This paper is primarily concerned with the effect on the line profile shape and intensity of the angle &phgr;, the angle made by the projection of the electron velocity vector on a plane perpendicular to the instrument axis at the source with the radius of the source point. Quantitative results are quoted for several geometries. The line profile, expected intensity, and optimum source size for a commonly used slit geometry utilizing an entrance slit for take‐off angle selection is found to differ significantly from previously quoted results, the intensity for the same half‐width for optimum source size being 46% of the earlier work. A new slit geometry consisting of an additional baffle near the source which restricts &phgr; is discussed and is found to improve the expected intensity for the same line half‐width by 24% for an optimized Hubert slit system which is already found in this paper to be 28% better than the best of previous slit geometries. Finally, a geometry which selects &phgr; properly is shown to remove all dependence on source size from the resolution.