In this paper, we used four distinct photometric data sets. First, we used Stetson (2000PASP..112..925S) ground-based B, V, R and I photometry. This photometric catalogue has been established from about 550 images taken at different telescopes, i.e. the Max Planck 2.2m, the Cerro Tololo Inter-American Observatory (CTIO) 4, 1.5 and 0.9m telescopes, and the Dutch 0.9m telescope in La Silla. In the present work, we have complemented the Stetson catalogue with images collected with the Wide Field Imager (WFI) of the Max Planck 2.2m telescope at La Silla (WFI@2.2m) through the U filter under the SUrvey of Multiple pOpulations (SUMO) campaign. >Secondly, to study stars in the halo of NGC 1851, we collected BVI images with WFI@2.2m of a field between ~10 and 35 arcmin to the south of the cluster centre. Photometry and astrometry for this data set have been obtained by using the program img2xym_WFI and the procedure described by Anderson et al. (2006A&A...454.1029A). Third and finally, to investigate the most crowded central regions, we use Hubble Space Telescope (HST) F606W and F814W photometry obtained with the Wide Field Channel of the Advanced Camera for Survey (WFC/ACS) and F275W photometry collected with the Ultraviolet and Visual Channel of the Wide Field Camera 3 (UVIS/WFC3). (2 data files).