The Nikon SLR FM2 Camera was used by Ray Stantz during the New York City Public Library scene.
Use
It was used while Peter was trying to communicate with the Library ghost. It is unclear if the Camera was successful in photographing her, however from this research done during the Library Ghost encounter helped them to figure out how to capture and store ghosts.
Leather Case
The Leather case (aka: Nikon FM2 FE2 FE Camera Leather Case) is also seen on Ray and is sometimes mistaken for another unknown prop.
External Links
Gallery
Screen Cap of the Nikon SLR FM2 Camera and Leather Case
Screen Cap of the Nikon SLR FM2 Camera and Leather Case
Screen Cap of the Nikon SLR FM2 Camera
Screen Cap of Ray running with Nikon SLR FM2 Camera and Leather Case
Screen Cap of Ray with Nikon SLR FM2 Camera and Leather Case talking to Peter after the events of the Library.