摘要： Infrared thermography as a non-invasive contactless method of temperature distribution is ideal for various types of analyses. Thermal cameras have some protection against direct sprays of water and dust but no deposit on a camera is allowed. Educated camera operators often find themselves in situations where they have to conduct an analysis during which the equipment is exposed to unforeseen working conditions. One such occasion is dairy farming management. Analyzing dairy cows with a thermal camera exposes expensive equipment to faeces and urine. Camera protection is normally carried out by the usage of a thermal window, protective lens or special housing. One of the materials used in lens protection manufacturing is polyethylene used to make plastic bags. The paper elaborates on camera protection in order to support the usage of a plastic bag for camera protection when in unexpected circumstances. Two experiments were performed under controlled conditions and one in real conditions on a dairy farm with and without the usage of a plastic bag. The impact of the bag and its thickness on the results of thermographic analysis of a homogeneous radiation source at ambient temperature did not provide desired information due to thermal equilibrium. The setup analysis with a heat source that have the same temperature difference as a real cow in the farm has shown the influence of bag thickness as well as a different setup on the camera. The importance of a bag being well stretched over the camera lens in order to get homogeneous and minimal influence on the final measurement results was emphasized prior to the final shooting in the farm condition. In the dairy cow analysis, when the plastic bag was mounted over the camera, the temperature difference was observed. It was shown that the difference increases alongside with the increase of the observed object temperature. The plastic bag reduces the registered cow apparent temperature but similarly raises the ambient temperature.