General features of thermal clip-ons

Thermal imaging is gaining popularity since it offers great advantages for night-time observations. Especially the clip-on devices are widely used since clipping of the device on the objective bell of the day time optics is very simple and fast.

The main advantage of thermal clip-on´s

• Transforming day optics into a thermal optics, which keeps the point of impact on the same place.
• The user can also use the same rifle scope, on which he is trained, with the same reticle, which can still be used for bullet drop when shooting on longer distances.
• A thermal clip-on device can also be used on other optics such as binoculars and monoculars, only for observing purposes.

Thermal clip-ons compared to stand-alone thermal rifle scopes

Usually, thermal clip-on devices have a lower sensor resolution when compared to thermal rifle scopes, but clip-on´s offer all the usability of the normal scope. This is especially handy when using the same rifle for daytime hunting and hunting in the night.

• The shooting position stays the same due to the longer eye-relief and does not change as if you would mount a thermal rifle scope.
• Attaching a thermal clip-on device is also much easier than changing the entire scope on the rifle, which can sometimes cause also a point of impact change.
• Whatsoever, a bit of the optical performance gets lost, but this is minimal and, in most cases, it is not noticeable.

Thermal clip-on´s are allowed for purchase in many EU countries where stand-alone thermal optics are not allowed. The price is also lower than the price of thermal rifle scopes, which makes them also more interesting for many hunters.

Thermal clip-on devices compared to night vision clip-on devices

There are many advantages but also the disadvantages of thermal clip-on devices against night vision.

• The main advantage is the much easier detection of animals even in complete darkness,
• and detection on much longer distances.

This is especially noticeable if the animal is in the forest behind dense vegetation – with a thermal clip-on device these animals are easy to see and almost impossible to see with a night vision device since the vegetation reflects the IR light from the illuminator. With a night vision device, only the eyes from the animal can reflect some light if it looks straight towards you.

Here we get to another advantage of the thermal clip-on device – it does not need any additional IR light in complete darkness. A night vision device does if there are no light sources in the area (moon, stars, road lighting, etc.). An additional IR light can, whatsoever, be visible for some animals, so they get scared and can run away if an IR light under 850nm is used.

With the thermal clip-on colder objects are more difficult to see, such as small trenches and grass. So, if you are not very cautious about colder objects in front of the target, the bullet can hit the obstacle and consequently miss the target. Also, the antlers on the animal are not well visible, so evaluating the game can be very challenging or not even possible. With a night vision device, if the animal is not too far away and the weather conditions are good, it is possible to see the antlers perfectly.

In bad weather such as rain and mist, it is almost not possible to hunt with a night vision device. The rain and mist reflect the IR light, so you can´t get a clear picture. With a thermal clip-on device, the picture has less contrast, but animals are still clearly visible even at great distances.

Because of the flash when the shot is fired, the picture on an analog night vision device can get white for a short time, so it is almost not possible to spot the target after the shot. With a thermal clip-on device, this effect lasts only a fraction of a second, so spotting the target is much easier. Even if the animal runs into dense vegetation, it can still be tracked with a thermal device. In most cases, even the wound can be detected, so the user can immediately tell if the shot placement was good.

Many thermal imaging devices have also the feature to take photos and videos. Analog night vision devices do not feature this function, but all digital night vision devices do. The resolution in analog night vision devices is much better, and they also drain less energy than the thermal devices.

Adapters for thermal clip-ons

There are several manufacturers that produce mounts for thermal clip-on devices. The most known company in the EU and the first one that started with such production was Rusan, but also SmartClip adapters are very popular.

• The quality of such an adapter has to be good because it is the only part that holds the clip-on device to the daytime rifle scope.
• With a low-quality adapter can happen that the point of impact changes after attaching the device, so it makes sense to invest in a high-quality adapter.

These adapters are available in all different sizes, to perfectly match the objective diameter of all common daytime rifle scopes, for a tight and firm fit. For Pulsar Core devices, there is even a special interface that converts Pulsar's standard bayonet into a thread identical to Dedal's devices.

Buying Guide: What to Look for in a Clip-on Thermal Scope

Generally, you'd look for the same things in a thermal scope that you look for in a clip-on thermal scope. Here are the most important ones.

Compatibility
Make sure the clip-on is compatible with your day scope. Size is not really an issue. Clip-on thermal scopes are designed to go with a wide range of day scope lens sizes.

The most important thing to check is magnification. Manufacturers of clip-on scopes will recommend the minimum and maximum zoom of the day scope you can use the clip-on with.

Optics
The most important thing is the thermal capability of the clip-on. How far can it be? How good is the resolution? Can you zoom?

Thermal resolution: 384x288 is the recommended minimum for a clip-on thermal scope. With this resolution, image quality is pretty good, and you can detect animals as far as 500 yards. A 640x480 clip-on scope will let you see as far as 1,000 yards, and image quality is excellent for more money.
Objective lens size: Get a clip-on with a minimum 50mm objective lens. 50mm is great for close and mid-range hunting. If you do a lot of long-range hunting, get a 75mm or 100mm lens.
Zoom: Most thermal clip-on offers up to 4x zoom, with pricier models going as high as 12x. This zoom can be digital zoom only or a combo of optical and digital zoom. The latter is better if you want to zoom in without making the image all grainy.

Refresh rate: We highly recommend a 60 Hz refresh rate for hunting instead of a lower 30 Hz frame rate. It eliminates lag when you are moving or tracking a moving animal.

Size and Weight
A compact and lightweight clip-on is not just good for portability; it also ensures you don't make your rifle too heavy, affecting balance and accuracy.

If your day scope is already on the heavier side, look for a lightweight clip-on thermal scope.

Display
A bright and crisp display is important to easily detect and track animals. We recommend getting a clip-on with a display resolution of at least 640x480. For even better viewing, get an HD display with a higher resolution of 800×600, 1024x768 or higher.

As you check the display, check whether you can adjust the brightness of the display and change color palettes of the thermal image.

Battery Life
Most clip-on thermal scopes provide around 4-5 hours of battery life using a pair of CR123 batteries. If you want more battery life, your best option is getting an external battery pack.

Check if the manufacturer sells a compatible battery pack separately.

Video Out
Unlike full-size thermal scopes, most clip-on scopes don't have built-in video recording and streaming. The best alternative they offer is to connect an external digital video recorder (DVR).

If you'd like to record videos of your adventures, make sure the thermal clip-on has a video out option.

Waterproof
We highly recommend buying a waterproof thermal clip-on. This ensures you can keep hunting through rain and snow. You also don't have to worry if the scope accidentally falls in the water.