What practical stargazing technique utilizes the higher sensitivity of the eye's peripheral vision for observing faint nebulae?

Answer

Averted vision, by looking slightly beside the object.

Peripheral vision contains more rods, which are better suited for detecting low levels of diffuse light, allowing fainter objects like nebulae to be perceived when one looks slightly away from the center of vision.

What practical stargazing technique utilizes the higher sensitivity of the eye's peripheral vision for observing faint nebulae?
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