IR Infrared Camera Auto vs Manual Range and Span Control Manual range and span control is a must in a thermal imaging system (IR Camera). Range/Span is the total scope of temperature a camera measures from high to low at any moment. For example we can set a camera to measure temperatures between 30F to 200F. The delta T within that range is 170F. The thermal imager is going to assign a color range within that 170F degree range.