A comprehensive test facility has been set up at the Royal Greenwich Observatory for the evaluation of fibers in astronomical applications. Particular emphasis is placed on the performance of fibers at the fast focal-ratios delivered by current prime-focus systems. Recent work carried out at the facility has included a series of experiments on image-scrambling in fibers, and results from these are highlighted in the paper. A probable mechanism for the observed effects is described. Finally, characterization tests on some less-conventional fibers are reported, and possibilities for future work outlines.