When it comes to retrofitting your rifle with a scope for a precise, hassle-free shooting experience, the layman’s advice would probably be bigger is better, and Hollywood certainly subscribes to this school of thought. But a true gun aficionado would tell you that objective lens size is not always directly proportional to performance – each number on the scope corresponds to a different measurement, and bigger is not always better. It all depends on how you use the riflescope you have. There are ways to get the most of lower diameter lens scopes, especially those of high quality engineering such as the medium size lens diameter ZeroTech riflescopes Thrive and Vengeance models.
This guide will attempt to clear up any confusion over what the different measurements on a riflescope mean, and how they affect the different size ranges of riflescopes you can purchase.
What are the Numbers on my Riflescope?
The numbers that are provided with your riflescope generally give you the magnification range, objective lens diameter, and main body tube length. For example, for the ZeroTech riflescope Trace R3 3-18×50, 3-18 denotes the magnification range – or that the image will appear at a distance ranging from three times to eighteen times closer than to your naked eye. The riflescope’s objective lens size diameter is 50mm, putting it on the larger size classification of scopes.
At higher magnification ranges the scope transmits less light to your eyepiece, but a larger objective lens can transmit more light. Therefore, the ideal magnification range and objective lens usually go hand in hand and different scope manufacturers use these measurements to fashion their products for very specific types of shooters, so pick based on your personal hunting preference first and foremost.
The main body tube length is included with the specifications and in this case it is a standard 30mm. A common misconception is that a greater tube length allows for greater light transmission, but this in fact depends on the size and quality of your objective lens. The bigger tube length does allow for a greater range of elevation and windage adjustments, but does not strictly mean more light.
Keeping these basics in mind, let’s go over the different objective lens sizes available in the market and what they’re best used for.
Small Objective Lens Size (<28mm diameter)
Don’t discount the smaller objective lens sizes too quickly – they’re often manufactured for highly tactical kinds of shooting and are very popular among users in the military. Their magnification ranges usually run on the lower side but using a riflescope with high quality glass more than makes up for it, as it gives you ample light transmission despite the small exit pupil size. In terms of construction, these scopes are the most lightweight and compact options for shooting on the go quickly, using a smaller tube size that makes for easy mounting and a good cheek weld. There’s also less chance of light reflecting off the lens and exposing your position, hence why it’s a popular choice for tactical shooters.
The cons, however, are pretty obvious; scopes of these construction tend to be low power in elevation and windage adjustments, and they’re best used for close range hunting with rifles that offer little to no recoil. But if that’s your hunting preference and your first priority is quick and easy shots that maintain their accuracy with time, then you can save on money and weight carried around by investing in a smaller objective lens size riflescope.
Medium Objective Lens Size (30-44mm)
These are the most common objective lens sizes available in the market, with several options in the ZeroTech riflescopes range including the Thrive 3-9x40mm ZEROPLEX, Thrive 3-9x40mm PHR 3, and Vengeance 3-12x40mm ZEROPLEX, among several other available models. This is usually the most popular size amongst all-purpose shooters because it’s compact while not being too small, not too large so you have a good depth of field, and when mounted sits nice and snug atop the barrel. All in all, it’s a great in-between size that’s perfect for if you’re indecisive on what type of hunting you plan to do and still want to shoot in relative comfort.
The only downsides that you may find with medium objective lens size is they may not be as useful in low light shooting conditions as the larger sizes, and their effective useful range is smaller. But this is where glass quality plays a key role, and with high-quality lenses and optics design like ZeroTech, you can ensure you do not have to compromise on light transmission when going for a medium size lens.
Large Objective Lens Size (>50mm)
Finally, we come to the largest objective lens size available in the market, usually preferred for more extreme shooting situations including night vision or low light shooting, and backcountry hunting. These areas are best suited to the top shelf of ZeroTech riflescopes, including all models in the Trace, Trace Advanced and Thrive HD ranges. This is usually where dealers tell you bigger is better, and some lenses can go up to 75mm, but this is generally regarded as overkill and unwieldy to use. The larger lens sizes guarantee you more light especially at lower magnification, and reduce parallax error as you turn the magnification up. It’s no surprise then that it’s so popular among hunters.
The only downsides come when paired with your rifle, in that they can be on the bulkier and top heavy side and may be impractical to carry around on long distances. They also need higher mounting rings which may affect eye alignment. But if size is no bar to you and you’re game for a high-quality outdoor experience, look no further than a 50mm riflescope with the pinpoint accuracy and rugged engineering of the ZeroTech range.
