The members of LICHTFAKTOR use light to give expression to their creativity. They take advantage of a variety of light sources to produce photos and videos in cities by night.

The Cologne artists’ collective, consisting of VJ $ehvermögen (photographer and VJ since 1997 with many years of experience in the event field) and JIAR (communications designer and graffiti artist), experiments with the possibilities yielded by bulb (long-term) exposure and painting. Their aim is to explore all aspects of “lightwriting” and to develop it further. The LICHTFAKTOR crew intentionally uses the entire space in which a particular work is produced and integrates it into their photos and animated films in such a way that it’s not just a backdrop but a part of the work itself.

Here they explain how to do it :

this are the basics:
to get the best results you need a tripod. the exposure should be around 10-30 sec. or longer if needed. stay in front of the camera and do your writing. to not overexpose set the camera to about iso100, and close your aperture as much as possible. if there is still too much light, you might have to use a nd-filter. it is always nice to integrate the surrounding into your picture.

we use flashlights, biking-lights and flashing LED lights they all work with batteries, so that we are mobile, you also get nice results with fireworks & torches .
there are 3 different type of lights we use:

Xenon: makes a warm golden light.
LED: makes a thin precise line.
Cold Cathode: thick line/fat cap.

but the best results you get by experimenting, use filters and things which reflect light…

Spotted via Abduzeedo