Photographing the Brocken spectre

The Brocken spectre of the photographer, consisting of two penumbral (partial) shadows, due to the double headlight of a car illuminating the fog. Where the two shadows overlap, the shadow is umbral (total).

The brocken spectre is basically a shadow (the observer's shadow) cast on and in a cloud (fog). Because the cloud is not an object with a sharp boundary, but more or less transparent to some optical depth, the shadow figure will be a three-dimensional image cast not only on the cloud but also in the cloud.

Due to perspective misleading you in estimating dimensions, the Brocken spectre, which is just your shadow, will look much bigger than you are. You see a distant figure in the fog, about at the distance where the fog becomes opaque. If the light source is far away, that figure is as tall as you are, and hence, due to perspective, properly imaged in the fog. However, because all the shadow parts are rays emerging from you into that distant shadow figure, it looks as if the distant figure does not decrease in angular extend with distance as much as perspective would suggest, and hence looks bigger.

Where to look for the Brocken spectre

Brocken spectre with hints of a glory around it, and part of fog bow to the left

The spectre is best seen in mountainous areas, when you are on a mountain ridge and near the top of a cloud or fog layer. The sun has to be strong enough to cast your shadow into the cloud. You will also see a colorful glory surrounding your shadow figure.

If you don't live near mountains or hills, you might have a chance to see the spectre not long after sunrise, when it is foggy (but not so foggy that the sun is obscured). That situation typically doesn't last long, since if the fog is thin, it will evaporate quickly.

Otherwise, you can easily create the Brocken by an artificial light, whenever there is fog. Car headlights do well, although you will see a double figure this way (try to block one of the car headlights then). Walk forward about 100 yards or less (depending on the fog transparency and the brightness of the light). You will see the brocken spectre, a glory, and a fog bow (usually with secondary fogbow and supernumeraries as well).

Photography

Fun with fog! You just need a car and a foggy night, to make visible the primary & secondary fogbows, supernumerary fogbows inside primary, the glory, and the Brocken spectre. This photo shows the complete 360-degree round primary fogbow, a rare sight in nature.

Photographing the brocken spectre, glory and fog bow is as easy as aiming your camera, metering the light, and taking a picture. At night, or at low light levels, you will want to use a tripod. For the lens I'd recommend a 50mm to 80mm or so capture the shadow figure. Keep in mind that with a time exposure at night, you should stand dead still for some minutes, right behind the tripod and camera, because the Brocken figure moves with you. Otherwise, you will photograph the brocken spectre of the camera and the tripod, which looks less interesting.

Other things to observe

Try waving your arms while you observe the shadow figure; you will see that if your arms or legs are oriented to or away from your eyes, the (more or less planar) shadow your arms casts into the fog you will see edge-on, and see a darker shadow ray emerging from you. This is even better visible when you observe the shadow cast by the tripod legs: you will only see the shadow rays when you look from behind the tripod, so your eye is in the plane of the shadow cast by the (linear) tripod leg.

The camera's Brocken spectre. The sharp shadow rays at the top are caused by the camera's film rewind lever, viewfinder prism, and wind lever, respectively.

If you stand still, the shadow will still appear to move. This looks eerie, and gives the Brocken spectre its ghostlike appearance. The dynamic shadow is caused by denser and less dense areas of fog moving by the wind, through your shadow rays. Where the fog is denser, the optical depth of the fog is less, and the figure will suddenly appear bigger in that place, because it is closer to you.

The appearance of the dynamic three-dimensional shadow is something which may startle you at first sight; the optical effects at play are very interesting, educational, and fun to experiment with!