6 pages, 3 figures. To be published on Optics Letter.-- Final full-text version of the paper available at: http://www.opticsinfobase.org/abstract.cfm?URI=ol-30-17-2317We present experimental and theoretical work showing that a flat metallic slab can collimate and focus light impinging on the slab from a punctual source. The effect is optimised when the radiation is around the bulk, not at the surface, plasma frequency. And the smaller the imaginary part of the permittivity is, the better the collimation. Experiments for Ag in the visible as well as calculations are presented. We also discuss the interesting case of the Aluminium whose imaginary part of the permittivity is very small at the plasma frequency in UV radiation. Generalization to other materials and radiations are also discussed.This work has been supported by the EU-FP6, Molecular Imaging Project and by the Spanish DGICyT.Peer reviewed