naked eye

Idioms  

1. Sight unassisted by an instrument such as a microscope or telescope. For example, These insects are too small to be seen with the naked eye. This expression was first recorded in 1664.

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Example Sentences

Mercury, Venus, Saturn and Jupiter should be visible to the naked eye but Uranus and Neptune will likely require binoculars or a telescope.

From BBC

Prosecutor Ian Hope said O'Sullivan "essentially ploughed straight into the back of the stationary Nissan, with there being no apparent avoiding action to the naked eye."

From BBC

Heymans says the photographs people often post on Instagram can be "false advertising" because the colours of the Northern Lights are not always visible to the naked eye.

From BBC

It didn’t look big enough for an adult person to live inside, but Danny was learning that there was more to things than could be seen with the naked eye.

From Literature

The scientists who had come in from California and Hawaii weren’t as familiar with the mountain as Crandell and Mullineaux; they didn’t realize with their naked eyes how dramatically Mount St. Helens had changed.

From Literature