Accurate photometry of fast variable objects requires simultaneous measurements of object, sky and comparison star with high time resolution. Additionally, if reliable colours of short time variations are of interest each light source has also to be measured simultaneously in several wavelength regions.

The prototyp of a 3 channel 5 colour photometer fitting these requirements was constructed at the Universitats-Sternwarte Miinchen in 1983 and shall be described in the following. The development of this instrument was carried out in two steps: At first a 3 channel photometer had been designed for observations in integral light. It was successfully tested at Calar Alto Observatory (Mitt. Astron. Ges. 60, p. 474, 1983)