The authors have made an experimental study of a five-element afocal lens and find that the magnification, M, depends on the overall voltage ratio, V₅/V₁, in exactly the manner predicted earlier, i.e. M=(V₅/V₁)^-14/. For lenses of different proportions they find that the prediction of a simple scaling law for the focusing potentials is valid. They have extended their measurements to five-element lenses with potential distributions different from those used in the afocal lens and have demonstrated 'true zoom' action in which the magnification can be varied over a range of some 9:1 at a given overall voltage ratio. Measurements made over a wide range of focusing potentials show that the five-element lens could be operated to give constant magnification over an extremely wide range (10⁴:1) of overall voltage ratio or to give constant angular magnification over a smaller, but still substantial range (100:1). The authors present design curves from which the potential distribution required for a specific purpose can be simply obtained.