Optimal third order aberration balancing in zoom lenses

Third order aberration balancing in zoom lenses can be understood with stop and conjugate shift theory because each group may experience a changing relative stop or conjugate position through zoom. Despite the perceived complexity of zoom lens design, experienced designers have speculated that an optimal third order aberration balance often exists for a given design problem. To explore this idea, we optimize the aberration contributions of each lens group using an algorithm based on a method initially proposed by H. H. Hopkins. We test the method on paraxial layouts extracted from patent zoom lenses and compare them to the aberration balances present in the patent design. We find that in many cases, these aberration balances are very similar. This suggests that for a given paraxial layout, there is a near-optimal third order aberration balance. We discuss the implications of this idea on the zoom lens design process.