The Series 9 Decamired Blue 1.5 Cooling Filter from Tiffen is for those who want a sure-fire way of getting accurate color temperature readings. Using this formula, you can transpose temperatures from one point to another easily and quickly. This system is also useful when you wish to bring a certain amount of creativity to color photography.
Decamired filters are used to maintain consistent color temperature during the day's shooting. Decamired filters are available in two series - reddish filters that warm the light and bluish filters that cool the light with each series available in four densities: 1.5, 3, 6, and 12. When filters from the same series are used, they can be combined.
Decamired filters can be readily combined to create almost any required color correction. In measuring the color temperature of the light source, and comparing it to that for which the film was designed, required filtration can be easily calculated.
A filter that produces a color temperature change of 100K at 3400K will produce a change of 1000K at 10,000K. This is because the filter relates to a visual scale of color. It will always produce the same visible difference. A color change of 100K at the higher temperature would hardly be noticed.
To use this concept, subtract the mired value of the light source from that of the film. If the answer is positive, you need a reddish filter; if negative, use a bluish filter. Mired-coordinated filters are termed as decamireds. Mired value divided by ten yields decamireds. The 60 mired shifts, above, would be produced by an R6 filter, where the higher values were that of the lighting.
Sets of such filters generally come in values of 1.5, 3, 6, and 12 decamireds in both B (bluish) and R (reddish) colors. These numbers are additive; that is, a pair of R3's produces an R6. An R6 plus a B6 cancel each other out to produce a neutral gray.
- The decamired system has an advantage over the Kelvin system in that the Kelvin scale is not linear
- Decamired readings provide more accurate/controllable readings than Kelvin
- The 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 balances the light to the film
A Simple Formula
- Mired value = 1000000 : Kelvin value
- Kelvin value = 1000000 : Mired value
- For 5600K daylight color film, the Mired value is 1,000,000 divided by 5600 = 178.6
- For 3000K artificial light, the Mired value is 1000000 divided by 3000 = 333.3
- 78.6 minus 333.33 equals -154.7 or -15 Decamired
- A positive value indicates a reddish KR filter, a negative value indicates a bluish KB filter
- Thus, the filter required to adapt the 3000K halogen light (the slightly low value results from the mains voltage being lower than its nominal voltage) to a 5600K daylight color film is a blue Conversion Filter
- Tiffen filters are manufactured using ColorCore technology, a closely guarded proprietary process that entails permanently laminating the filter material in between two pieces of optical glass that are ground flat to tolerances of a ten-thousandth of an inch, then mounting them in precision metal rings
- The ColorCore process allows Tiffen to control the color and density of their filters, and the characteristics of special effects filters with much greater accuracy than typical dyed-in-the-mass filters, which usually exhibit color and density variations
- Top Hollywood motion picture studios rely on Tiffen filters for their multimillion-dollar productions
- Superior quality and design make Tiffen the overwhelming choice of moviemakers, professional photographers and even NASA
- Tiffen has also been awarded an Emmy, from the Academy of Television Arts and Sciences, for its engineering excellence