To evaluate the fill factor enhancement, light at 532nm was injected into the multimode end of a photonic lantern, which was attached to a 9m length of multicore fibre. A single-mode at the output of the multicore fibre were then imaged onto the detector array with a magnification of M = 1.4. Under this magnification, the imaged core on the detector array is 2.52µm in diameter and it is reasonable to assume that all of the light falls inside the 6.0µm active area of the pixel. The total number of counts (col2) over a set time period was determined for this core-SPAD combination; this represents the maximum counts possible with a fill factor of 100%. The measurement was then performed for different magnifications ranging from M=1.4 to of M = 5.1 (col 1), including one at M=4.7, - the same magnification required to simultaneously couple the 121 MCF-cores to the 121 SPADs. Under this magnification, the core image on the SPAD is 8.15µm in diameter, and the overlap of the mode on the 6.0µm active area of the SPAD will be significantly reduced. Again, the number of counts obtained over a set time period was measured, and the resultant fill factor of the core-SPAD combination was then determined by dividing the number of counts measured in the first measurement by the number of counts measured in the second measurement. In order to calculate the effective fill factor of the 11 x 11 subset of the core-SPAD array, a computer simulation was performed.