In a media release from the CSIRO today, two of their scientists, Dr Piers Barnes and Ms Nic Svenson have won the 2006 Ig Nobel Prize in Mathematics for “figuring out how many photographs to take of a group of people to be confident of getting at least one where no-one’s blinking”. The maths is explained briefly in this Velocity article, Blink-free photos, guaranteed:

Piers then figured out how many shots I’d need to be 99% certain of getting a good one. He found that photographing thirty people in bad light would need about thirty shots. Once there’s around fifty people, even in good light, you can kiss your hopes of an unspoilt photo goodbye.Piers also came up with a rule of thumb for calculating the number of photos to take for groups of less than 20: divide the number of people by three if there’s good light and two if the light’s bad.”

Here’s a graph to that illustrates the number of photos required to be 99% confident of getting a good one:

Photos and Blinks graph