Infrared radiation belongs to the same
family of waves that includes other familiar forms such as visible
light, X-rays and radar. On special film, you can take pictures using
what is called "near infrared"; this is the part of the spectrum that
lies between what our eyes see as deep-red visible light and what we
feel on our skin as radiant heat.
Infrared black-and-white film is
sensitive both to visible light and to infrared, and this broad
sensitivity provides extra creative opportunities. By using filters,
you can choose exactly what part of the spectrum you record on film.
Without filtration, the landscape looks quite normal, though the images
are fairly grainy. However, if you fit red or orange filters, you'll
find that all traces of haze (but not mist or fog) disappear from the
landscape, so that even far-distant subjects can be seen clearly.
The filters that have the most radical
effect, though, look black to the eye. These are the Wratten series 87,
87C or 88A. Photographed with any one of these filters, foliage appears
white whereas blue sky appears black. These filters stop visible light,
but not infrared, so don't hold them up to the sun - you'll see no
light but your eyes will be damaged, perhaps permanently.
Focusing and exposure require extra care
with infrared film. Focus the camera lens normally without a filter in
place, note the subject distance, and then move the focusing ring until
the distance setting is alongside the orange lR focusing index on your
lens. To set exposure, meter without the filter in place, using a
setting of ISO 50 with filters you can see through, or ISO 25 for
You'll also need to take special
precautions to guard against fogging. Load the film into the camera in
total darkness, and store unused cassettes in a freezer before use,
giving them time to thaw before loading.