I have been organizing my “old shoe box” and found a set of my favorite slides from a trip to Iceland in 2002. In the pre-digital era, one of my favorite films was Kodak Ektachrome Infrared “EIR”. This film had a IR-sensitive layer that with the help of specific color filter, could turn the near-infrared radiation of an scene into a colorful image.
Good old EIR required special treatment. All EIR color layers are sensitive to the blue spectrum and therefore blue needs to be filtered to avoid a murky image. A yellow #12 filter is perfect for that job as it absorbs most blue radiation, letting the higher part of the light spectrum, towards the red and infrared, pass-through.
Nowadays we have the immediate feedback of the LCD screen of the digital camera but at the time, imagination was your best preview. Learning to visualize an scene in infrared was required to make the most of this -rather expensive- film.
One thing I certainly miss in these digital days was the emotion to go to the lab to pick up your developed slides, place them on the light box and discover the how the infrared light, invisible for the eye, looked in your final image. My heart used to tick faster every time.