At the time of rapid development of LED technology, certain problems are associated with the measurement of the luminance distribution of multi-source LED luminaires. The construction features of luminaires which form luminous intensity distribution by means of lens systems causes problems in achieving high values of luminous intensity, at a level of 100.000 cd in particular directions, is associated with high values of the luminance, often getting levels higher than 10 million cd/ m2. Despite the rapid development of measurement techniques and the widespread use of imaging luminance measuring devices (ILMD), the appropriate luminance measurement of multi-source luminaires very often leads to errors. Technical problems substantially affecting the accuracy of the luminance measurement of small objects are presented in this paper. The problems are universal. Taking into account the rapid digitization of measurement methods in lighting technology, paying special attention to increasing measurement errors acquires a particukar importance.