Some infrared thermometers can vary the emissivity, and emissivity values for various materials can be found in published emissivity tables. Other instruments were fixed with an emissivity preset of 0.95. This emissivity value is for the surface temperature of most organic materials, painted or oxidized surfaces, and is compensated by applying a tape or flat black paint to the surface being measured. When the tape or varnish reaches the same temperature as the base material, measure the temperature of the surface of the tape or varnish, which is its true temperature. The ratio of the distance to the spot, the optical system of the infrared thermometer collects energy from the circular measuring spot and focuses it on the detector, and the optical resolution is defined as the ratio of the distance from the infrared thermometer to the object to the size of the spot to be measured (D :S). The larger the ratio, the better the resolution of the infrared thermometer and the smaller the measured spot size.

Laser aiming, only to aid in aiming at the measuring point. A recent improvement in infrared optics is the addition of a near-focus feature, which provides measurements on small target areas and is immune to background temperature effects. Field of view, make sure that the target is larger than the spot size of the infrared thermometer. The smaller the target, the closer it should be. When accuracy is critical, make sure the target is at least 2x the spot size.