The equipotential lines and the trajectories of electrons in a Moellenstedt analyzer are computed. The effects of relativity and the self‐magnetic field of the moving electrons are taken into account. The dispersion, resolution, and caustic position are defined and calculated. The sensitivity of the dispersion and resolution to not only the voltageVapplied to the electrode rods, the electron energyE, the incident angle &fgr;, or the geometrical construction of the analyzer, but also the distanceLbetween the analyzer and detector has been investigated. The caustic position varies strongly with the incident angle and the geometrical construction of the analyzer. The dependencies of resolution on the incident angle and the geometrical construction are significantly reduced in the vicinity of the caustic with the angular spread of the incident electrons remaining the major contributor to the finite resolution.