I am usually working with electron microscopy images of macromolecules, and we use reciprocal distance units [1/Angstrom] for units in Fourier Space. A repeating signal every e.g. 10 Angstrom would correspond to a Fourier Space signal at 1/10 [1/Angstrom].
I was surprised to find out that the q-value in small angle X-ray scattering (SAXS) is not defined in the same way. Units are the same [1/nm] or [1/Angstrom], but there is a factor of 2pi in there.
Can a person in the SAXS field explain me the reason for this convention, which seems overly complicated to interpret the actual values in scattering curves in terms of real-space distances?