Incompleteness fractions and fitted polynomials for the main-sequence reference samples (left panels) are shown vs. the J-band magnitude. Artificial stars were matched in JHK_s prior to the derivation of the displayed completeness fractions. For the excess source populations (right panels), incompleteness fractions and fits are shown vs. the L′-band magnitude for all artificial stars recovered in JHK_s and L′ simultaneously. The top panels show the completeness fractions in the Quintuplet cluster, while the bottom panels refer to the Arches observations. Thick bars in the top of the L-band panels represent the range of L′ magnitudes observed in the excess sources in each field.