Tuesday, 17 August 2010

Dark adaptation 2

Much better than the traditional flashlight and red filter, however, is a red LED (light-emitting diode) flashlight. Its red is purer and deeper, so the division between rod and cone vision is more sharply drawn. LEDs also use much less current, so the batteries last for years. Many LED flashlights for astronomers are now available.

Secrets of Deep-Sky Observing by Alan MacRobert

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