My Life as a Geek

Me and the World's Smallest Telephone (as verified by the Guinness Book of World Records) back in 1980.

Once upon a time, back in the days of film, time exposures (like of the picture below, which was taken at 2:00 AM using a 20-minute exposure) were very much a trial-and-error process.  It was difficult to know how long to keep the shutter open, as the light was too low for the camera's meter to measure accurately, and even if you had a Sekonic handheld light meter (famous for ultra-low-light sensitivity) you still had to account for something called film reciprocity, a property where film would become less sensitive to light the more light hit it.