Please note that Lee filters are handmade to order. Resin and glass filters and kits have a lead time of 8-10 weeks. All other Lee products have a 7 day lead time. Why use a Polariser? Polarising filters are used to manage light at wavelength scale, and if magnified could be a likened to a series of microscopic slats. In use, as the filter is rotated, it either transmits or blocks the waves of light that are vibrating in particular orientations. When light from the sun bounces off a flat non metallic surface, such as glass or water, it becomes polarised - i.e. all of the reflected light waves vibrate in the same plane. This reflected glare can be removed by the polarising filter. Rotation of the filter will be needed to find the optimum position of the Polariser. In photographic terms this can render water or glass transparent, and gives the impression of saturating colours in a scene, because much of the reflected glare from the subject is removed by the Polariser. On a clear sunny day, much of the light in the sky is also polarised, and the filter will give a very strong blue effect when used at 90 degrees from the sun - any white clouds will stand out impressively. When light from the sun bounces off a flat non metallic surface, such as glass or water, it becomes polarised with all of the reflected light waves vibrating in the same plane. This reflected glare can be removed by the polarising filter. There are two types of polariser, circular and linear. These names bear no relation to the physical shape of the filter itself but refer instead to the way the light waves are transmitted through the filter to achieve the polarising effect. Users with an autofocus SLR should use a circular polariser. Those with a manual focus camera, either 35mm or medium format, can use either a circular or linear polariser. The Lee Polariser Circular Filter for Seven5 (75mm Glass) S5PL (205650) has a unique clip-on design meaning it ca