Thermal Spotting Scopes: What to Buy and What the Law Says

Resolution, pixel pitch and lens. Three numbers on the spec sheet matter most. Sensor resolution is the pixel count: a 640x512 sensor has 327,680 pixels, nearly three times the 110,592 of a 384x288 sensor, so it draws a more detailed picture of the same view. Pixel pitch, usually 12 or 17 micrometres, is the size of each pixel; a smaller pitch lets a maker fit a smaller, lighter lens for the same field of view. Lens focal length sets how much of the scene you see and how big a distant animal looks.

Lens and field of view in practice. HIKMICRO's FALCON 2.0 monoculars share a 640x512, 12 micrometre sensor. The FALCON FQ35 2.0 has a 35 mm F1.0 lens and a 12.5 by 10.0 degree field of view, 21.9 m by 17.5 m at 100 m. The FALCON FQ50 2.0 has a 50 mm F0.9 lens and an 8.8 by 7.0 degree view, 15.4 m by 12.2 m at 100 m. The longer lens shows more of a distant animal but covers less ground at once, so a hedge line takes longer to sweep. Neither is better. Woodland rides and close ground suit the wider view; open fields and long sight lines suit the narrower one.

Detection is not identification. HIKMICRO quotes a detection range of 1,800 m for the FQ35 2.0. The FQ50 2.0 is quoted at 2,600 m. Those figures are the distance at which the unit can pick up a warm target of the size the maker assumes. They do not tell you how far you can recognise a fox rather than a badger, or a roe doe rather than a muntjac, and the recognition and identification distances are far shorter. Treat the headline range as a ceiling in good conditions. Work out how far you need to identify quarry and its surroundings for a safe shot, and buy for that.

Sensitivity and British weather. NETD, in millikelvin, is the smallest temperature difference the sensor can show, and lower is better. Both FALCON 2.0 models list less than 15 mK. It matters most on warm, damp nights when a fox is only a few degrees warmer than wet grass. Thermal works in total darkness, but rain, fog and humidity absorb infrared and cut range, so expect less than the spec sheet on a drizzly night. Both models are rated IP67, which means dust-tight and protected against temporary immersion.

Refresh rate, weight and battery. A 50 Hz refresh rate, as on the FALCON 2.0 pair, pans smoothly; lower rates smear when you sweep across a field. The FQ35 2.0 is listed at 485.5 g with battery, which matters on a long walk-in with the unit around your neck. Its replaceable 21700 battery is listed at 6.5 hours or more at 25 degrees C with Wi-Fi and the zoom feature on. A winter night is colder than that test, so carry a spare cell.

Handheld thermal or thermal sight. A handheld thermal does not replace a thermal sight, but it makes one more useful. It tells you something warm is there. Telling a roe buck from a doe, or checking an animal is the one you intend to cull, often needs daylight glass or a closer look. If you already own a quality day scope and plan to shoot at night, a front clip-on is the other route; our night vision add-on guide covers how those fit.

Air rifles. A thermal spotter finds the quarry; it does not extend the rifle. Sub-12 ft/lb air rifles, springers included, are effective only to about 50-75 yards on small quarry such as rats and rabbits, however far the spotter can see.

UK law, checked 5 November 2026. Owning one: the Home Office licensing guide lists the component parts of a firearm that need a certificate as a barrel, chamber or cylinder; a frame, body or receiver; and a breech block, bolt or similar mechanism at the rear of the chamber. Optics are not on that list, so you do not need a firearm or shotgun certificate to buy or own a thermal spotter in England, Wales or Scotland, or to use it for watching wildlife.

Deer at night. The night-shooting offence concerns taking or killing deer, not watching them. In England and Wales, section 3 of the Deer Act 1991 makes it an offence to take or intentionally kill a deer between the end of the first hour after sunset and the start of the last hour before sunrise. The exceptions include a licence from Natural England or Natural Resources Wales for public health or safety, conserving the natural heritage or preventing serious damage to property; a notice under section 98 of the Agriculture Act 1947; and killing a deer at night to prevent the suffering of an injured or diseased animal (section 6(2)), which is where a thermal spotter helps with finding a deer after a shot. In Scotland, section 18 of the Deer (Scotland) Act 1996 makes it an offence to take or wilfully kill or injure deer at night, with night shooting allowed only under NatureScot authorisation.

Other quarry. Rabbits, hares, foxes and wild birds each have their own rules for night shooting, and section 5 of the Wildlife and Countryside Act 1981 bars "any sighting device for night shooting" for killing or taking wild birds, so a thermal sight is a different matter from a spotter. Our night vision add-on guide goes through the quarry rules. Northern Ireland has separate legislation and is not covered here. None of this is legal advice: for your own case, ask BASC or your force's firearms licensing department.