Analysing a 'Ball Lighting' Photograph

Colin Bord
Letters, Magonia 13, 1983

The frequently published Roy Jennings 1961 photograph of alleged ball lightning is once more causing controversy and confusion (Magonia 12). Stuart Campbell [1] and concluded that the picture was not intentionally faked by Jennings, but his faulty camera had superimposed a trace of light across the film after he had finished taking his picture of a normal lightning flash and as he moved away from his bedroom window.

It is my experience that such 'lazy' camera shutters frequently produce these anomalous light effects and cause inexperienced photographers to claim all manner of psychic and atmospheric manifestations.

In his letter in Magonia 12, Paul Devereux makes some erroneous assertions regarding the photographic process which to the inexperienced would appear to give authenticity to the Jennings ball lightning claim. To prevent the confusion being even further compounded, I should like to bring the facts to the attention of Magonia readers.

(1) Devereux says in effect that because the image of the houses and telephone kiosk, are not blurred by movement, the trace of light could not be caused by a moving camera. This is incorrect. The reason is simply that the light source is hundreds of times brighter than the light reflected from the houses and the light coming from the telephone kiosk. According to Campbell's report (mentioned above), the photographer held his camera against the window and opened the shutter on a time exposure, waiting for a flash of lightning. After he saw a flash he closed the shutter. Therefore, during the time exposure the dimly lit houses and telephone kiosk would have long enough to register an image on the film, and the brilliant street lamp would overexpose and cause an area of 'flare', which is what the picture shows.

When the photographer moved his camera away from the window, erroneously thinking the shutter was closed, the brilliant street lamp was bright enough to cause a streak of light to register on the film, but everything else in the scene is so dim his article. Anyone with a camera which has a 'B' setting on the shutter dial can try it for themselves. All photographic images are subject to a law which can be expressed as: strength of photo image = intensity of subject illumination x length of exposure time. This means that a dimly lit object exposed for a long time will produce the same strength of image on the film as a brightly lit object exposed for a short time.

(2) The perspective effect which Devereux sees in the light trace is a likely source of confusion, but it is a product of the same photographic effect as the confusion dealt with above. If the camera is moved rapidly, the image of the intense light source will register as a faint and attenuated line, and when the camera is moved more slowly the light will have a longer time in which to affect the film and will therefore leave a wider and brighter trace. This is supported by the visible trace in the picture: the straight, horizontal lines of movement show a faint, thinner image where the camera moved quickly, and where the camera slowed to change direction the image is brighter and wider.

The pulses of light are caused by the alternating current of the street lamp, pulsing at 50 cycles per second. Studying the picture, one can easily see where the regular pulses are 'stretched out' where the camera moved rapidly, but 'crowd up close' as the speed of camera movement slows. Throughout the whole trace the light pulses rema1:n horizontal and parallel to the light tube in the street lamp, clearly indicating that they are images of this source of light, By counting the number of pulses throughout the whole trace one can estimate the length of time which the whole manoeuvre took, which appears to be a little less than two seconds.

So this apparent perspective effect of foreshortening, frequently used by artists to simulate three-dimensional space, is in this case purely a photographic effect. Devereux has interpreted the picture with the eye of the creative artist, but what is required here is the eye of the analytical photographer.

(3) At the time of expose there was clearly mains electricity in the area. I have checked with a telephone engineer who assures me that all telephone kiosk illumination is direct from the mains (the power for the telephone itself is quite independent), and the telephone kiosk in the picture is undoubtedly illuminated. Also, lit windows can be seen in the row of houses; an illuminated first-floor window in the dark area on the right and the window immediately below the light source. Another relevant point is made in Ball Lightning and Bead Lightning: Extreme Forms of Atmospheric Electricity by James Dale Barry (Plenum Press, 1980), who writes that 'Davies and Standler (Nature, 1972) ascertained from the Electricity Board that it (the street lamp) was in fact illuminated at the time of the recorded event', and that by photographing a street lamp Davies was able to reproduce the visual effect seen in the photograph.

Other points of interest are that the photograph as published in Earthlights is reversed when compared to the daylight photographs of the site reproduced with Campbell's article, as well as all the other published reproductions. The best reproduction of it I have seen is on page 41 of Photographs of the Unknown by Rickard and Kelly (1980), a book which every Fortean must surely possess, and which also contains other interesting photographs of ball lightning and various other light traces. In this reproduction of the photograph the dark area down the right-hand side of the picture is very evident and is generally considered to be the out-of-focus side of the window frame. As the light trace goes right across this area it clearly indicates that this was produced within the camera and was not something in the sky recorded during the time exposure.

Finally, if this trace had been caused by ball lightning, then it shows that the ball lightning moved below the level: of the rooftops and down to the ground-floor window level before moving to 'earth' itself on the street lamp. It is generally stated that electricity finds the shortest path to earth, but this does not seem to have happened in this case. Also, I can find no other record of ball lightning which was seen to have a regular liqht pulse. Do any such records exist? In view of the several competent and independent reports on this photograph which have been published in the past, all of which show that the effect was a result of camera malfunction, it is surprising that it is still being presented as an example of ball lightning.

1. The British Journal of Photography, 23 October 1981