  We focus on short--period eclipsing binaries that belong to a class of
Cataclysmic Variables (CVs). They are known as polars and intermediate polars,
closely resembling their prototype AM Herculis. These binaries consist of a red
dwarf and a strongly magnetic white dwarf, having orbital periods of only a few
hours. Monitoring eclipses of these typically faint sources demands high-time
resolution photometry. We describe the very recent results obtained for two
CVs, HU Aqr and DQ Her, which were observed with the Optical Pulsar Timing
Analyzer (OPTIMA). The new observations of HU Aqr confirm that the O--C
(Observed minus Calculated) diagrams exhibit variations known for this binary
which can be explained by a single, massive Jupiter--like planet, possibly
accompanied by a very distant companion.
