The Tiffen 6.6 x 6.6" 4 Point/4 mm Star Effect Glass Filter creates multiple points of light, or "stars", that radiate from a central light source. This can give the scene's lighting a more sparkling and glamorous appearance. This effect is produced by a series of fine lines etched into the flat optical surface of a clear filter. The size and brightness of the star lines produced depend primarily on the size, shape, and brightness of the light source. - You have additional control through the choice of a particular spacing between the lines on the filter; These spacings are measured in millimetres and range from 1 mm to 4 mm - A 1 mm spacing has twice as many lines as a 2 mm spacing; It will produce a brighter star for a given source - Lines in one direction produce a two-point star, just a streak across the centre of the light - Tiffen offers symmetrical 4, 6 and 8 point star effects as well as additional asymmetrical star patterns through their exclusive Hollywood FX series (North, Hyper, Vector and Hollywood star effects) - With an 8 point filter, the many star lines may tend to dominate the rest of the image, so use it with caution - In general, medium or larger apertures are sufficient to achieve a good star effect; Always test before critical situations Technical Specifications