The “Image Fulgurator” is a device for physically manipulating photographs. It intervenes when a photo is being taken, without the photographer being able to detect anything. The manipulation is only visible on the photo afterwards.
In principle, the Fulgurator can be used anywhere where there is another camera nearby that is being used with a flash. It operates via a kind of reactive flash projection that enables an image to be projected onto an object exactly at the moment when someone else is photographing it. The intervention is unobtrusive because it takes only a few milliseconds. Every photo another photographer takes of an object at which the Fulgurator is also aimed is affected by the manipulation. Hence visual information can be smuggled unnoticed into the images of others.
Technically, the “Image Fulgurator” works like a classical camera, though in reverse. In a normal camera, the light reflected from an object is projected via the lens onto the film. In the “Image Fulgurator”, this process is exactly the opposite: instead of an unexposed film, an exposed and developed roll of slide film is loaded into the camera and behind it, a flash. When the flash goes off, the image is projected from the film via the lens onto the object. Due to the similarity of the two processes, the Fulgurator looks like a conventional reflex camera. As soon as the builtin sensor registers a flash somewhere nearby, the flash projection is triggered. Hence the projection can be synchronized to the exact moment of exposure of all other cameras in its immediate vicinity. Via a ground-glass screen, it is possible to focus the projection and to position it on the targeted object.
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https://archive.aec.at/prix/showmode/12122/ (12.06.2022)