The original version of this paper was written as part of Tim Ahrens’ MA in Typeface Design at the University of Reading in 2007. Tim first became engaged in the issue of optical sizes while he worked on the digitization and redesign of the Leipziger Antiqua (published as JAF Lapture in 2004). Through the project, he realised that although size-specific adjustments were commonly practiced for 500 years of metal type printing, not much documentation was available on the subject. This lead him to research and write about it himself, in the hope that the outcome would become a useful source for practitioners who wish to create fonts with size specific styles. The book looks into type history and perception psychology, and analyses designs by old masters as well as numerous contemporary designers.