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Thermal Camera Buyers Guide

People ask us all the time, "Which thermal camera is right for me?" We love answering this question. The answer of course depends on how you want to use the camera. While there are usually several imagers to consider for any given application, there are also some imagers that will be better than others for that application. Our answers vary based on some combination of the following considerations.

How well a thermal camera measures a temperature or creates an image is primarily an effect of its infrared detector. This is the piece of hardware that detects infrared energy coming through the lens. Simplifying a bit, we are concerned with two aspects of the detector: sensitivity and resolution.
FLIR T440 Thermal Camera

Sensitivity


Sensitivity refers to how well the detector can detect infrared energy- related to how sensitive it is to temperature. One thermal imager may be sensitive to 0.10° C, while another may be sensitive to 0.05° C temperature changes. The more sensitive detector will see smaller temperature variations and use this information to create a sharper image.

Resolution

An image is created by taking multiple measurements, converting these to an electronic signal, then displaying the results. The resolution of a camera relates to how many measurements the detector can make. The infrared thermometer (or "spot temp gun") takes a measurement from one point. It's resolution is 1x1, or 1 pixel. A thermal camera with a resolution of 120x120 takes 14,400 measurements simultaneously. It can use the different temperatures in those 14,400 pixels to create a meaningful image for the user.

But what about different resolutions? When close to a target, each pixel detects information from a smaller area, giving better detail. As you back away from the same target, each pixel is detecting information from a larger area of the target. You can now see more of the target in the image, yet it has become harder to see small details. This is where a higher resolution imager can help. A camera with a higher resolution can scan a larger area or provide more detail than a lower resolution camera.

TemperatureFluke Ti100

How high a temperature will you need to view or measure? Or how small a temperature variation might you need to visualize? These are important considerations, as some thermal cameras are designed for certain operating conditions. Take the FLIR E-Series bx for instance. This is a fantastic line of imagers designed for conditions often found in the built environment. It's capable of sensing some of the smallest thermal variations, and has a working temperature range of -4° to 248° F. It will make accurate measurements, produce sharp images, and generally make your job easier if these are the conditions you are working under. If you work at a manufacturing facility, however, and need to measure or image an object that's 500° F, you should consider a different line of imagers- in this case the FLIR E-Series, capable of temperatures up to 662° F.

Other Features

  • Image Presentation - All current thermal cameras offered by major manufacturers have the ability to save infrared images, usually at least 1000 depending how they are saved. These are saved to onboard memory in the form of an SD card. The images can be downloaded to a computer via a USB cable or SD card reader. Some thermal cameras can also record thermal video, a great option for viewing thermal patterns over time. If equipped with a digital camera (see below), some thermal imagers can present digital and infrared images overtop of one another ("picture-in-picture"), or blended together ("fusion").
  • Digital Camera - Some cameras have a digital camera incorporated, allowing the user to record visible light and infrared images at the same time. This aids clients or other contractors in locating the problem area, since the visible light photo makes it easier to understand where the thermal image was taken. As a side benefit, imagers with digital cameras also often have strong LED flashlights, great for lighting the digital image as well as finding your way through a dark attic.
  • Focus - Thermal images need to be clear if they are to be useful. Different thermal cameras deal with this in different ways. Lower cost cameras have a fixed lens–there is no option to change the focus ("focus free"). These cameras are always in focus when the camera is about 4' or more form the target. This makes quick work of scanning a large area, but gives challenges when imaging close to a target. Manual focus cameras have a focus ring so that the user can find the optimal focus at any distance to the target. This gives more flexibility in capturing the optimal image. Autofocus provides the best of both options. An autofocus thermal camera will instantly focus on a target with the push of a button–perfect for one handed operation. Yet autofocus cameras also provide manual focus so that the user has complete control of the image. Some newer cameras such as the FLIR T640 even provide full-time autofocus, constantly and automatically updating focus.
  • Annotation - Depending on the task, it can be cumbersome to carry around a clipboard, and time-consuming to match up written notes with images later. Many cameras can help you record your notes right alongside the image. This can be through voice, text, or even sketching right on the touchscreen.
  • Compatible Tools - One helpful feature to many users is being able to wirelessly link together a thermal imager and another tool, such as a moisture meter or clamp meter. The imager can add the data from the compatible tool directly to the image data for better understanding and reporting of problems.
  • Connectivity - In recent years the ability to connect a camera to various computer equipment has come a long way. You can now wirelessly connect some cameras to your iPhone, iPad, or Android device. For an unbeatable presentation, some thermal cameras can stream video to a computer connected to a large screen monitor or TV.
  • Alarms - When surface conditions are near the dew point, or insulation may be missing in a stud cavity, certain imagers are equipped to sound an alarm.
  • Etc. - Other features to consider are durability, laser pointer, digital zoom, the option to use wide angle and telephoto lenses, extra batteries, etc.
What do you need to see? Or measure? Give us a call–we would be happy to make camera recommendations for any application. Or start comparing right away in our gallery of Thermal Cameras.