42mm vs 50mm lens - which is the best? (2023)

42mm vs 50mm lens - which is the best?

42mm vs 50mm lens - which is the best? Which is better when it comes to scopes: a 42mm versus a 50mm lens?

Will a 50mm lens give me a brighter image and a wider field of view? These are questions we get all the time. Let's go through the advantages of the 42mm and the 50mm to help you outfit your rifle with the right scope this season.

Just to be clear, the objective lens of a scope is the lens furthest from your eye. In most cases, the objective lens is the largest part of the entire tube body. It plays a crucial role in the amount of light entering the scope. The basic premise around lens diameter is that the larger it is, the more light enters the scope and eventually gets to your eye. And the bigger it is, the better the ability to see detail, as there's a bigger "sweet spot" in the lens itself.

A common misconception is that the 50mm lens offers a wider field of view than a 42mm lens. This is incorrect, the field of view is determined by the design of the eyepiece and has no field of view. A quick way to prove the FOV misnomer is to punch a hole in a business card-sized piece of paper and cover the lens. If you look through the scope you will see that although you limit the size of the lens diameter, the FOV does not change, but the image is much darker. This proves the importance of the lens in collecting light. Here's a short video demonstrating this theory using binoculars.

So how do you know if 42mm or 50mm is best for you? Each lens size has advantages, so it pays to understand the relationship between scope, weapon, and the type of hunt/shootout you intend to undertake. 5 tips to help you make the right choice:

1: Best mounting position 42mm vs. 50mm lens

Why is that important? The size of the lens diameter gives you an idea of ​​how theScope sits on top of your rifle.

Mounting a 50mm scope requires the use of tall mounts in most cases and results in the scope being mounted higher from the receiver, which can cause eye alignment issues and discomfort. A good marksman knows that a low, even weld improves accuracy.

Mounting a 42mm lens allows for a lower profile. You can achieve a consistent cheek seam, quick and easy eye alignment, and purchase and use standard mid-height mounting rings.

(Video) Riflescope 101: Objective Diameter and Tube Size

42mm vs 50mm lens - which is the best? (1)

42mm vs 50mm lens - which is the best? Which is better when it comes to scopes: a 42mm versus a 50mm lens?

JL explains the benefits of the two and why he chooses one for various hunting applications

2: Consider the weight

A 50mm lens typically adds to the overall weight of the scope.

So if weight, bulkiness and weldability are your concerns, you should probably go for the 42mm lens. Especially if you are planning the one-off sheepHunting that requires a lot of hiking... You'll appreciate storing your gearas easy as possible.

If you're hunting whitetail deer from a stand of trees or a box blind and don't mind carrying a few extra grams, upgrading to a 50mm lens might be for you.

Weight comparison of the TORIC riflescope line:

(Video) What Do Different Rifle Scope Objective Sizes Do?

TORIC 4-20x50mm – 34 Unzen

TORIC 3-15 x 50 mm – 22,3 Unzen

TORIC 3-15 x 42 mm – 20,1 Unzen

TORIC 2-10 x 42 mm – 18,6 Unzen

3: Glass Quality / Increased Resolution

Typically, hunters look for larger lenses, believing they will provide a brighter image. Please remember that if you use inferior quality glass, you will end up with a poor quality large lens. This kind defeats the purpose of going to 50mm.

Here are the facts. If high-quality glass is used, a larger lens will provide higher resolution. That means it has the ability to resolve detail in different lighting conditions. Since image quality and brightness are directly related to glass quality and not lens size, you should go with an optical company that uses high transmission glass and superior coatings. This ensures maximum brightness in low-light situations and offers an exceptional visual experience overall.

Therefore, a 42mm scope with exceptional glass will outperform a 50mm lens with average glass in low light conditions and provide a better overall image.

What about the resolution... Can I see more detail? It's true that a larger 50mm lens offers higher resolution. This is partly because a larger sweet spot (center of the lens) is larger than the sweet spot of a 42mm lens.

(Video) The Perfect Focal Length?

