What is a Rifle Scope Objective Diameter?

If you are a hunter, the higher are the chances that you are already familiar with the rifle and its perks. Moreover, if you are new to the hunting and just beginning with it, you need to do some extra digging into it to get it right.

Now, if you are holding a rifle in your hands, you can notice the lens there to see the target and shoot. It looks like the one below in the picture.

Remember that it is the most important part of the rifle. The main purpose of the rifle scope objective diameter is to pass the light back to the ocular lens. It provides you with a clear view to see clearly and hit the target.

The other parts that collectively make an objective diameter are the objective bell (It houses the objective lens) and the eyepiece. The eyepiece is the piece that holds the ocular lens.

The ocular lens enlarges the light from the focal point. So, when you look through the scope, the image you see is the light. The scope diameter also has a crosshair and it is to ensure that the shooter shoots the target exactly where it wants to hit.

Understanding the Scope of Objective Lens Diameter

Rifle Scope Different PartsAbove the picture is showing lines and that shows the objective diameter and this is the way to measure it. It defines the amount of light entering the scope as the light. So, it is dependent on the size of the objective lens.

Range of the objective lens: Usually, it is between 32mm and up to 75mm.

However, some of the common questions that might be running in your head are:

  • Should it be bigger or smaller?
  • Can you get more low light use out of a larger lens?
  • Is the bigger is also the brightest?

These are the common questions that people usually ask before trying out the rifle for shooting.

First of all, if the objective diameter is wide, the more light will be transmitted to the scope. It will result in providing the great quality of the image.

By now you have got the idea about the objective diameter. Therefore, now it’s time to move on to the other qualities and main tips to choose the right diameter.

Factors to Consider for Choosing the Scope Objective Diameter

Is it the time of the year to buy a new scope objective diameter? Well, before you get into it, the following are the factors to consider and rely upon.

1. Size of Objective Diameter

The size says it all. It determines the position of the scope, and larger the size of it, the bell objective will also be larger. An increase in the size can provide a clear image and also change your mounting position.

Well, if you are choosing it for a low profile job, you may choose the mid or smaller size of objective diameter.

Why is Size Important?

  • 28 mm or smaller:

It is powerful and provides a low profile mount along with a comfortable cheek and weld method. Also, rifle scopes with 28mm or smaller are cheaper than other larger ones. Moreover, it is used in the military. The drawback is that you cannot use it for long-range hunting purposes.

  • Mid-range: 30-44 mm:

It offers usable exit pupils for low light hunting and also provides a low profile mount. It is considered better than a small range because of the lightweight quality.

  • 50 mm and higher

It is the preferable choice for long-range shooting sessions. Moreover, the larger the size, the better the quality of an image. So, the wider and clear the image is, it provides stress relief to your eyes.

The drawback is that it is heavy and requires higher mounting rings. And since it is bigger in the size, it may catch the dirt and obscure the view for a shooter.

Overall, the size of the diameter should be selected after considering the purpose of the shooting. If you are choosing it for the simple and short sessions, the small or mid-range diameter is good to go.

Otherwise for the long-range, and if you want more light with daylight for versatile shootings, you must choose the bigger size of the objective diameter.

2. Weight

The larger the size the heavier the rifle. Adding up to the objective diameter will directly add to the weight of the rifle. It can be hard to manage for some people.

If it is a concern for you, you can choose the size of the lens around 40mm and you can also buy adjustable objectives to manage the weight of the diameter as per the shooting purpose.

3. Glass Quality

Professional hunters prefer the larger lens because they want a bright and clear image. So, glass quality is the main thing that provides you with the clarity and brightness of the image.

So, to experience a clear image for a great visual experience for shooting, you may want to look for the glass quality.

4. Usable and Large Exit Pupil

It is the circle of light that you can see in the eyepiece if you are only 10 inches away from it. This is the one that gives you a brighter image with a clear view. You can calculate it by dividing the objective diameter (mm) by the magnification.

Now, there are two more important things relevant to the large exit pupil:

  • The Scope

Here is a little tip about the magnification settings. The lowest settings offer a large beam of light and the highest the setting, the smallest is the beam of light. So, if you have experience in it, you already know that larger is really making a point here.

  • The Human Eye

According to the general facts, the human pupil is between 4 mm and maybe 8 mm at the most. And to get these levels of the pupil, you might need to be in the dark for at least 30 minutes.

So, you can say that the brighter image is not only about the size of the objective diameter, but also the human pupil. So, with the large objective diameter, you need better eyesight too.

So, is objective lens size important?

This is a genuine question and you may have understood by now. But just to make it clearer, remember that size of the diameter says it all. And if you are neglecting it for nor good reason, you might be sacrificing the quality of the rifle. It can end up messing with your targets too. So, be careful about it and understand the importance of it for every next adventure.

Common Myths About the Objective Diameter

Well, now we understand the objective diameter along with its many perks. There are some myths about the objective diameter, and we thought that you might want to know about them too.

Larger Main Tube Allows More Lighting Making a Brighter Scope

It seems right at many levels, but we all know that there is a lot more about the rifle than just the main tube. So, the major benefit of a larger main tube is more adjustment to travel.

It allows you to set the accurate elevation for the bullet drop on your long-range shooting sessions. So, the image quality is more dependent on the erector system of the rifle than the main tube size.

Larger the Objective Lens, the Brighter the Scope

It is right, but it is also right that the size is dependent on the magnification range of the scope, so it’s common. So, all you need is the right setting of the magnification along with the size of the diameter and you can have the desired results.

Heavy Rifle Scope is Durable

This misconception is among the many professional shooters too. But if you really understand the structure and other aspects of the rifles, you will understand that heavy rifle will always lack some efficiency.

It is because when you shoot, the rifle releases the kinetic energy and it flexes the scope. And heavy rifles receiving that amount of energy can be damaging. However, the light rifle will make it disperse the energy efficiently, making it more efficient.

You Need High Magnification to Shoot Long Range

It might be right in some situations, but it is not always the best option to choose from. Well, when you enhance the magnification, it will enhance everything else too causing instability at times. So, once you low the magnifications, you may feel more comfortable in managing the rifle and also shooting for the long-range.

Final Words

As for the conclusion, there are things and factors that you must consider while buying or choosing the scope objective diameter. You know it is the most important part of the rifle and your target shooting completely depends on it.

So, choose it wisely and by keeping the purpose of shooting in your mind. Understand your requirements and also try to go against the wind at times by bursting the common myths for good.

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