The Tiffen 77mm Digital HT 4 Point/2mm Star Effect Filter is a cross screen filter providing 4 reflected light points stemming from specular highlights within the image frame. When the filter is rotated in front of the lens, the points shift in direction but always reflect symmetrically north-south, east-west. This effect is caused by thinly etched lines on one of the planes of the filter. These etched lines are spaced 2mm apart, producing visual depth and separation between light points in the resulting image. Star effect filters are most effective when not used in combination with other filters.
The Digital HT coating is a high transmission multi-coating that surpasses military specifications for hardness and durability. This optical purity combined with high scratch-resistance results in an easy-to-clean filter with superb imaging quality. They also feature low-profile titanium filter rings for increased strength and vignetting reduction.
Tiffen filters are 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, then mounting to precision metal rings.