Abstract: A metal halide discharge lamp with a coaxial discharge vessel (2) and outer ulb (9) contains a fill of metals with a tendency to diffusion. Their specific content is less than 6 .mu.mols/cm.sup.3. The current supply leads (4, 5) are surrounded, over a large portion of their length, by a sheath (14) that is UV-shielded.

Abstract: To permit rapid adjustment of a holder structure (4) within which a singlnded pinch-sealed light source, for example a halogen incandescent lamp (1, 2) is retained, to a positioning or locating element having an optical reference surface (17a) to accurately align the light emitting element (2) of the light source with respect to an optical system, for example a reflector, a tubular adjustment sleeve (10) is provided into which the holder structure is fitted. The tubular adjustment sleeve has an essentially cylindrical portion (11) and a slightly conically converging portion (12) or an inwardly extending rim or ring (12') to permit rotational, axial and tilting adjustment of the holder structure to which the light source (1) is coupled with respect thereto. The tubular sleeve is formed with a laterally projecting flange (14, 14a) formed with a plane, burr-free engagement surface (14b) which fits against an auxiliary plane, flat reference surface (18b) on the positioning or locating element (15).