Photographs are taken using either a Bronica SQA 6x6 or Mamiya 1000s 6x4.5 medium format camera. Additional illumination underground and inside buildings is provided by a Metz 45CL-4 electronic flash. The dedicated Metz battery pack only gives a limited number of flashes, so the flash is run from a home made battery pack that comprises of 6 'F' type cells.

The film used depends on weather conditions, the subject matter and how I feel on the day. I initially started taking colour photographs using Fuji Provia 100, but then discovered the delights of Fuji Velvia 50 just before it was withdrawn. I'm now using Velvia 100. Black & White photographs originate on Ilford film, mainly Delta 100 & 400, although I've started using FP4+ and HP5+. Originally underground and internal photographs were taken on Kodak Portra 400 negative film, although I've now made the switch to Fuji Provia 400 so I can project them.

Underground and night photographs are taken using 'open-flash' photography. The camera is positioned on a tripod with the shutter locked open using either the 'B' or 'T' setting. Whilst the shutter is held open it's possible to move around in the dark with a flash gun to gradually build up the image.

By illuminating different areas of the scene in sequence, and with careful positioning of lighting angles, it is possible to fire the flash gun a number of times whilst actually standing within the picture, without ever appearing in the frame!

An article written by Nick Catford describing these techniques can be found on the Bunkertours website.