Which Rifle Scope Objective Lens Diameter Should You Use? (Choosing Right To Focus Right)

Due to being available in many different sizes, rifle scope objective lens makes us confused when choosing the best ones. But this factor has a substantial impact on the quality of your shots. 

Among the masses, which rifle scope objective lens diameter should you use? In this article, we will give you the answer.


Which Rifle Scope Objective Lens Diameter Should You Use? 

Before getting details about the objective lens diameter, let’s take a quick look at the anatomy of a rifle scope.

As you can see from the image, the objective bell is the largest part of the scope body. This furthest part away from your eyes is also where to house the objective lens.  

Numbers Defining The Scope

When searching for a rifle scope, you will see series like 4-12x50mm. So, what does it mean?

The first two numbers, 4-12, define both the magnification and the lens’s power. In other words, this riflescope has a magnification between 4x and 12x, which gives it a 3x zoom power (12/4). And 50mm means the objective lens diameter of 50mm. 

Assuming that the series shows 6x42mm, for example. In this case, the scope gets a fixed magnification of 6 along with the lens of 42mm.

Objective Lens Diameter Recommendation

We divide objective lens sizes into three categories. They are small, medium, and large objective lenses with different pros and cons.

Small Rifle Scope Objective Lens (28mm and under)

  • Pros: It is a compact, lightweight (10-13 ounce), and budget-friendly type of lens providing a low-profile mount. Besides, the smaller the lens is, the less the chance of light reflection can occur. 
  • Cons: The lens is not efficient for high-powered scopes and the close hunting range. 

Medium Rifle Scope Objective Lens (30-44mm)

  • Pros: The lens often weighs 12-15 ounces only with the compact form and provides a low-profile mount. People tend to use this type for low-light hunting conditions. 
  • Cons: The effective range can shorten faster. 

Large Rifle Scope Objective Lens (50mm and upper)

  • Pros: The large size is perfectly efficient for long and even extreme long-range shots. Not only that, it is also helpful to use in the low light hunting condition when giving the high magnification and improving the image quality.  
  • Cons: It is heavyweight and quite expensive.  

What Are Other Decisive Points When Choosing Objective Lens? 

Next, it is time to discuss several other decisive factors as the following:

  • Weight
  • Glass Quality
  • Power & Portability
  • Magnification Settings
  • Light condition


The first point is about the weight. As we mentioned above, the small or medium lens is often lightweight while the large ones are not. Carrying a bulkier objective lens seems to be a big issue for many shooters. Hence, it is a need to determine the demand to decide how heavy the lens you choose should be?

Glass Quality

The level of clarity and brightness depends considerably on the glass quality of the lens. Honestly, a scope can become useless with poor-quality glass.

For great performance, the lens should come with polarization as well as anti-reflection coatings. In case that your objective lens is not available with the built-in polarization, you can apply the additional polarized filters. Nowadays, many brands provide these types of filters for rifle scopes.  

Power & Portability

The larger objective lens plays a key role in maintaining consistent power at any adjustment. As a consequence, the shooters can get a high scope power even in low light conditions. For this aim, we recommend a lens of at least 40mm. However, the large lens always comes with the heavyweight, which may be a problem if you are shooting outdoors for hours. 

Magnification Settings

The hunting range often gets shorter when the sun goes down. At that time, you must adjust the magnification down to get a usable level of light. If you want high magnification, the larger lens will be better since they can deliver clearer pictures. 

Light Condition

The final factor to take into consideration is the light condition. For instance, shooting at dusk or dawn requires a larger objective lens for more light going through the scope. Conversely, if you plan to shoot under the sun, a smaller lens should be your priority. 


The answer to the question, “Which rifle scope objective lens diameter should you use?” can be different based on your requirement for shots. In this article, we provided some essential information that can help your consideration. 

For further explanation needed, feel free to let us know.

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