I always thought that the reason people look so grim in antique photos is because it would have been exhausting to hold a smile for long exposures that I imagined were required by ye olde cameras. Nope! From the always-informative Smithsonian magazine:
…Exposures from the early days of commercial photography only lasted about 5 to 15 seconds. The real reason is that, in the mid-19th century, photography was so expensive and uncommon that people knew this photograph might be the only one they’d ever have made. Rather than flash a grin, they often opted to look thoughtful and serious, a carry-over from the more formal conventions of painted portraiture, explains Ann Shumard, senior curator of photographs at the National Portrait Gallery.
According to Shumard, it wasn’t until Eastman-Kodak founder George Eastman’s 1888 invention of the mass market portable camera that informal snapshots of smiling people became common.
“Why Don’t People Smile in Old Photographs? And More Questions From Our Readers” (Smithsonian)
image: Eugene Pelletan portrait c.1855 by Gaspard-Félix Tournachon