Complete Guide to Thermal Imaging Cameras

What Is a Thermal Imaging Camera?

A thermal imaging camera is a device that captures images in the infrared spectrum. They are also known as infrared cameras, thermal scanners, thermal imagers, thermographic cameras, or FLIR cameras.

Infrared (IR) radiation refers to wavelengths on the electromagnetic spectrum that are longer than visible light. In the same way you cannot see radio waves, you can't see infrared with the naked eye.

Said in more words on Wikipedia:

"Infrared thermography, thermal imaging, and thermal video are examples of infrared imaging science. Thermographic cameras detect radiation in the long-infrared range of the electromagnetic spectrum and produce images of that radiation, called thermograms. Since infrared radiation is emitted by all objects with a temperature above absolute zero, thermography makes it possible to see one's environment with or without visible illumination."

Where infrared sits in the electromagnetic spectrum.

How Do Thermal Cameras Work - Key Specifications

Thermal imaging camera specifications are a bit overwhelming if you are unfamiliar with them. Here are some of the details to look out for when purchasing a thermal camera:

Thermal Camera Resolution

Thermal or infrared resolution indicates the detail captured by the thermal detector. For example, '160 x 120' means the thermal camera has an array of 160 x 120 sensors or pixels that create its baseline thermal image. A higher thermal resolution provides more clarity, so more is better.

As thermal resolution increases, thermal camera images gain clarity (and cost!). Top-left = 60 x 80 (eg. FLIR TG165-X), Bottom-right = 640 x 480 (eg. FLIR E96). Note: these images show a raw thermal image before any image enhancements like FLIR's MSX technology have been applied.

Thermal Imager Sensitivity

Thermal sensitivity defines the minimum temperature difference an infrared camera can detect. It is also called the Noise Equivalent Temperature Difference (NETD).

In this case, a low number is better for most applications. For example, pest control or building inspectors gain performance with a lower thermal sensitivity. This is because the temperature differences between building elements with problems, such as higher moisture content, can be quite small. On the other hand, thermal sensitivity is less important if your work involves detecting large temperature changes.

Thermal Imaging Field of View (FoV)

Field of View (FoV) describes the angle at which a camera 'sees' a given scene. Most entry-level thermal cameras have a wide field of view, suitable for thermal inspections close to the object of interest. They can still measure far into the distance - just less accurately than cameras with a narrow field of view.

Field of View is the angle of the thermal imaging camera's lens. Instantaneous Field of View (IFoV) describes the dimensions of one thermal pixel in your target scene.

Infrared Camera Temperature Range

Temperature range or scale is the range of temperatures the thermal camera is calibrated for and capable of measuring. It's an important specification to check if you intend to measure high temperatures such as boilers, kilns, or furnaces.

A Caveat on Specifications

As with many technical products, specifications tell only part of the story. FLIR - the brand we sell - is the undisputed global leader in thermal imaging technology. This shows up in the quality of the devices they sell and the images they produce. It is possible to purchase thermal imagers from brands like SEEK Thermal, which have similar specs but far inferior output.

Choosing a Thermal Camera - Quick Selection Guide

With the above specifications and your available budget in mind, you can select the most suitable option from our range. Here's a summary of available models, roughly ordered by buy price (from lowest to highest):

Model	Thermal Res.	FoV	Max Temp	Sense
One Pro LT	80x60	55°	120°C	0.1°C
One Pro iPhone	160x120	55°	400°C	0.07°C
One Pro USB-C	160x120	55°	400°C	0.07°C
One Edge	80x60	54°	120°C	0.07°C
One Edge Pro	160x120	54°	400°C	0.07°C
FLIR TG165	60x80	66°	300°C	0.07°C
FLIR TG267	160x120	57°	380°C	0.07°C
FLIR C3-X	128x96	54°	300°C	0.07°C
FLIR C5	160x120	54°	400°C	0.07°C
FLIR E5 Pro	160x120	33°	400°C	0.06°C
FLIR E6 Pro	240x180	33°	550°C	0.05°C
FLIR E8 Pro	320x240	33°	550°C	0.04°C
FLIR E54	320x240	24°	650°C	0.04°C
FLIR E76	320x240	24°	650°C	0.03°C
FLIR E86	464x348	24°	1500°C	0.03°C
FLIR E96	640x480	24°	1500°C	0.03°C

Note 1: All thermal scanners above include FLIR's patented image enhancement technology 'MSX'. This sharpens the raw thermal image's appearance on all models by integrating a visual image with the thermal image.

Note 2: The FLIR Exx Series E76, E86 & E96 can have their resolution further improved by a factor of four using software. They also have interchangeable lenses and a choice of 14°, 24°, or 42° lenses in the base kit (24° lens shipped as standard).

