TIFFEN IRND 0.3, 0.6, 0.9, 1.2,1.5, 1.8, Pola, Clear

SAY GOODBYE TO IR POLLUTION

http://www.tiffen.com/irnd_intro_poster.html

Until recently, the use of film for Motion Pictures allowed DOP’s the greatest latitude. When lighting characteristics and exposure needs varied, the appropriate film stock could be selected to provide the optimum results. Filters could be used to fine tune the optimum results. Color timing in developing added further to the filmmaker’s options.
Now with the advent of Digital Motion Picture Cameras and a digital imaging device taking the place of film, DOPs no longer have the option of selecting the optimum film for their application. They must now deal with a one size fits all imaging device that is designed to replace all the various film types; what you see is what you get. This means that the use of filters regardless of the capture format rate is even more critical in achieving the desired results.
Because the imaging device is designed to be sensitive in low light conditions it is easily over exposed in bright situations. The Neutral Density filter is used to help control this situation as well as to gain more control over depth of field. Up to now ND filters made with dyes did this job, but passed small amounts of red and near infra-red light to create their transitional slope between attenuating visual and passing infra-red.
In addition to the visual spectrum, digital imaging devices are sensitive to Infra-Red. This Infra-Red can have an effect on the quality and the color of the image. Digital imaging devices require higher grade neutral density filters but are sensitive to infrared (IR). This IR pollution has an adverse effect on the quality and the color rendition of the images – stealing contrast and color, resulting in unwanted color shifts. Greens become a reddish muddy brown and blacks have a magenta hue. To combat this problem, some camera manufacturers use an IR blocking filter in front of the imaging device – most notably, the Sony F23, F35 and the Panavision Genesis. However, when you combine a neutral density filter with cameras containing a built in IR blocking filter, the result is a spike in the near infra red.