When DH and I are riding tandem, I'm designated photographer. We have an Olympus that is waterproof, crush proof and drop proof (1.5m). Haven't tested the drop proof part (thank goodness) however I just stash it is his jersey pocket in front of me and I take photoa all around- very funny in a paceline looking backwards!

DH is also very good at taking photos one handed while riding on his own.