Initial mass functions used in this work. Black line is for Salpeter, red is for Kroupa, and green is for the Chabrier IMF. The plot shows the number of stars per logarithmic mass interval for each mass. Clearly, the Kroupa and Chabrier IMFs are similar and have significantly fewer low-mass stars than the Salpeter IMF. The dashed and dotted lines show the Kroupa IMF using somewhat higher characteristic masses. The effect of increasing the characteristic mass is that there are fewer low mass stars so the L/M ratio of the stellar population increases from about 900 L_⊙/M_⊙ to 1500 L_⊙/M_⊙.