The Tiffen 4 x 5.65" Decamired Blue 6 Cooling glass filter - For those who want a foolproof method to obtain accurate colour temperature readings, the decamired system is the solution. Using this formula, you can easily and quickly transpose temperatures from one point to another.nnThis system is also useful when you want to bring creativity to colour photography.nnApplications include maintaining a constant colour temperature throughout the day and producing the effect of different times of day. Available in two series, reddish filters that warm the light and bluish filters that cool the light. Each series contains 4 densities: 1.5, 3, 6 and 12. Filters from the same series can be combined.nnDecamired filters are designed to handle unusual colour temperature variations more easily than the filters mentioned previously. Available in increments in the red and blue series, Decamired filters can be easily combined to create almost any required corrections. By measuring the colour temperature of the light source and comparing it to that for which the film was designed, we can predict the required filtration quite well.nnA filter that produces a colour temperature change of 100K at 3400K will produce a change of 1000K at 10,000K. This is because the filter relates to a visual colour scale. It will always produce the same visible difference. A colour change of 100K at the higher temperature would barely be noticed.nnCalculationsnnTo use this concept, subtract the mired value of the light source from that of the film. If the result is positive, you need a reddish filter; if negative, use a bluish filter. Coordinated mired filters are called decamireds. The mired value divided by ten gives decamireds. The 60 mired shifts mentioned above would be produced by an R6 filter, where the higher values were those of the lighting.nnSets of these filters are typically available in values of 1.5, 3, 6 and 12 decamireds in B (bluish) and R (reddish) colours. These numbers are additive; that is, a pair of R3 produces an R6. An R6 plus a B6 cancel each other out to produce a neutral grey.nnThe decamired system has an advantage over the Kelvin system in that the Kelvin scale is not linearnnDecamired readings provide more accurate/controllable readings than KelvinnnThe difference between the Mired value of the film and the Mired value of the light is the Mired value of the correction filter that correctly matches the light to the filmnnA simple formulan-Mired Value = 1,000,000 ÷ Kelvin Valuen-Kelvin Value = 1,000,000 ÷ Mired Valuen-For 5600K daylight colour film, the Mired value is 1,000,000 divided by 5600 = 178.6n-For 3000K artificial light, the Mired value is 1,000,000 divided by 3000 = 333.3n-178.6 Mired - 333.3 Mired = -54.7 Mired, or -5 Decamiredn-A positive value indicates a reddish KR filter, a negative value indicates a bluish KB filtern-Thus, the filter required to match 3000K halogen light (the slightly low value results from mains voltage being below its rated voltage) to 5600K daylight colour film is a blue conversion filternnColorCore TechnologynnTiffen filters are manufactured using ColorCore technology, a closely guarded proprietary process that involves permanently laminating the filter material between two pieces of optical glass that are polished to tolerances of one ten-thousandth of an inch, then mounted in precision metal ringsn-The ColorCore process allows Tiffen to control the colour and density of their filters, as well as special effects filter characteristics with much greater precision than typical mass-dyed filters, which typically exhibit colour and density variationsnnSuperior QualitynnHollywood's major film studios rely on Tiffen filters for their multi-million dollar productionsn-Superior quality and design make Tiffen the undisputed choice of filmmakers, professional photographers and even NASAn-Tiffen has also received an Emmy from the Academy of Television Arts and Sciences for engineering excellence