SUBVERSION: mmchdm nejedná se o single shot fotografii.
This image was created by Century Magazine photographer Dickenson V. Alley using "trick photography" via a double exposure. The electrical bolts were photographed in a darkened room. The photographic plate was exposed a second time with the equipment off and Tesla sitting in the chair.
In his Colorado Springs Notes Tesla admitted the photo was a double exposure: To give an idea of the magnitude of the discharge the experimenter is sitting slightly behind the "extra coil". I did not like this idea but some people find such photographs interesting. Of course, the discharge was not playing when the experimenter was photographed, as might be imagined!