When the first automated refractor was introduced in the United States in the 1970s, the instruments required a skilled operator and delivered questionable readings that were difficult to interpret.

An autorefractor helps detect the lens power required to accurately focus light on your retina. It takes a few seconds and requires you to put your chin on the chin rest and look towards the picture ...

Reference Article: Facts about the Yerkes Observatory and Yerkes Telescope. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. Yerkes Observatory, ...