Gun with rifle scope

rifle scope expands your target area, allowing you to aim your gun more precisely during shooting. 

If you are new to the world of rifle scopes and want to understand how they work then keep reading. 

The goal of this article is to give you a functional understanding of how a rifle scope works.

How Does a Rifle Scope Work?

A rifle scope is a metal tube that rests on top of your rifle. It has a collection of glass lenses inside it, and as a visual tool, it allows you to see farther than your natural eye.

Think of your camera, telescope, or binoculars. These are all-optical devices that work almost the same way as a riflescope.

The lens nearest to the target captures light and sends it to the one nearest to your eyes.

Light bounces off objects in various directions. Aiming the scope at the target allows it to collect that light. Another type of lens inside the metal tube then readjusts the image so that it comes into view as per your desired angle.

On reaching the magnifying lens, the image is enlarged and transmitted to your eyepiece.

What differentiates riflescopes from other optical devices are the lenses in between. Lenses are undoubtedly the most integral components of a scope. And therefore, learning the function of each lens is important as you'll understand how your riflescope functions.

Objective Lens

The objective lens is held in position by the objective bell, which measures approximately 40 or 50 mm. It is the largest and bulkiest section of the riflescope.

The objective lens of the scope gathers waves or particles of light from the subject or target under observation. It is the farthest section from your naked eye.

Modern rifle scopes come exclusively with coated objective lenses. Here are the benefits of a coated objective lens:

  • Minimize light reflection
  • Allow gathering of the maximum amount of light
  • Enhance image quality
  • Preserve vivid colors from natural settings
  • Scratch-resistant
  • Water-resistant

Erector System

The erector system houses the following:

  • Erector lens
  • Magnification lens, and
  • Reticle

They all work to enhance your target image. The erector lens corrects the upside-down images produced by the objective lens. It adjusts the image of the subject so that what's transmitted to your ocular lens is an image that's right-side up. If it were not for the erector lens assembly, you would be pulling the trigger on upside-down targets.

At times, conditions may not be suitable, and you may have to assume uncomfortable body angles to put your target in focus.

Luckily, riflescopes come with adjustment controls for fine-tuning your object acquisition. These controls are housed in the erector tube area and include:

  • Elevation
  • Windage
  • Parallax

The reticle's elevation adjustment also occurs at the erector tube. The reticle, also known as a crosshair, is a series of fine lines that center your rifle scope on your target.

These markers influence the size and position of your target. They also allow you to be more accurate when shooting.

That shows the great importance of the scope's erector assembly. Similar to other previously mentioned glasses, coated options are ideal for minimizing light reflection and loss.


The erector lens and magnification lens move back and forth in harmony along a track that's appended into an internal, secondary tube. Both lenses expand and contract. And the distance between the two enlarges the image.

The longer the tube, the greater the space available for the two lenses to move. And the farther the distance between the two lenses, the higher the scope's magnification capabilities.

The erector lens and magnification lens also produce a second focal plane. A focal plane is the riflescope’s section where your target or prey is at its sharpest and parallel to your eyes. In a second focal plane, the reticle is situated behind the erector system. It is nearer your eye. Thus, it's not magnified.

But in the first focal plane (FFP), the reticle is placed in front of the erector assembly. It is nearer to the objective lens. In this case, there's a greater magnification of the reticles.

The reticle in a scope with a first focal plane will contract and expand based on the magnification settings of your variable power scope. But a second focal plane (SFP) reticle maintains the same size irrespective of the magnification settings.

Of course, your desires and shooting needs will determine the focal plane you choose. FFP riflescopes are ideal for long-distance shooting, while SFP rifle scopes are perfect for regular hunting.

Ocular Lens

The section of the riflescope that's closest to your eye is the eyepiece assembly. It is the final destination after light passes through the erector assembly and the reticle plane. It houses the ocular lens, the nearest focal point when looking through the scope.

Inside the eye assembly, the light goes through the ocular lens, which allows you to focus the image and the reticle on your eye. The ultimate focal point is the exit pupil.

The exit pupil refers to the light-based spherical image that the riflescope delivers to your eye.

The light rays from your target pass via the virtual aperture and away from the scope. The diameter of your scope's exit pupil affects what you see and the clarity of the images. A larger exit pupil is perfect for evening shooting, while a small exit pupil is good in the daytime.

For heavier rifles with low-recoil like the AR-15, the exit pupil may be nearer the ocular lens. Therefore, this would allow for quicker target acquisition. Meanwhile, high-caliber bolt action guns may come with a longer exit pupil. This would mean more freedom for you to figure out your ideal eye position and avert potential recoil from your gun.


With a myriad of riflescopes in the market, knowing how a scope works is the first step towards a better buying decision.

If you have any questions about our scopes (or any of our products) please reach out. Our team is happy to answer any of your questions. 


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