Inthgued by the multiplicity of solutions of a triplet lens David Shafer devised a problem to seek out the best solution for a four lens design. To simplify things all elements were made of BK7 glass so that the lens would work only at a single wavelength. This is a report on the response of members of the lens design community to this intriguing problem. After a profile of the participants the form of the best solutions will be discussed. The prescriptions for the lenses with evaluated spot sizes below 3 im are given. 1.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.