telescope, and it is also allowed for the photographic lens, but it is fatal for the riflescope. Many people may think that this deformation is nothing. There are scales and differentiation scales inside the scope. When shooting, the center of the cross is often not aimed at the target, but according to the speed and distance of the target. Check horizontally and vertically. That is, it is judged according to the scale in the field of view of the scope and the experience of the shooter, and if the scene in the field of view of the scope is slightly deformed, then the position of the scene seen in the scope will be deviated, which will affect use.
The last difference is that there is no difference in use, but it is more conspicuous in appearance. There are two protruding things on the tube of the optical sight (picture c), that is the adjustment mechanism of the sight.

 

In fact, the telescope also has this thing: ), the location is probably inside the circle marked in the picture above. However, when the telescope leaves the factory, this part has been adjusted by the instrument, and then the outside is covered.
Then why does this part of the scope stay outside?
First of all, why do telescopes have this kind of adjustment mechanism? Not all telescopes have this kind of mechanism. Generally, only binoculars have it. Simply put, it is to make the two barrels of the telescope aim at the same direction. In other words, when one lens barrel of the telescope is aimed at a target, its other lens barrel is also facing the target. This is the principle of optical sights and sniper rifles.

The process of installing the scope will inevitably bring errors, so the real use of the scope is not like in the movie. When it is time to use it, install the scope and aim directly. After actually installing it, you need to test fire first. According to the results of the test, adjust the two knobs on the scope to correct the error between the scope and the impact point little by little.