When take measurement ,point thermometer toward the object to be measured and hold the yellow trigger.The object under test should be large than the spot size calculated by the field of view diagram. Distance & spot size : As the distance from the object increase,the spot size of measuring area becomes larger. Field of view : Make sure the target is larger than the units spot size .The small the target the closer measure distance .when accuracy is critical,make sure the target is at least twice as large as the spot size. Emissivity: Most organic materials and painted or oxidized surfaces have an emissivity of 0.95 (pre-set in the unit ),Inaccurate readings will result from measuring shiny or polished metal surfaces. To compensate, cover the surface to be measured with masking tape or flat black paint .Measure the tape or painted surface when the tape or painted reach the same temperature as the material underneath