A Beginner’s Guide To Thermal Imagers

A good pair of binoculars or a spotting scope are excellent tools for observing birds and other wildlife, but it will come as no surprise that there are plenty of denizens of the countryside that are incredibly hard to spot with normal optics.

That’s where thermal imagers come in.

With a longer detection range than infrared technology, thermal imagers are fast becoming the most popular tools for observing the smaller, better-camoflaged wildlife that normal optics struggle to reveal. Not only that, but whereas infrared optics are limited to nighttime only, thermal imagers can be used day and night, thus adding to the versatility.

But what are the key features to look for?

First of all you need some idea of the detection range that the imager will give you. Cheaper units usually have shorter detection ranges, though this can be useful in itself if you know exactly what you’re looking for – if you don’t, then it helps to have an imager with a longer detection range to provide a more versatile product. Most product listings will give the range in metres and a lot of them use a human as the standard reference “animal”.

Secondly, you also want to know the temperature range/resolution of the device’s monitor. Sharper resolutions cost more, but they give you extra detail in your image and can be the difference between a vague guess at what you’re seeing and a confident ID. A better temperature range will make things easier, too.

A wide field of view, as with binoculars and monoculars, improves your image by giving you a larger image to look through when you’re trying to spot a well-hidden bird or animal.

And, finally, there’s the NETD rating.

NETD stands for “Noise Equivelant Of Temperature Differential” (now you know why we use the abbreviation!) and provides a guide to the sensitivity of the imaging sensor. A lower NETD number means a more sensitive sensor.

Why is this important?

Well, put simply, a device with a more sensitive sensor will be better able to seperate thermal signatures. Imagine you’re outside on a hot sunny day (we do occasionally have them in the UK) and you want to see if there’s anything in the long grass in the distance. First of all the ambiant air temperature will be high and, as a result, the grass itself will be nice and warm. If there’s anything hiding there, its body temperature is also likely to be quite high. All this can result in a messy, indistinct image that doesn’t tell you anything useful. But, with a lower NETD rating, and therefore better sensitivity, your imager will be able to seperate these thermal signals and provide a much clearer image and making the difference between seeing nothing and spotting that elusive bird you’ve been searching all day for!

Naturally, there are quite a range of optics to choose from, and you can visit our listings pages to see our full stock.

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  • Pulsar Axion 2 XQ35
  • Hik Micro Gryphon Thermal Fushion Imager
  • monocular-imaging-thermal-imaging-Grovers
  • Thermal imagers as monoculars & binoculars by leading manufacturers Hik & Pulsar
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