Your suggestions re. infinity focus make eminent sense. Unfortunately, I have astigmatism as well and am, therefore, precluded from using binoculars without spectacles. In fact the 1980s Carl Zeiss Jena brochures used to warn against users with "heavy ametropia" from using their binoculars without spectacles. Given the poor eye relief of their Jenoptems, one had frequently to ignore this warning, till increasing myopia and astigmatism made viewing without spectacles unprofitable.