A new article has just been published in the Journal of Applied Crystallography on a mathematical method for the selection of the optimum collimation parameters:

Wacha, András. “Optimized Pinhole Geometry for Small-Angle Scattering.” Journal of Applied Crystallography 48.6 (2015): 1843–1848. DOI: 10.1107/S1600576715018932

This is the method we routinely use on CREDO to obtain the highest possible flux while the beam is free from parasitic scattering.

The paper can be found at the website of the journal (with supplements). The manuscript, according to the author self-archiving rules can be found here.