BetterPhoto Q&A
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Ruslan Safin		What Do I Need For IR Shooting? How do I take infrared pictures? Do I need both IR film and IR filter or can I simply do without IR film, with a IR filter only? To love this question, log in above July 11, 2002

Jon Close		With b&w IR film you can use an IR filter (looks black, lets only IR pass through), a #25 red filter (common for regular b&w use), or no filter. IR film is sensitive to both visible and IR light. Normal film has little or no sensitivity to IR, so using an IR filter alone will give you blank negatives. IR film requires more careful handling. The felt at the mouth of the film cartridge does not block IR well, so the film must be removed from the plastic can and loaded in the camera in total darkness (or a light-tight changing bag). Many modern cameras (especially the non-pro EOS models) have a film advance system that uses an infrared emitter to count film sprocket holes. This emitter can fog the bottom edge of hight speed IR film. Pressure plates with a cutout for "QD" date-printing, and the window on the back for viewing the film cartridge pose other potential problems when using IR film. For more info, see photonotes.org/articles/ir-myths/ and photonotes.org/articles/eos-ir/ To love this comment, log in above July 11, 2002

John A. Lind		Jon has hit the general high points. One additional note . . . Most IR films do not have an antihalation layer. This is a special opaque layer removed during developing that prevents light from going completely through the film, reflecting off of the pressure plate and traveling back through the film. If your pressure plate has dimples or any marks or features other than a completely flat black surface, these features can show up in the image. Most pressure plates have a grid of dimples on them. Some cover the pressure plate with a piece of sturdy construction paper and others use a flat black tape such as electrical tape to cover it (the adhesives on most tapes can get a little messy when trying to remove it). I strongly recommend reading the data sheet(s) for the films you are considering. They have data about the film's spectral response and specific recommendations for film handling, filters, and processing. The spectral response of B&W IR films varies by specific film; how deeply into the IR region the film responds to IR and how much it responds to visible light. Same with IR color slide films. -- John To love this comment, log in above July 11, 2002

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