42mm vs 50mm lens - which is the best? (2)
The TORIC series uses SCHOTT HT (High Transmission) glass to improve overall light transmission.

4: High magnification

Is it true that a 50mm scope allows the shooter to stay out longer and get better shots in extremely low light than a 42mm scope?

As the sun goes down, your effective hunting range with a powerful optic will become shorter and shorter. However, you need to lower the magnification to get as much usable light as possible. However, a larger lens has advantages when it comes to long-range shooting. Which brings us to the next point about the exit pupil.

5: Light Gathering / Benefits of the Exit Pupil

What is an exit pupil and why is it important when choosing the right lens size for my scope?

The exit pupil is the circle or ray of light you can see in the eyepiece lens if you were about 10 inches away from it. This tells you how much light is being transmitted to your eye. And it can ultimately give you an enhanced and brighter image as you lower the magnification setting. You can see this visually when hunting in low light.

42mm vs 50mm lens - which is the best? (3)As the light begins to fade, decrease the magnification and you will see your image brighten.

The exit pupil can be calculated by dividing the lens diameter (mm) by the magnification.

(Video) Prime Lens Comparison! 24mm vs 35mm vs 50mm vs 85mm vs 135mm

A scope set to its lowest magnification setting gives you the widest beam of light. Conversely, the highest magnification setting gives you the smallest beam of light.

A 3-15x50 scope has an exit pupil of 16.6mm at the 3rd power to 3.33mm at the 15th power (50 divided by 3, then 50 divided by 15).

As you can see at 3x there is a big difference between this window of light and 15x. Does a larger light window correspond to a brighter image in the dark? While it may seem like the bigger the merrier concept is true, there's a limit to how much your eye can take in. Here are the facts:

The human pupil can only dilate between 2mm in bright light and 7mm in total darkness (for healthy adults with good eyesight). So if you have your scope set to its lowest magnification and have an exit pupil of 16.67 or pretty much anything larger than 8 or 9mm, all that light is wasted. It's not profitable since your eyes can't use it at all.

For example, a 3-15x50 TORIC at 10x gives an exit pupil (light window) of 5mm. This 5mm exit pupil is very useful in low light situations for hunters who need to see detail at 10x magnification. A 3-15x42 at 10x has a window (exit pupil) of 4.2mm - still great for hunters. But if you start increasing the magnification to 12x, for example on the 3-15x50 = 4.1 and 12x on a 42mm scope = 3.5. Now it's starting to go under 4mm, which is difficult to use in low light. For more flexibility when using higher performance optics, especially in low light conditions, a 50mm lens is your best bet.

Another advantage of a large exit pupil is that you can see through the scope more flexibly. And you can get to your destination quickly. You can finish fast when the big bucks unexpectedly come into your sights. Snipers have the luxury of finding that spot on with a 2mm exit pupil. But hunters will appreciate the freedom to be just right even when your eye isn't perfectly aligned on the optical axis.

Conclusion – advantages of a 42mm and 50mm lens

Benefits of 42mm scopes

  • Offers a lower mounting profile
  • Enables a sufficient and comfortable cheek seam
  • Good exit pupil size for close to medium range hunting in low light
  • Lightweight and compact, weighing only 20 ounces
  • The smaller size allows for better accessibility in and out of gun sheaths or ATV cases

Advantages of a 50mm

(Video) 5 Reasons 40mm is the Best Focal Length

  • Efficient for a long timerange shooting
  • Good exit pupil size for longer range shots in low light
  • Improved image quality and higher resolution in low light conditions
  • Ability to use higher magnifications longer when available light diminishes
  • Flexibility to find the sweet spot faster with a larger exit pupil

Get the "right size"

To determine which lens size is best for you, you must consider what type of hunting or shooting you will be involved in. If you are looking for a more versatile and all-round scope that does its best in any light, terrain and hunting situation, then a 42mm lens size is probably best suited.

But for those who want to maximize the potential of light-gathering capabilities in any daylight, a larger objective diameter lens offers more light than you can use, as well as some additional benefits.


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