  Aims: To understand the contribution of active region and flare plasmas to
the $\lambda$195 channels of SOHO/EIT (Extreme-ultraviolet Imaging Telescope)
and TRACE (Transition Region and Coronal Explorer).
  Methods: We have analysed an M8 flare simultaneously observed by the Coronal
Diagnostic Spectrometer (CDS), EIT, TRACE and RHESSI. We obtained synthetic
spectra for the flaring region and an outer region using the differential
emission measures (DEM) of emitting plasma based on CDS and RHESSI observations
and the CHIANTI atomic database. We then predicted the EIT and TRACE count
rates.
  Results: For the flaring region, both EIT and TRACE images taken through the
$\lambda$195 filter are dominated by Fe ${\rm XXIV}$ (formed at about 20 MK).
However, in the outer region, the emission was primarily due to the Fe${\rm
XII}$, with substantial contributions from other lines. The average count rate
for the outer region was within 25% the observed value for EIT, while for TRACE
it was a factor of two higher. For the flare region, the predicted count rate
was a factor of two (in case of EIT) and a factor of three (in case of TRACE)
higher than the actual count rate.
  Conclusions: During a solar flare, both TRACE and EIT $\lambda$195 channels
are found to be dominated by Fe ${\rm XXIV}$ emission. Reasonable agreement
between predictions and observations is found, however some discrepancies need
to be further investigated.
