Your thermal scope is probably going to cost as much as your rifle. It might cost more. It is not a piece of hunting equipment that you want to give buyer’s remorse.
Now, with that said, here are some things you want to make sure you get in your thermal scope, especially if it will be your first.
A Low NETD Rating
This is probably the most important aspect of this short post, because with a thermal scope it’s easy to be seduced by an excellent thermal sensor resolution, or a high display resolution.
While these things are important, if your scope doesn’t have a low NETD rating, the image will still look fuzzy, especially in hot, muggy conditions in which there are a lot of competing environmental factors.
NETD, or noise equivalent temperature difference, rating, refers to how sensitive the sensor is at detecting thermal gradients. The lower the number, the more sensitive the sensor is.
The reason this is so important – as important if not more important than the sensor resolution – is that if the NETD rating is not low enough, the whole image will look fuzzy, especially if there are no high gradients across thermal boundaries – such as when it’s hot, wet, or muggy.
Therefore, by all means pay a premium for a thermal scope with a high-resolution sensor and display, but be aware that without a commensurately sensitive NETD rating, it might not make a big difference.
An Acceptable Detection Range
If you’re really into long-range hunting of furbearers, like coyotes, who, for instance, often won’t give you a close shot anyway, then you need a scope that can deliver.
Let’s say for the sake of argument your scope only has a 500m detection range, and you want to be able to take shots at coyotes farther off, that might not cut it. Plus, you don’t want to gamble on shots that are on the margin of the scope’s limits, anyway.
Rugged, Waterproof Construction
The good news is that most quality thermal scopes will come with an IP67 rating, if not potentially better, that will shield them against both moisture and dust ingress.
The former is an absolute imperative, as the weather is ultimately unknown until you get in the field and you don’t want sensitive electronics that are not waterproof out there in the elements.
Batteries That Can Easily Be Swapped
Many thermal scopes use 18650 or other rechargeable batteries that can easily be replaced in the field, and some of them can be inserted into the battery compartment from either end. Also, some batteries can be hot-swapped, a bonus on long nocturnal hunts.
Simple, Ergonomic Controls
Lastly, you want a scope with basic buttons and simple, ergonomic controls that are easy to manipulate, even with heavy gloves on.
The fewer buttons and controls, and the more basic, the better. Easier will save you trouble in the field, especially if it is really completely black out.
The Correct Base Magnification
One major difference with traditional glass scopes vs Thermal is that most Traditional scopes give you a wide range of magnification with the only compromise being field of view the higher you magnify. Thermal scopes are different in the fact that typically you only get one base mag. When you “Digitally Zoom” the clarity falls apart quickly. For example, if you purchase a 640-resolution sensor with a 2.0 power base mag and digitally zoom the scope to 4 power (2x of the base mag) you lose half of your resolution and now are looking at 320 lines of resolution. Where a 4x base mag. 384 resolution scope that is significantly less money due to the 384 sensor can out-perform the 640 scopes at 4 x base mag.
There are some new technologies available like “OCULAR ZOOM” or “Dual Field of View” on some scopes that allow you to zoom with little loss of image quality throughout the zoom range. Ocular Zoom allows you to zoom in on the screen which significantly reduces degradation of the image, unlike Digital Zoom. Dual Field of View scopes either switch lenses before the sensor or moves the sensor further away from the lens to magnify, one down fall to this method is Dual Field of View scopes tend to have a “Fisheye” effect.
Generally, coyote hunters prefer a higher base mag. then a Hog hunter. Coyotes are much smaller than hogs and you typically try to identify them at further ranges ie. 300 – 400 yards or more. Higher base mag thermal scopes have a smaller field of view but have a sharper image at long distances. Hog hunters generally prefer low base mag due to the size of the target and relatively close nature of hog hunting. Low base mag does not have as sharp of a picture at long distances but gives you a much larger field of view in general. Larger Germanium Lens size also dictates field of view and contributes to better image clarity.
Where to Get Your Next Thermal Scope
Here for a new thermal scope for your rifle? Whether you intend to retire an older model for something newer, lighter and better or this will be your first ever foray into the world of thermal optics, get what you need online at Dark Night Outdoors. They sell a wide range of thermal optics, not just scopes but also thermal monoculars and binoculars, too.
