A camera is often brought along by agents on missions in their favorite canon locations. They then proceed to take many photos of everything they see, sometimes spending extra time in the continuum after they should have already returned to HQ.
Cameras are occasionally an agent's best friend. This would be because you cannot take photos of your favourite canon locations, canon characters, or even of the look on that Mary Sue's face as your partner manages to behead her with their favourite weapon, with the remote activator, the CADs, the neuralyzer, or even your favourite weapon, and good luck getting the console to cooperate with anything you plan.
Some agents are camera-mad enough that they are considered secondary weapons for the agents in question. They are rarely seen without a camera.
Other agents, particularly those with coworkers that view them as Lust Objects, such as Suicide, have had to deal with cameras aimed at them due to the Multiverse Monitor and its nefarious Page Three.