Infrared film is being used today in motion picture cameras more often and this is information pertaining to that.

There are two different Kodak infrared films usually used when an infrared effect is desired. One is 2481, a black and white stock and another is 2443, a color stock. The black and white film comes in 150 foot rolls and has Bell & Howell perforations which is correct for motion picture cameras. This black and white film will give the following:

1.  A blue sky will appear dark.
2.  Any green foliage will appear to be white and will appear to have snow on it.
3. Skin tones will appear to be darker than normal.
4. Everything will appear to be contrasty and this will vary according to the filter used. 
5. The following filters can be used: #25, #87, #88A, &89B

With the #25 filter, you will be able to see through the reflex viewing system.

With the #87, #88A and #89B, you will not be able to see through the reflex viewing system. For many cameras, Clairmont Camera can supply special special black & white  video assists that will see through these filters and the operator can use a monitor to operate the camera.

When using infrared film, the distance scales on the lens will not be perfectly accurate. If you are using a lens opening of F8 or smaller, there should be enough depth of focus to take care of the problem. It is possible to adjust the lens or put a new witness mark on the lens to compensate for the infrared. This correction is a change in back focus of .0025 percent of the focal length of the lens. A 25mm lens would have the back focus changed by .0625mm. It is better to just put a new witness mark on the lens using a collimator set closer to the lens by .0025 percent of the lens focal length. Most still camera lenses have a red mark to be used as a witness mark when focusing. Because of this focus shift, a zoom lens cannot be used.

Kodak #2443 film (which is color film) requires a #12 yellow filter to be used. Harrison and Harrison calls this filter Y6. With this filter, the color in the scene will be altered in bizarre colors depending on how objects radiate infrared light. The color film comes in 150 foot rolls and has Kodak standard perforations. While this is not the correct perforations for movie cameras, it will work. Assume the ASA of the color film to be ASA200. If possible, shoot tests first as this ASA will vary depending upon how much radiation there is. This film is good with infrared light up to 900NM.

With the black & white 2481 using the #25 filter, assume the ASA in daylight to be ASA50 and with tungsten light ASA125. With the #87 filter assume ASA in daylight to be ASA25 and in tungsten light ASA64. When filming in daylight with the black & white #2481 and the #87 filter, the stop is usually between F8 and F11. The film is also good with infrared light up to 900NM.

Load the film in a dark room that has no painted windows as infrared light may pass through the paint. Test changing bags by putting a piece of the black & white film into the bag while in a dark room. Take the bag into light, unload the bag in darkroom and develop film 11 minutes in Kodak D-76 developer. Use normal stop bath. Examine film for exposure (there should be none). Develop film in 35mm developing tanks and use no safe light.

There can be problems with certain cameras using infrared film. The black & white infrared film is very translucent and the color infrared film, though less translucent, is still a problem. Because of this, the camera must have a black pressure plate or the light will pass through the film and reflect back causing an exposure problem and making the photographic impression of the shiny bars on the pressure plate. Arriflex 2C's and Mitchell cameras do not have this problem since they do not have chrome pressure plates. All the modern cameras have chrome pressure plates. Clairmont Camera can provide black pressure plates for the Arri 435, Arri 3's, Moviecam and Eyemo cameras and we're working to get black pressure plates for all other cameras. 

The Arri 435 and 535 cameras have an infrared LED. light inside the camera that counts the perforations on the film. The film perforations counter and circuit board must be removed on the 435 with only the film perforation counter housing being reinstalled. The 535 has the perforation counter in the dummy module or the time code module and this module can be removed on the 435 and 535 with the perforation counter disabled, the cameras will perform perfectly except it will not turn off if the camera runs out of film.

The problem with the light passing through the film and reflecting off of the pressure plate and effecting the film can be a problem with normal Kodak black & white film under certain conditions such as overexposure of an object or sky scene.

Ilford makes a black & white film called SFX200 that is partially sensitive to infrared radiation up to 740NM and can be used with the #25 filter. It's ASA is 200 under daylight and 100 under tungsten light. The #25 filter has a light loss of 1 1/2 stops. If an 89B filter is used, the effect is greater and the light loss with the 89B filter is 4 stops.

This Ilford SFX200 film is not as sensitive to infrared radiation as the Kodak film but will render the sky very dark and will lighten foliage. This film is not translucent so the pressure plate being shiny is not a problem and the infrared LED. in Arriflex 435 and 535 cameras is not a problem.

Store the infrared film under the same conditions you would store your normal film.