Collectors use their eyes so much. Besides examining coins, there are magazines and newspapers to read, auction catalogs, research. Many collectors, especially older people, wear glasses or some type of corrective lenses.
Has anyone else noticed the vast amount of optical aids used by collectors? Besides glasses or contact lenses for basic looking, there are pocket magnifiers, loupes, perhaps stronger optics. I once met a professional authenticator who told me he used a microscope in his work.
A good number of collectors, I discovered, are interested in astronomy/space science. Naked eye observing is great, but an observed also uses binoculars and telescopes, which come in varieties. There are refracting and reflecting, Dobsonian and catadioptric. And those are just the ones I have known and used. These optics are used to look at planets millions of miles away, stars that are light years away, and distant galaxies.
Numismatists use optical aids to look at coins, large and small, for detailed work. Some may also use different optical aids to observe stars and planets. There is no end to the number of lenses and uses for a dedicated collector.