Tiffen 6785 67mm 85 Filter

Colour conversion filter decreases color temperature and provides a warming effect. Converts 5500 to 3400K for using tungsten-balanced film in daylight conditions. Filter factor of 1.6 requires a 0.6-stop increase in exposure. This filter is made using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass, grinding flat to a tolerance of 1/10,000th of an inch, and then mounting to precision metal rings.