In addition, Metz mecablitz 15 MS-1 digital learns autonomously in the conventional slave mode! Its learning function ensures that the small slave flash is reliably triggered every time by the flash integrated in the camera – even if this sends out a ranging pre-flash. In individual cases, this specific cooperation is attained by trial triggering in slave mode. In this case, the light amount emitted can be varied across 6 light levels.

А если взять 2 колечка, то получится система освещения из 2х отнюдь не точечных источников. Правда, как я понял, мощность придется руками задавать.