Infrared Cameras - Example Uses

As an online store specialising in energy efficiency, our initial interest in thermal imaging was for conducting energy audits. This includes detecting overloaded electrical circuits, draughts, and missing insulation. We soon discovered that uses for thermal cameras go well beyond this niche.

Here are some of the applications and use cases we have encountered.

Thermal Imaging Cameras for Electricians, Technicians & Engineers

Our most common customer application is the inspection of electrical issues. The most popular choice for electricians is the FLIR E6 - although this can vary based on the type and frequency of work. Electrical applications include:

• Hot or Loose Electrical Connectors. Thermal cameras help find defective connections or 'hot joints' before they cause irreversible damage to equipment or stock (eg. in cool rooms).
• Phase Supply & Power Usage. Thermal imaging cameras highlight unbalanced phase supply (electrical load).
• Underfloor Heating. Thermal scanners can show if electric underfloor heating is working properly and/or where a defect has occurred.
• Overheated Components. Overheated electrical components all show up very obviously in the infrared spectrum. Higher-end thermal cameras with adjustable lenses such as the FLIR E96 are the preferred choice of electricity utilities and others to quickly check overhead power lines and transformers for defects.
• Solar Panels. Infrared cameras show up electrical defects, micro-fractures or 'hot spots' in solar PV panels.
• PCB Defects. Technicians and engineers can check for electrical defects on printed circuit boards (PCB's). Check the minimum focal distance if you are interested in this application.

Positions 41 to 43 on this electrical switchboard have an elevated temperature - indicative of high current draw. This image was taken with a One Pro for iPhone during an energy audit.

A thermal image of a solar module showing a problematic and overheated solar cell.

Infrared Cameras for Builders, Plumbers, Architects, Designers & Inspectors

• Leak Detection. The source of a water leak is not always obvious, and they can be expensive or destructive to locate. For this reason, many plumbers have purchased our thermal cameras to make their job much easier.
• Moisture, Mould & Rising Damp. Infrared cameras are used to find the extent and source of moisture ingress into buildings.
• Restoration & Rectification. IR cameras can also determine if restoration works have effectively solved the initial moisture problem. We have sold many thermal imaging cameras to building inspectors, carpet cleaning, and mould-busting companies for this purpose.
• Insulation Defects. Thermal scanners can review the effectiveness of, and find gaps in all kinds of insulation materials. This ranges from home insulation (wall, ceiling and floor) to cool rooms and boilers.
• Air Leakage. Thermal imaging shows up all kinds of air leaks. This includes in air conditioning or heater ducting, as well as around window and door frames and other building elements.
• Thermal Performance. Analyse the performance of heating systems including hot water tanks, wood fires, and electric heaters. Or, evaluate the relative performance of different building components such as glazing and window coverings.
• Waste Heat. Waste heat equals wasted energy. Thermal cameras can help determine which appliances are generating the most heat and wasting the most energy.
• Insurance Claims. Thermal camera inspections are often used as evidence for insurance claims or to maintain insurance coverage.

Missing ceiling insulation as seen with an FLIR E8 thermal camera.

An image taken during an energy audit showing defective insulation in a freezer room.

Thermal image showing a water leak (likely from neighbour above) in an apartment kitchen. All of our thermal cameras take both a visual and thermal image so it's easy to see what area of the building you were looking at.

Thermal Cameras for Mechanical Inspection & Preventative Maintenance

Thermal cameras are used extensively to inspect mechanical systems. Some popular uses include:

• HVAC Inspection. Thermal imaging is used to check heating, ventilation and air conditioning (HVAC) equipment. This includes the coils and compressors on refrigeration and air conditioning systems. It can also help review the heat flows and heat sources within a building.
• Pumps, Motors, Bearings & Conveyor Belts. Thermal cameras can detect overheating mechanical equipment before they cause an expensive failure.
• Welding. With a thermal camera, it's possible to see how temperature varies across and along the weld.
• Vehicles. Infrared cameras can demonstrate specific mechanical issues, such as engine parts with uneven temperatures and exhaust leaks.
• Hydraulic Systems. Thermal imagers can identify potential failure points within hydraulic systems.
• Aircraft. Applications include the detection of fuselage de-bonding, cracks, or loose components.
• Pipes & Ducts. Thermal scanners can identify blockages and leaks in ventilation systems and pipework.
• Non-Destructive Testing. Infrared non-destructive testing (IR NDT) is a valuable process for detecting voids, delamination, and water incursion in composite materials.
• Hydronic Heating. Thermal imagers can check the performance of in-slab or wall-panel hydronic heating systems.
• Greenhouses. Commercial greenhouses (eg. plant and flower nurseries) use infrared vision to review temperature control.
• Tank Levels. Petrochemical companies and others use thermal imaging to validate the liquid level in large storage tanks.

