I was present when one image of three
UFO's over the city in central Europe was taken, 40 years ago.... recently I found that image on one
UFO website, and the event is even mentioned in one of Von Daniken's books..
Basically, it happened like this: One evening couple of my mates gathered on the observatory, and were bored to death.. so one of us decided to do something about it.
He went into a dark room and projected on the wall the piece of paper with three holes on it.. and he took a picture of this.
Then, he went to the window (from where the panorama of city was visible) and took another exposure on the same piece of film (with Exacta Varex, this 35mm camera was capable of multiple exposures without film advance).
The final photo looked VERY good and convincing... but that was it for the evening, the whole exercise was done to prove the concept

However, next evening another guy appeared, who did not have the knowledge of what went on the night before, and someone showed him the photo, saying it was real and taken the night before.. The other guy got very excited.. and he phoned the local papers telling them about
UFO's above the city.. and when reporters arrived, everyone got scared and did not know what to do (we were 16 yo).. so they decided to go along and made up the whole story, which was published next day as a pretty big sensation

There was a lot of "soul-searching" for couple of days later, even the military was involved (because they did not see anything on their radars...). I do not have to tell you that after this article in local paper, there were hundreds of reports and sightings..

The original negative was destroyed (thrown into the stove and burned).
And, since then, I am VERY suspicious and basically dismissive about those reports.. especially today when with the help of PhotoShop ANYTHING is possible..