A short lesson on elements from the Periodic Table that are used in photography...

Magnesium: used in (old) flash photography bulbs
Lanthanum: used in lenses for cameras and telescopes.
Also used by the motion picture industry in lighting and projection.
Palladium: used in electronic contacts, and computers.
And of course used in platinum-palladium printing for photography.
Silver: used in film, photo printing papers, and small batteries
Gallium: used in LEDs (which are found in some cameras and light meters)
Germanium: used in wide-angle lenses
Selenium: used in (early) light meters, photocopying,
and as a toner for photographic prints
Polonium: used in anti-static brushes
Krypton: used in high-speed photo flashes

(Window-box display photos were taken at the Tellus Science Museum in Georgia