Comparison of different age definitions to the age defined as the onset of star formation . Different colours indicate different timescales for the SFH: τ_SFH = 0.4 Gyr in red, τ_SFH = 0.6 Gyr in black, and τ_SFH = 1.0 Gyr in green. The different line styles correspond to three age definitions: solid line for half-mass ages ( ), dashed line for mass weighted ages ( ), and dot-dashed line for quarter-mass ages ( ).