A mired shift refers to the adjustment of a light sources colour using filters, often Wratten filters, to match the colour balance of a film or sensor. By knowing the mired values of the light sources, photographers can calculate the precise filter needed to correct colour temperature differences. For example, using daylight-balanced film (5500K) under tungsten lighting (around 3400K) would require a filter with a mired shift of –112 to achieve accurate colour reproduction.
Mired shifts are essential in both film and digital photography when working with mixed or non-standard lighting. They allow photographers to maintain consistent colour across a scene, ensuring natural tones and accurate skin colours without relying solely on post-processing corrections.