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Parts Of A Rifle Scope: Different Part Terminology 

Andrew Maurer | Updated February 25, 2024 | Why You Should Trust Us | How We Earn Money
Cover photo of parts of a rifle scope with a scope mounted on a rifle

If you haven’t gotten to know the essential components of a rifle scope, you’ll probably never use it to its full potential. But good thing that you’re here for a comprehensive breakdown.

Find out the key parts of a rifle scope and the need-to-know terminology to make the most out of your scope and achieve the best accuracy.

For similar reading see our post on the best scopes for 6.5 Creedmoor rifles.

Key Takeaways

  • A rifle scope has a combination of external and internal components that work together to improve a shooter’s accuracy.
  • Objective lens, eyepiece, and adjustment turrets are some of the external features that interact with the internal lens assemblies and erector tube assembly within the scope.
  • Understanding rifle scope terminology and numbers, such as 3-9×40, is essential to maximize the performance of the scope and ensure you’re using the right scope for your situation.

What Are the Main Parts of a Rifle Scope?

Close-up of the objective lens of a scope

Objective Lens

The objective lens is the front-facing glass element that gathers light in a rifle scope. This lens has a larger diameter than the ocular lens and transmits light to the erector lens, which then flips and magnifies the image.

Ocular Lens

The ocular lens is the glass piece facing the shooter when aiming. It focuses the light collected by the objective lens into the eye of the viewer, offering a clear and bright image.

Objective Bell

The objective bell is the tapered front part of the scope that houses the objective lens. Its main function is to protect the objective lens from damage and external elements.

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The eyepiece is the part of the scope at the rear end, holding the ocular lens. It often offers adjustable diopter settings, allowing the shooter to fine-tune the focus for their individual eye preferences.


The scope tube connects the objective and ocular lenses of a rifle scope. It is typically made of durable materials like aluminum and is designed to hold the internal components of the scope securely.

Overhead view of a rifle scope and earmuffs and wooden planks

Magnification Power Ring

The magnification power ring is found on variable power scopes, allowing the shooter to adjust the magnification level for different shooting distances. It controls the position of the magnification lens inside the scope.

Elevation Turret

The elevation turret is an adjustable knob found on the top of the scope. Each click corresponds to a specific increment in elevation, allowing the shooter to fine-tune the point of impact on the vertical spectrum.

The number of clicks per adjustment varies depending on the scope. For example, a common adjustment is 1/4 MOA per click, which will move the point of impact about 0.25 inches at 100 yards.

View of three turrets on a rifle scope

Windage Turret

The windage turret, similar to the elevation turret, is an adjustable knob, but it is positioned on the side. Windage adjustments help shooters correct for horizontal deviations caused by wind and other external factors.

Parallax Error Adjustment

Burris scope ring and rifle scope parallax knob

Parallax error adjustment is a mechanism found on some scopes, allowing the shooter to adjust the focus so that the reticle and target are on the same focal plane. It helps to eliminate optical illusions and minimize parallax-induced errors in shooting.


Scope view of hills and shrubbery and dead hold BDC reticle

The reticle, often referred to as “crosshairs,” is an aiming reference point within the rifle scope. It’s available in different styles and is typically placed on either the first or second focal plane. The reticle helps the shooter to take precise shots at various distances.

Other Rifle Scope Terminology

Eye Relief

Eye relief refers to the distance between a shooter’s eye and the ocular lens of a riflescope while maintaining a full field of view. It is crucial for comfortable shooting, especially with high-recoil rifles, to prevent injury to the eye

Different scopes offer varying eye relief, with some providing longer eye relief to enhance safety and comfort when shooting.

Rifle scope mounted on a hunting rifle held by a hand

Eye Box

The eye box is essentially the area behind the ocular lens where a shooter can position their eye and still see through the scope clearly without any shading of the edges.

A generous eye box allows for flexibility in eye position, making it easier to acquire targets quickly and accurately. The size of the eye box depends on the scope’s design, including factors like magnification and field of view.

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Exit Pupil

Now, the exit pupil is the small circle of light that appears when looking through a riflescope. It’s the result of light passing through the objective lens and being focused on the shooter’s eye. 

The exit pupil’s size determines the amount of light entering the eye, affecting brightness and clarity in low-light conditions. A larger exit pupil typically provides better light transmission, offering a brighter image for the shooter.

What Do the Numbers on an Optic Mean? 

The different optic numbers on a rifle scope represent the magnification power and objective lens diameter

Vortex scope 4-12x40 eyepiece

For instance, in a scope labeled 4-12x40mm, the ‘4-12’ represents the magnification range, meaning the image can be magnified from 4 times up to 12 times closer than it appears to the naked eye. 

The ‘x’ denotes ‘by,’ connecting the magnification and lens diameter. The ’40mm’ indicates the objective lens diameter, which affects the amount of light that can enter the scope. The larger the diameter, the more light that can be captured, resulting in a brighter and clearer image. 

Remember, higher magnification reduces the field of view, while larger lens diameters typically result in a larger and heavier scope. Understanding these numbers is crucial for choosing the right scope for your shooting or hunting needs.

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For more see our guide on how to mount s scope on a rifle without a rail.


What are the dials on a rifle scope called?

The dials on a rifle scope are referred to as turrets. They’re generally found on the top and side of the scope, allowing for adjustments to be made for windage (horizontal) and elevation (vertical). 

What do the different parts of the scope do?

The rifle scope has many different components, each serving unique functions: the objective lens allows light transmission, the erector lens inverts images, the magnifying lens enlarges images, and the ocular lens offers clear views of magnified images.

What are the parts of a rifle scope?

The parts of a scope can be separated into three different sections: the eyepiece, the tube, and the objective bell. Each part serves a unique function in the image viewing and magnification process.

What are the names of the parts of a scope?

The names of the main components of a rifle scope include external parts such as the objective lens, objective bell, scope tubes, adjustment turrets, power ring, eyepiece, and ocular lens. Internally, a rifle scope consists of the objective lens assembly, focus lens assembly, and erector tube assembly.

What are the 3 dials on a rifle scope?

The 3 dials on a rifle scope are the elevation adjustment (for up and down movement), windage adjustment (for left and right movement), and the parallax adjustment or focus knob (to adjust the focus and remove parallax error).

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