Exposures by night with artificial illumination introduce diverse problems:
- Motives and its illumination can only be judged in darkness
- Long exposure times must account for Schwarzschild's law
- Photographic films can shift during long exposure times in film cassettes
- Digital backs should be the better solution, however exposure times of 40 minutes with an aperture of 16 are rarely available
- Therefore above pictures were realized with precision flat field cassettes by Linhof.