Mass-to-light ratio and magnitude trends. Solid lines and left vertical axes represent the change in stellar M/L as a function of age (left), metallicity (middle), and IMF slope (right). When not varied, the age is fixed to 10 Gyr, the metallicity to solar, and the IMF to the Milky Way value. Similarly, dashed lines and right axes correspond to the expected absolute magnitude of the population. FASTAR predictions for the SDSS g band are shown in green while the expectation for the near-infrared JWST/NIRCam F090W filter are shown in red.