Colour composite image of NGC 2419 from J, H, and K_s images. On the left side the full 4 × 4 arcmin field of LUCI is shown, fitting well the whole cluster. To the right a zoom into the cluster core, showing the richness and density. Taken during the commissioning of ARGOS, we can use this example to measure the adaptive optics performance over the field. NGC 2419 with its large number of stars provides a good map for the uniformity of the FWHM.