FG filters can be used to increase or decrease the colour temperature of radiation sources based on their special spectral curves.

Fine adjustment may be achieved through suitable selection of the filter thickness. Examples of areas of application are in photo and illumination technology and microscopy. By using conversion filters one can switch over and back from artificial light, such as incandescent lighting with a relatively low colour temperature to an impression of daylight (colour temperature ca. 6500k). The examples cited only present a small picture of the many possible applications for optical glass filters.