How Objective Lens Affects Shooting?

You have been in various hunting expeditions but when you are just about to hit the target and get a clean shot, you miss by a few inches. So you ask yourself, what could be the problem? Have I not bought the right riflescope? These are the questions that keep swirling up on your mind.

Well, worry no more; I have got the solution to your troubles. The key aspect of a scope is the objective lens.Then comes the next question. What is an objective lens and how does it relate to shooting?

An objective lens is a lens at end of a scope and closest to the object that is being viewed.When buying or acquiring a scope, you may come across this numbers 3–9x 40mm.The 3–9x represents magnification and the power of the lens. The 40 mm represents the objective lens diameter.

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Objective Lens and Light Gathering

The main purpose of an objective lens is to gather light in order to provide you with a bright and vivid image.This implies that the bigger the lens the more the light filtrates through the scope. However, there is a mitigating factor to consider which is the human eye. The human eye uses the pupil to detect and take in light.

The pupil dilates from 2mm up to 9mm for a person with a perfect human eye. But for the average middle-aged person, the pupil dilates from 4mm to 8mm. During the darkest of the nights, the pupil dilates up to 9mm. This enables people with perfect eyes to see better in the dark by giving them a natural night vision. The pupil reduces to 2mm for the average person to avoid one being uncomfortable in brightest of days.

For the objective lens to attain maximum light filtration, the exit pupil of the scope should match your human pupil.This means that a person will not see a clear image when there is a great difference between exit pupil and dilation of the human pupil.Magnification affects both the exit pupil and objective lens.

Having a great magnification in a small objective lens will make the image to appear dark and dim.To determine the exit pupil size, we divide the scopes diameter by the magnification level.Getting the size helps in matching it with dilation of the human eye.

Choosing a Large Objective Lens

When choosing a large objective lens we have to analyze various aspects. The main theme will be its benefits and the drawbacks. The benefits include:

· Useful for long range and extra long-range shooting or hunting

· The field-of-view is brighter and wider

· Offers better flexibility with larger exit pupil

· Higher magnifications in low light conditions

· Image quality is improved at larger magnifications

· Suitable for hunting at night

· The drawbacks for using a larger objective lens include:

· More expensive compared to scopes of similar quality

· They are heavier making off- hand shooting more difficult

· Mounted higher and farther from the barrel which decreases overall precision and accuracy

· Risk of losing proper cheek and weld positioning

· Collects dirt in harsh weather conditions

Another consideration to make while choosing a large objective lens is checking the size of the objective lens bell. An objective lens bell is that metal housing, which surrounds the objective lens. It serves as a protector to the objective lens. This objective lens bell is responsible for causing mounting interference. To evade the interference, having a concave objective lens bell will make it easier for you to mount a scope with a larger objective lens.

Those having visual impairments such as optical focus injuries and lazy eye may find a larger objective lens suitable to them. This is because the large optical lens covers their inability to focus. The quality of their hunting is improved by the use of a large objective lens.

Glass Quality Matters

While choosing the right scope, you have to take into account the glass quality matters. Superior scopes with high-quality glass will outperform those scopes with poor quality glass. Medium scopes with superior glass coatings that minimize refraction will also outperform large objective lens scopes.

Cost becomes a great determinant of performance in choosing the right objective lens. Advancements of filters and coatings make one to choose higher quality glass instead of a larger sizing. This is because the objective lens has polarization and anti-reflecting coatings.

If you acquire an objective lens without built-in polarization, there are companies which can fit the filters onto your scope.The improvement in light filtration with high-quality glass will enhance the quality of your sight.

Get the Right Sized Objective for the Job

Evaluating the type of hunting or shooting one involves in will determine the right sized objective lens. For those looking to go for pellet shooting or plinking on a Saturday afternoon, a rifle scope with a small objective lens allows you to hunt at close range.

The objective lens provides enough light filtration enabling one to get a clear mark on every shot. A small objective lens has a lens diameter of 28mm and below to distinguish from the rest. Medium objective lens is suitable for those who are looking for an all-purpose rifle scope that does well in any hunting conditions, terrain and light conditions.The popular models are 3–9x40 and 2.5–10x40. But in case you still haven’t decided a 3–9x36 and 4–12x44 will serve the same purpose.

The mid-range objective lens diameter range from 30mm to about 44mm. For those who want to maximize light filtration, a large objective lens is suitable for this purpose. The large objective lens works well at night and low light conditions. These lenses have a diameter of 50mm and above. If one considers an objective lens that suits their eyes, then a 6x42 scope will be the best to have.


While choosing the best rimfire scope, the objective lens is the most important consideration to take into account.Other considerations are your eyesight, hunting conditions, hunting styles and weight.

The quality of hunting will be based on what you choose to work with depending on your capabilities and proper light conditions. Having the right scope within your budget will serve you well and there is no harm in getting your hands on other scopes to gain more experience.