Shots were made with an old Practica PLC3 or Kiev 88 (6 x 6) camera with Hoya R72 filter (Wratten 89B). I measured light with handheld exposure meter and always made two shots. First as if the film would have 6 ASA and the second as 12 ASA. Both prints are usable, but the one with smaller speed (6 ASA) has more pronounced IR effect.