Number densities in two rest-frame magnitude intervals estimated for our Hawk-I data set in a stepwise form with a standard Y − UV conversion of the observed number counts as discussed in the text (black filled squares), or with a χ² method considering also photometric and model uncertainties (black empty circles). Other points are from Bouwens et al. (2010a) (NICMOS, red empty squares), Ouchi et al. (2009a) (SUBARU, blue empty squares and upper limits) and Oesch et al. (2010) (WFC3-UDF, magenta empty circles). For comparison we show the recent determinations of the LF at z ~ 6 by Bouwens et al. (2007) (B07, green dot-dashed line) and McLure et al. (2009) (M09, blue dashed line). The black solid line is the best-fit LF obtained by combining the stepwise points shown in the figure with new determinations of the binned densities from WFC3-UDF and WFC3-ERS data (Grazian et al. in preparation).