The surface field Bs ( but not the effective Be one ) is responsible for different processes occuring in the magnetic stars atmospheres. For this reason it is natural that different investigators are interested in working out and improving methods of determination of Bs. Especially great attention attracts the method based on using the multicolor Geneva photometry. Cramer and Maeder have found a dependence between Bs and parameter Z of multicolor photometry wich they use for the estimation of the surface field. But it is necessary to investigate this method before application. Due to this reason we have put the following two problems:
A - The search for stars with a maximal predicted field
B - Examination of calibration of Bs (Z).