  CCD photometry in the V band is presented for 7 field RR Lyrae stars selected
from a sample of eight variables which, according to data collected in the
literature, are expected to be {\it ab}-type pulsators, to have short periods
and hence high metallicity, and to be located at high {\it z} from the galactic
plane. New periods and epochs are derived for them. The new periods are only
slightly shorter than the values published on the last edition of the General
Catalog of Variable Stars (GCVS4). Instead, in six cases our amplitude of the
light variation is significantly smaller than that published on the GCVS4, and
in at least three cases the actual pulsation appears to be in the first
harmonic rather than in the fundamental mode. All the suggested {\it c}-type
pulsators show variations in the amplitude and/or quite scattered light curves.
Possible explanations are given. From a spectro-photometric analysis of the
sample, only DL Com is confirmed to pulsate in the fundamental mode, to have
short period, and to be located at relatively high {\it z}. A single object
cannot be taken as evidence for a significant metal rich population at large
distance from the galactic plane.
