(57) Atungsten halogen incandescent lamp having a filament support structure made of molybdenum and a filament shield, also of molybdenum, to provide an assymetric passing beam in an automobile headlight. When operating with the halogen bromine small changes in the design or positioning of the shield can be critical and can cause darkening. This can be prevented by applying a small amount of the metal platinum to the back of the shield by plating, by means of a paste or in any convenient manner. In a specific example 13 microgrammes of platinum were used in a 55-60W H4 automobile headlight having a fill of bromine and krypton.