From Wired:

IN THE SUMMER of 2013, when documentary filmmaker Laura Poitras was shooting a still-secret NSA leaker named Edward Snowden in a Hong Kong hotel room, she took security seriously. She’d periodically transfer her footage to encrypted hard drives, and would later go so far as to destroy the SD cards onto which her camera recorded. But as she watched Snowden through her lens, she was haunted by the possibility that security agents might barge through the door at any moment to seize her camera. And the memory card inside of it remained dangerously unencrypted, full of unedited confessions of a whistleblower who hadn’t yet gotten his secrets out to the world. “When you’re in the field filming and your camera is taken by authorities, that footage is completely vulnerable,” Poitras says. “That’s where encryption is really needed.” Read the entire article

This is something I’ve never personally thought of, but seems to be something that should be taken seriously.

The list of filmmakers can be seen in the open letter written to Canon at the Freedom of the Press Foundation website.