High-clarity thermal images have higher resolution. Generally speaking, the more you pay, the better the image quality you get. The above is an example image from a camera similar to our FLIR E8 or higher in performance.

Thermal inspection of hydraulics on mining equipment. If you are taking images of objects that are far away, we generally recommend the Exx Series as they have high resolution and a narrower field of view.

Thermal Scanner Uses in Safety & Law Enforcement

We've sold thermal imaging cameras to the Australian Defence Force, State Police Forces, and Rural Fire Brigades all around Australia. Applications include:

• Fire Fighting. In particular, 'mopping up' after bushfires and back-burns. Thermal cameras show up hot stumps and other issue that may re-ignite a bushfire.
• Search & Rescue. Thermal imagers have the unique benefit of being able to 'see through' smoke.
• Detecting Illegal Activity. Whether it be burning wood without a permit, or growing drugs in the roof, thermal scanners can easily spot any area with irregular temperature profiles.
• Preventative Maintenance. Regular inspections with thermal imagers can reduce the risk of fire or premature product failure.
• Public Health. Our high-end thermal cameras can detect fevers or 'elevated body temperature'. Use cases include the SARS, H1N1, and coronavirus (COVID-19) pandemic.
• Counter-Surveillance. Covert surveillance equipment such as listening devices or hidden cameras all consume some energy. These devices give off a tiny amount of waste heat that is clearly visible on a thermal camera (even if hidden inside or behind an object).

An infrared camera system scans passengers for elevated temperature at an airport.

Thermal image of a listening device (or another energy-consuming device) hidden in roof space.

Thermal Imaging Cameras to Find Wildlife & Pests

Our thermal cameras are used by ecologists, researchers, pest controllers, and termite inspectors. Here's why:

• Pest Control & Animal Rescue. Thermal imaging cameras can find out where pets, birds, possums, rats or other animals are camping out in the roof or walls of a building. This saves time and prevents the unnecessary destruction of walls to locate trapped animals.
• Termite Detection. Infrared cameras can detect areas of potential termite activity in buildings as termite packing has a different density and moisture content to surrounding material.
• Wildlife Surveys. Thermal cameras are used to conduct wildlife surveys and other animal research. It's often easier, quicker, and kinder than other methods such as trapping.

The potential presence of termites detected with thermal imaging. We recommend at least a FLIR E8 for most termite inspectors.

Infrared Cameras in Healthcare & Veterinary Applications

We've sold thermal cameras to healthcare professionals and veterinarians all around Australia. We've also sold them to horse trainers - and animal welfare activists.

• Skin Temperature. IR cameras are a non-invasive tool to detect variations in skin temperature. Skin temperature variation can, in turn, be symptomatic of other underlying medical issues.
• Musculoskeletal Problems. Thermal imaging cameras can be used to diagnose a variety of disorders associated with the neck, back and limbs.
• Circulation Problems. Thermal scanners can help detect the presence of deep vein thromboses and other circulatory disorders.
• Infection. Thermal imagers can quickly locate potential areas of infection (indicated by an abnormal temperature profile).
• Animal Treatment. Thermal cameras can be used for diagnosis of tendon, hoof and saddle problems.

Image showing leg blood flow circulation issues. Customers using our infrared cameras for medical purposes have typically purchased a FLIR E6 thermal camera or higher.

Thermal image of the front legs of a horse. Animals can't tell you "where it hurts" so thermal imagers can be a particularly useful tool to support a diagnosis. Customers using our thermal cameras for veterinary purposes have typically purchased a FLIR E6, FLIR E8 or higher.

Fun & Creative Uses for Thermal Imagers

With the advent of ever lower-cost thermal cameras such as the FLIR One Pro - you no longer need to use them exclusively for the professional purposes outlined above.

• Show-off. And impress your geeky friends.
• Create. Use an infrared camera to create unique artworks.
• Search. Search for Bigfoot, The Yeti, Lithgow Panther or some other as yet unproven monster.
• Camping. Check out the nightlife when camping.
• Hot Air. See how much hot air people really generate.
• Selfies. Take an awesome thermal 'selfie' and get more Instagram followers.
• Barbecuing. Optimise the performance of your BBQ in an unnecessarily high-tech fashion.
• Pets. Take predator-style images of pets, or find out exactly where they have been sleeping when you arrive home (the warm patch on the couch lingers for ages, at least in the thermal spectrum).

Lucy Bleach's 'Radiant Heat' installation artwork in Hobart. For video, we recommend the FLIR E54 or higher, owing to their higher resolution and ability to record, output, and stream video. If your budget does not stretch that far, even the One Pro can now record thermal video using your iPhone or Android device.

Ready to order a thermal camera?

Click here to see our complete range of thermal cameras. Order online to get the best price and fastest service.

Still not sure what you need?

Read our FLIR camera review blog, check out our free online thermography training or book in some FLIR training.