Comparison of the sSFR against stellar mass for Hα- and IR-based SFR tracers. The CARS objects are shown as red points with error bars, while xCOLD GASS (xCG) are in small gray dots, KINGFISH are in blue and Herschel Reference Survey (HRS) in green. Specific SFR is calculated from Hα luminosity (left panel) derived after BPT morphology analysis and RAINBOW fitting using the SFR formula SFR_Hα = 5.3 × 10⁻⁴² × L_Hα (Calzetti et al. 2007). IR specific SFR (right panel) derived from the AGNFITTER modeling using the Murphy et al. (2011) SFR formula. The stellar mass is taken from the AGNFITTER modeling parameters. The background on the left plot is the density map of SDSS galaxies (Brinchmann et al. 2004). Linear models to the star-forming main sequence are shown as black solid lines from Renzini & Peng (2015) and Shimizu et al. (2015), respectively. The best-fit linear relation from the xCG sample is shown as the blue dashed line in both cases. Lower panel: residuals around the adopted star-forming main sequence where the colored bands (red, blue, and purple) emphasize three bins used further in Fig. 8.