NHBS Guide to Night Vision and Thermal Optics

There are many scenarios where our attempts to observe and survey certain species are hampered by our limited sensory systems. Many animals are difficult to detect because they utilise cryptic colouration or disruptive patterns, or they have evolved ingenious behaviours to conceal themselves within their environment. In other cases, environmental conditions such as low light levels or fog, can reduce visibility and disguise even some of our most obvious resident species.

Ecologists, researchers and amateur wildlife enthusiasts have overcome these sensory limitations by using thermal imaging and night vision optics. This article will cover how these different technologies function, highlight their key specifications and give recommendations for those looking to purchase one of these devices.

© Dûrzan cîrano

Thermal Imaging

Thermal imaging works by using an electronic detector element to convert the infrared light (heat) emitted by objects in the environment into a visible pattern of colours that vary depending on the temperature of the object. Thermal imaging devices (TIDs) are becoming increasingly common in ecological surveys because, unlike night vision devices, they can produce an image in daylight or complete darkness, even through fog.

When choosing a TID there are a few key technical specifications that you should consider for your project:

  • Resolution – The clarity of the images/videos is determined by the number of heat sampling points. The higher the resolution, the easier it is to spot small animals at a distance.
  • Refresh Rate – Determines how often the screen is updated with a new image. A refresh rate of 30Hz or more is recommended for fast-moving animals such as birds and bats.
  • Zoom – This is particularly useful for larger species identification and counting your target more accurately.
  • Field of View (FOV) – The horizontal and vertical angle of view that you can see through the thermal imaging device. A wider field of view is useful when detecting small animals.
  • Maximum Detection Range – Gives an indication of how far the device will be able to detect a human-sized object effectively.
Pulsar Axion XM38

This thermal monocular has a compact, ergonomic design and features all the excellent capabilities of Pulsar’s more advanced thermal imaging devices.

  • Refresh rate: 50Hz
  • Sensor resolution: 320 x 240p
  • Digital zoom: 2x, 4x
  • Field of view: 5.8° horizontal
  • Max Detection Range: 1700m
  • Video Recording: Yes
  • Streaming capabilities: Yes
  • Price: £2,059.99



See the full range of Pulsar Axion models

Pulsar Helion XP50

A powerful thermal imaging monocular with an impressive resolution and detection range, as well as full remote control through the Stream Vision app on a smartphone or tablet.

  • Refresh rate: 50Hz
  • Sensor resolution: 640 x 480p
  • Digital zoom: 2x, 4x, 8x
  • Field of view: 12.4°
  • Max Detection Range: 1800m
  • Video Recording: Yes
  • Streaming capabilities: Yes
  • Price: £3,949.99

See the full range of Pulsar Helion XP & XQ models

Seek Thermal CompactPRO FF

Designed to be used with a smartphone or tablet these compact thermal detectors can be easily transported and are excellent for impromptu use.

  • Refresh rate: 15Hz
  • Sensor resolution: 320 x 240p
  • Digital zoom: 2x
  • Field of view: 32°
  • Max Detection Range: 550m
  • Video Recording: Yes
  • Streaming capabilities: No
  • Price: £479.95

See the full range of Seek Compact models

Seek Shot

Designed to be used quickly and conveniently, these pocket-sized devices are excellent for obtaining thermal images of species such as bats when they are roosting in crevices and cavities. It is also available in a Pro version which has a greater sensor resolution and field of view.

  • Refresh rate: <9Hz
  • Sensor resolution: 206 x 156p
  • Field of view: 36° horizontal
  • Max Detection Range: 300m
  • Video Recording: Yes
  • Streaming capabilities: Yes
  • Price: £579.95

 

Night Vision

Night vision technology operates either by using an image-intensifier tube (analogue) or an electronic sensor (digital) to amplify the small amount of light present in dark environments to generate a bright image. They typically produce a monochromatic green or greyscale image, however some newer technologies are now able to capture colour images in low light conditions.

There are a few specifications that you should consider when choosing an night vision device (NVD):

  • Viewing Range – The distance to which you can see and distinguish objects using the device can be crucial for certain projects. A low-end NVD will typically have a viewing range of around 200m, while more high-end models can achieve viewing ranges of up to 500m.
  • Analogue Night Vision – These scopes are grouped into generations. Gen 1 scopes are the most economic but have a limited range (approximately 75m), lower resolution and limited field of view. Gen 2 and 2+ scopes offer performance improvements such as longer range, better image resolution and greater field of view.
  • Digital Night Vision – Digital devices typically produce higher quality images than Generation 1 scopes, often have a video output or SD card allowing video capture.
  • IR illumination – Most night vision devices have a built in IR illuminator to increase the brightness of the images it takes, however purchasing an additional IR illuminator may be necessary when working in extreme darkness.
SiOnyx Aurora

New for 2019, this innovative night vision monocular utilises SiOnyx’s Ultra Low-Light Sesnor Technology to record colour footage not only during the day but also in both low-light and night-time conditions. It also features a wifi module to stream or transfer photos and videos, as well as a GPS module to automatically geotag and timestamp recordings.

  • Digital: Ultra Low-Light CMOS sensor
  • Digital Zoom: 1-3x
  • Field of view: 42°
  • Display colour: Colour, phosphor green, monochrome
  • Video Recording: Yes
  • Streaming capabilities: Yes
  • Price: £799.99
Bushnell Equinox Z2

An impressive digital night vision monocular with a high sensor resolution and viewing range of up to 230m. It can take HD video recordings which can be streamed over Wifi using the dedicated Equinox Z2 App.

