4. Shooting with Infrared FilmWhen using black-and-white infrared film make a slight adjustmentin focus with the red infrared index.For example, focus the subject first, then if the lens is focused at5m on the distance scale, turn the manual focusing ring to align the5m mark with the red dot and release the shutter.· When using infrared film, use a deep red filter as specified by themanufacturer.· The infrared index mark position has been computed for infraredfilm usage with peak sensitivity at 800nm.· Read the manufacturer's instructions when using color infraredfilm.AccessoriesSpeedlites 420EZ/300EZThese are high-performance, electronic flash units featuring A(Advanced)-TTL automatic flash output control, which respond to a widerange of illumination from dark surroundings to bright (fill-in flash). Theyhave a built-in auto internal zoom mechanism in the flash head whichautomatically adjusts the flash coverage angle to use flash energy moreeffectively. In addition, the rapid-fire flash system enables you to take aflash picture in no less than 1 second with the 300EZ or 1.5 seconds withthe 420EZ. The guide numbers are 35 (ISO 100.m) or 116 (ISO 100-ft.)with the 420EZ, and 28 (ISO 100.m) or 93 (ISO 100.ft.) with the 300EZ.· The above figures show the guide numbers when the flash head is setat the 50mm position at full charge.