Whether you are learning to use a thermal image camera or you are a professional thermographic, you have heard of the phrase “focus first.” The rationale for this phrase is very simple – of the settings that can be adjusted on your thermal camera, the focus is the most important when it comes to improving the accuracy of your thermal imaging camera.
Focus is crucial when it comes to both temperature accuracy and image quality. A blurry thermal image will disguise a critical anomaly in temperature in a piece of equipment. When an image is out of focus, it can produce a temperature measurement that is off as much as twenty degrees or even more. This temperature difference could lead to an incorrect conclusion.
Shooting out of focus could lead to bad data
The top reason why we use a thermal imaging camera is to get quality results. By quality results, we mean accurate data. However, when you should your images out of focus, it means that you will get inaccurate data. This means that you will be unable to use your findings.
Emissivity vs. reflected light
Focusing on a target with your thermal camera comes with a lot of challenges. In fact, the challenges are more than just focusing a visible light camera. With visual image cameras, you can take advantage of the light that tends to produce contrast between objects.
On the other hand, in night vision equipment, we need to deal with the energy that surfaces emit. It is unusual to have surfaces that have sharp temperature differences close to each other. This means that as heat energy moves through liquids, solids and gasses, crisp lines between things disappear and this makes it a big challenge to gain focus. There are some ways to improve your focus when using a thermal imaging camera.
The first thing you need to do is to turn your thermal imaging camera to a grey scale. Your eye can focus more easily in a grey scale than in other colour palettes. You should also look for a sharp edge in your field of view. You need to hold your camera still when using it. If you have a fluke camera then you should use the IR fusion in a picture-in-picture mode.
Choose the right type of focus
One of the most important things to consider when choosing the type of thermal imager focus system is making sure it matches the applications. When choosing a thermal imaging camera, you can choose from manual focus, fixed focus, and autofocus.
Fixed focus offers point-and-shoot technology to focus on targets at specific distances. These cameras have low resolution and are used to quickly scan an area to see the obvious cold and hot spots.
On the other hand, manual focus is used by experienced thermographers and cameras that use manual focus are high resolution. They can be used to focus close to the target and capture sharper images further away. They require more time to achieve precise focus.
Autofocus is a type of thermal image camera focus system that encompasses a variety of auto-focus technologies. It can be used by both novice and experienced thermographers.