Camera used is a Minox aka the spy camera. The ring on the end is for a lanyard which is stretched to the paper thus assuring the proper focal length because the camera cannot be focused.
The papers photographed were labeled Secret. The three levels of classification are Confidential, Secret, and Top Secret. Therefore, the papers were not even the highest level of classification.
The FBI photographing the dusted fingerprints is not enough for identification. They must be lifted with fingerprint tape and then read for identification and classification.
The photos Dr. Fields risks his life and trashes his country for turns out to be a basic Second-Order Schroëdinger equation found in any undergraduate physics text.