LOFAR-HBA 5° × 5° Stokes-I residual images after DI and DD calibration with four different calibration scenarios on the RA 18h flanking field at frequency 113.9–127.1 MHz. The images are created with a pixel size of 0.2 arcmin using baselines 50–5000λ, combining 69 sub-bands and a single observation night L612832 (~11.6-h). Top: after DI calibration. Middle: calibrated by DDECAL (left) and SAGECAL (right) with the one-step method. Bottom: calibrated by DDECAL (left) and SAGECAL (right) with the two-step method. Different DD calibration scenarios also show different residuals. A source close to the centre is indicated by a dashed blue circle as reference. The residuals of the reference source look different in the four scenarios.