Point source fraction as a function of intrinsic resolution (it decreases to the right). The intrinsic resolution is the resolution of the interferometer divided by the inner radius of the source, i.e. 5 mas/(2 r_in). In the two bright sources, MIDI’s resolution almost reaches r_in, while in the weak sources our resolution corresponds to radii 4−12 times as large as r_in. Type 1 sources are denoted as blue stars, type 2 sources as red diamonds, the source names are given next to the symbols. As before, objects which we model with case 1 are marked with a green square.