Hi
Peter,
Yes, they did use lenses. According to
Wikipedia,
The earliest written records of lenses date to Ancient Greece, with Aristophanes' play The Clouds (424 BC) mentioning a burning-glass (a biconvex lens used to focus the sun's rays to produce fire).[7] Some scholars argue that the archeological evidence indicates that there was widespread use of lenses in antiquity, spanning several millennia.[8] Such lenses were used by artisans for fine work, and for authenticating seal impressions.However, in the case of this particular coin the fabrication process was even more impressive than you might imagine. Not only did they use lenses, but they trained swanstriches to engrave self
portraits using lenses and mirrors. Hence, the magnifying
glass appears along with the swanstrich in the
reverse image. As a final note, the reason that the left
type is more common is because there are more right handed swanstriches than left handed.
Regards,
EB