Similar to Fig. 8, except that both panels are in the R band. The upper panel is for EFOSC2@NTT with a degraded seeing of 1.2 arcsec FWHM, while the lower panel is for optimistic sky conditions of 0.7 arcsec but on a 1 m class telescope equipped with a camera equivalent to EFOSC2. These histograms show the evolving role of the a priori information in improving the astrometry depending on sky conditions and the equipment used. The benefits of using the Bayesian approach is noticeable at the faintest bins.