A Blacksun Filter is an advanced optical filtering suite employed by Tau military units that comprises of several unique sensors and lenses, similar in function to the Photo Visor of the Imperium. A Blacksun Filter boosts ambient light and makes certain frequencies of light visible to the wearer, magnifying a warrior’s low-light vision. The filter is also designed to temporary block out extremely bright lights that could otherwise blind the user in battle. This is especially useful for Fire Warriors to avoid being blinded by their own Photon Grenades. With Blacksun Filters, target calibration systems sensors can also lock onto enemies with full efficiency and range even during night-fighting operations. This has proved to be a major advantage for Tau forces in many campaigns, where surpris