This picture has allegedly been captured on March 3, 1977, at about 14:00, near the river Wedel in the Hamburg area, Germany.
The standard caption offered by several websites who present the image says:
"Herr Walter Schilling observed and photographed this flying disc with a curious rotating, fluorescent periscope-like mast. The object was very close to the ground and was tilted at an angle as it cast a 30 feet shadow on the grass to its right."
Because the close up indicates at least some resemblance to the famous Paul Trent photographs in McMinnville, 1950, this resemblance with the McMinnville photograph is sometimes quoted as reason to believe the picture is a hoax or on the contrary that it is not a hoax.
Actually, Michael Hesemann, a highly controversial German character who published UFO litterature "as journalist, not ufologist," admitted in his book "The mystery of the Unidentified Flying Objects", 1998) that Walter Schilling had sent him a good dozens "primitive Fotocollagen" in 1981 and 1983. In June 1982 Hesemann had already learned of Ground Saucers Watch's opinion that the photograph shows a small model. It was not easy to contact Schilling in 1984, because he was in a psychiatric hospital following legal charges for sexual misbehavior, however, it seems that on August 11, 1983, he met with Michael Hesemann and told him that the photograph show a small model he built and photographed, adding that it was "a very good joke, my friend."
The above picture was published in "Der Stand der UFO-Forschung," (The Current State of UFO Research) by I.V. Ludwiger.
The original of the picture seems to be archived at the MUFON-CES in Germany.
The photograph is not very broadly known. It appears on a 1993 CD-ROM entitled "UFO." This is where the standard caption comes from.