English: Distance from the central trajectory at the exit of a hemispherical electron energy analyzer depending on the electron's kinetic energy, initial position within the 1 mm slit, and the angle at which it enters the radial field after passing through the slit. Dispersion is nearly linear in energy, linear in initial position, and quadratic in angle. The latter two map into energy channels of the detector, spoiling the resolution. Calculation was done for the Rp=100 mm analyzer. Note orders of magnitude different scales on the vertical axes.