Left panel: m_F814W vs. m_F475W − m_F814W CMD for MS stars. Blue dashed lines and red dotted lines are the MSRLs of the bMS and the rMS blue and red-shifted by  ±three times σ_bMS and σ_rMS. The red dashed-dotted line is displaced to the red from the fiducial of equal-mass rMS-rMS binaries by  + 3 times σ_rMS. These lines are the boundaries of the shaded areas in the right panel that define the four regions used to calculate the LFs of the three MSs and the binary fraction (see text for details).