Reflected infrared photography:
Other considerations

It should be noted that many materials transmit infrared freely, examples being some of the plastics used in the manufacture of sheet film dark slides, developing tanks, cameras and camera bellows (Figure 47 shows an example). Care must also be exercised when using "changing bags' with the true infrared films - Kodak HIE and the Maco 820c - as the black cloth material may transmit infrared.). It is imperative, therefore, that all equipment to be used for infrared photography is tested prior to use in order to avoid fogging the film. Incidentally the ability of infrared to pass through some dark materials has led to sensational reports in the press about the "See through clothes ...x-ray" images obtainable from digital cameras (Figure 48) - no doubt providing a healthy boost to sales!

Figure 47 (left). Many materials transmit infrared freely despite their appearance in visible light this includes some plastics used for the manufacture of darkslides and camera bellows.

Figure 48 (above). The black material that this bag is made of is quite black in normal light (left) but almost transparent to infrared (right) - notice how clearly the writing can be read through the bag. This has been described, quite erroneously, as an 'x-ray effect.' Images © MaxMax.

Not all cameras are suited for infrared use - even if their construction is infrared opaque. Some modern cameras, for example, use infrared devices for film loading and frame counting. These cameras will fog infrared film or at the very least the rebates of the film. The Canon EOS Elan/100, A2 E/5 and Hasselblad Xpan are all reported as causing this effect. Other cameras have dimpled pressure plates to reduce frictional drag which then cause problems with the Kodak HIE film and halation (reflection from the pressure plates causing halos around bright light sources in the image). The Pentax LX and K1000 are both reportied as problematic in this area. Minolta cameras like the 9xi and 700si, which had a pressure plate with a circular hole built to accommodate a data back are also reported as causing the same problem. Infrared LED databacks, common on compact 35mm cameras, fog infrared film and so must be turned off. Others have reported problems with infrared leakage around takeup spools and re-wind handles (the Horizon 202, for example), or through plastic film identification windows. The only reliable approach is test everything first.

Some workers have advocated the use of the twin lens reflex camera for infrared work as this enables the photographer to maintain visual framing while the imaging lens is fitted with the visually opaque infrared transmission filter. Whilst certainly convenient this method still requires a focus adjustment and may further be subject to parallax error between the two lenses.

< Processing infrared Ektachrome

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