  We present a study of the in-flight performance of the XMM-Newton EPIC MOS
and pn detectors, with focus on the influence of proton flares and vignetting
on the data. The very wide range in the conditions of our sample of
observations, in terms of exposure length and background intensities, allows
the detection of a wide range in the spectra of the proton flares, in contrast
to the hard-spectrum flares proposed by Lumb et al.(2002) or Read et al.(2003)
We also find an up to now unreported contamination in the low energy regime
(E<0.5 keV) of the MOS1 observations, consisting of a significant increase in
the measured intensities in two CCDs at the edges of the detector. This
contamination yields in "bright CCDs" in the observations. Its effect must be
taken into account for the study of sources detected in the affected CCDs. With
respect to vignetting, we present in-flight exposure maps and we propose a
method to repeat this calculation for user-definable energy bands. All the
results presented here, have the goal to enable the study of very faint
extended sources with XMM-Newton, like nearby galactic X-ray halos or the soft
X-ray background.
