Snapped at least 5 shots of ghosts on Shadow Moses Island.

Missable.

In order to do this, you must first obtain the Camera. This can be obtained during any of the first four Mission Briefings through the use of Mk. II/III.

Ghosts can first be seen on Shadow Moses Island in Act 4. There are a lot of ghosts, but luckily, you only need to photograph five of them. The ghosts aren't visible, but you can still photograph them. If you want to be able to see them, you must equip the Sorrow Doll, which can be earned during the Screaming Mantis battle in Act 5. Shooting the blue doll in her hand multiple times will cause her to drop it, simply pick it up before she does to receive it.

Below is a video for the trophy, showing the first five ghosts. This is done without the Sorrow Doll. All credit goes to PrimalLIQUID.