Special filter with ultra-flat rotary mount (45 mm) For wide-angle & wide-angle zoom lenses especially for fast AF lenses with integrated motor drive or front lens focus No vignetting (dark shading of picture corners) New super-quality optical glass (only 1 mm thick) From 17 mm focal length (in case of miniature photograph) Very low weight Multi-layer coating (C14) seven layers of coating are vapour-deposited on each side Quality standard (glass) Pro Class Colour of mount black Impact of picture (like Polarizing Filter circular) Puts contrast & depth in the picture the sky gets blue the clouds get white & the colours become clearer According to the position of the filter non-metallic reflections (water plastic glass etc) are removed The best effect is achieved with a shooting angle of 30-40° to the reflective surface