  • Digital: CMOS sensorDigital Zoom: 1-3x
  • Field of view: 105m @ 1000m
  • Display colour: Colour (in daylight), greyscale
  • Video Recording: Yes
  • Streaming capabilities: Yes
  • Price: £421.00



See the full range of Bushnell Equinox Z2 models

Yukon NVMT Spartan

An excellent gen 1 monocular that has been designed for ease of use in complete darkness. It is operated using only three buttons and features a lightweight and compact body-shell to protect against any damage.

  • Analogue: Generation 1
  • Lens diameter: 50mm
  • Magnification: 4x
  • Field of view: 15°
  • Display colour: Phosphor green
  • Video Recording: No
  • Streaming capabilities: No
  • Price: £235.00


MORE INFORMATION

To learn more about some of these products or to browse our full range of night vision and thermal imaging optics visit our online store at NHBS.com.

If you would like some more advice on choosing a thermal imaging or night vision device contact us via email at customer.services@nhbs.com or phone on 01803 865913.

Collecting visual evidence of bats at roost entrances

Aim
Recording bats and their behaviour around roost entrances can be extremely useful for a number of reasons: as evidence to present to a client, to demonstrate or test for a change in behaviour during or after mitigation, and as a back-up system to record the presence of the quieter bats like the brown long-eared. We tested two night vision systems at a lesser horseshoe maternity roost.

Yukon Stringer 5 x 50 Night Vision MonocularPulsar Quantum S Series Thermal Imaging Scope

Methods

We set up two very different night vision video recorders on tripods near the entrance of a large lesser horseshoe roost near Totnes, Devon. The first was the Yukon Stringer 5 x 50 Night Vision Monocular, a very reasonably priced Generation One night vision device with a built-in video recorder. The second was the Pulsar Quantum HD38S Thermal Imaging Scope, a thermal imaging camera with a 30 Hz refresh rate coupled with a Yukon MPR Mobile Player / Recorder. Both were used to film bats as they emerged from the roost entrance and as they flew around the garage within which the roost entrance is sited.

Results
The two videos below demonstrate close-up and distance footage from both the Yukon Stringer and the Pulsar Quantum:

Video: Surveying a bat maternity roost - Close upVideo: Surveying a bat maternity roost - At a distance

Discussion

Image Quality: The Pulsar Quantum produced some very high quality video that was clear and easy to interpret. The results from the Yukon Stringer are slightly less clear but are still of sufficiently high quality for most purposes.

Usability: The Yukon Stringer does have a much narrower depth of field and due to the fixed zoom it proved very hard to get any decent footage of the bats flying around within the garage space.

Battery Life: The only drawback was the short battery life of both the Quantum and the Yukon MPR Mobile Recorder. To get round this we used the EPS5 External Battery on the Pulsar Quantum and changed the batteries of the Yukon MPR regularly – not the ideal solution but the cheapest way we know of to get some really impressive thermal imaging video.

NHBS Weekly Digest: Snails; birds – extinct, and hidden; 77 Years of WAZA; spotting scopes and hand lenses

New books in stock 

The best of the new arrivals:

Snails on Rocky Shores jacket imageSnails on Rocky Sea Shores

John Crothers

Number 30 in the Naturalists’ Handbooks series. The British and Irish coastlines are covered in this key to the common species. Habitats and ecology are considered along with accessible techniques useful to anyone interested in the study of these fascinating invertebrates. Clearly illustrated throughout with photographs, maps and diagrams.

Extinct Birds jacket imageExtinct Birds

Julian P. Hume and Michael Walters

This Poyser monograph detailing the avian extinctions of the last 700 years is a vital resource for the serious ornithologist as well as the interested amateur. The historical range is fascinating; in the Plovers section, for instance, the Madagascar Lapwing – which disappeared around the 14th century due to habitat aridification, and is known only from subfossil records – rubs shoulders with the Javan Lapwing, which is assumed extinct having not been recorded since 1940 – although an unconfirmed report is given from 2002. Thorough and informative.

RSPB Birds: Their Hidden World jacket imageRSPB Birds: Their Hidden World

Peter Holden

Handy compact guide to the intricacies of avian behaviour, focusing on the usual categorisations of territory, breeding, songs, migration, feeding etc. but incorporating the lesser-known facts and interesting discoveries made through recent scientific investigations. Peter Holden worked for the RSPB for over 40 years and is the author of 9 books, including the RSPB Handbook of British Birds – a bestseller now in its third edition, and the acclaimed RSPB Handbook of Garden Wildlife.

77 Years jacket image77 Years: The History and Evolution of the World Association of Zoos and Aquariums 1935-2012

Laura Penn, Markus Gusset and Gerald Dick

Of interest to anyone associated or involved with zoos and aquariums, or the history of wildlife conservation in general. Tells the story of WAZA, and the key individuals and events involved since its establishment in 1935, through archival material that goes back to the 1930s, giving insight into the various historical contingencies and political and industrial factors that have affected the development of the organisation.

Wildlife Equipment Highlights 

Our recommendations to help you get kitted out for conservation field work, wildlife watching, travel and photography, are selected from our range of over 2,000 equipment items.

Nature Spotting ScopeNHBS are now selling high quality affordable spotting scopes. The first addition to our new range is the Hawke Nature spotting scope with fully multi-coated optics providing crisp, bright images and available with either 20-60x or 24-72x magnification. The Nature family ofGowlland Plastic Hand Lens spotting scopes is designed to deliver years of functional use for the budget-minded consumer. Both Nature spotting scopes are waterproof and come as a complete kit with a hard storage case, soft carry pouch and fully adjustable aluminium tripod.

The Gowlland range of Hand Lenses are another great new addition to our range. With a standard lens and plastic body these affordable lenses are perfect for school groups.