The Tiffen 138mm Ultra Pol non-rotating linear polarising filter helps to significantly reduce reflections and glare by filtering polarised light due to reflection from a non-metallic surface. This results in a notable increase in saturation of skies and foliage, as well as sharper images when shooting in hazy conditions. A linear polariser differs from a circular polariser in that it does not support the use of the camera’s autofocus or automatic exposure functions; it is best suited for use with manual cameras, such as view cameras, which do not depend on internal mechanisms to determine focus or metering settings. There is a total filter factor of approximately 4, requiring an increase of 2 stops for normal exposure. This filter is constructed from Water White glass and manufactured using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass, grinding it flat to a tolerance of 1/10,000th of an inch, and then mounting it in precision metal rings. The non-rotating design of this filter is best suited for use with lens shades, adapters, or other rings for rotational control of the polarising substrate. - Compared to a standard polariser, the Ultra Pol design strives to increase the polarising effect for greater reduction of reflections and increased colour saturation. - Arranges and filters directionally polarised light perpendicularly to reflected light, allowing the absorption of much of the light. - Reduces haze in distant landscapes and provides more saturated and vivid colours. - Strongest effect when used at 90° to the sun. - Water White optical glass for excellent clarity. - Non-rotating design is best suited for use with lens shades or adapter rings for better control of the filter’s polarising effect.