Undulator Q-EXAFS with continued scanning of undulator gap is routinely per
formed at the ESRF beamline ID26. The undulator gap is changed at constant
speed while the monochromator angle is changed at variable speed. The flux
loss when doing this, if any, can be kept below 10 % of the photon flux one
would obtain when moving the undulator step by step. Spectra reproducibili
ty is better than 0.1 eV. The acquisition time of a 1 keV scan goes from se
conds to minutes as function of energy, harmonic selected and resolution re
quired. Present limits of the technique and its applications are presented.