The Tiffen 4 x 4" Full Spectrum IRND 2.1 Filter is a combination of both an infrared control filter and a 2.1 neutral density filter. An IRND is ideal for HD cameras, which have greater low-light sensitivity and, subsequently, an increased susceptibility to IR contamination. When using a standard neutral density filter to counter the increased light sensitivity afforded by the HD sensor, the effects of infrared pollution become more apparent. This filter combines an ND filter with a comparable IR control filter to eliminate the spill of infrared light reaching the sensor while still maintaining the extra exposure benefits of a neutral density filter.
This filter is constructed from Water White glass and is made using ColorCore technology, a process that involves laminating the filter substrate between two pieces of optical glass and grinding flat to a tolerance of 1/10,000th of an inch. This filter measures 4 x 4" / 101.6 x 101.6mm.