Murder in Black and White
Generally I am off murder shows, even old time radio ones although there are exceptions. I was listening to this one: https://www.oldtimeradiodownloads.com/crime/casey-crime-photographer/murder-in-black-and-white-1948-03-18 One thing that stood out was the phrase: black light. Since the 1960s this probably refers more to ultraviolet light for posters but in this case the reference was to infrared, IR. In the olden days Kodak and others sold special infrared film. I remember one time I tried it and the leaves on the trees came out white rather than dark as was usually the case with black and white. Manual focus cameras also often had a red dot on the focus dial. To take an IR photo you'd focus the camera and then move the focus ring to the red dot since IR focuses in a different plane than visible light. But you could also buy flash bulbs for infrared. In the Casey show the plot hinges on the fact that a photographer taking an IR flash pho...