The generalized extinction factors for a set of strong reflections as a fun
ction of wavelength are obtained by indirect measurements. The experiments
are performed on a crystalline system that satisfies the geometrical requir
ements imposed by theoretical models developed for a finite perfect crystal
. With increased perfection, represented by a reduction in the width of the
mosaic distribution function from three to one thousandth of a degree, the
experiments give results that approach the predictions from the theory. Th
e present procedure utilizes measurements of the integrated diffracted powe
r of a weak reflection for scaling the strong reflections, hence non-measur
able wavelength-dependent factors are assumed to be eliminated.