BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="ailevin" data-source="post: 3624061" data-attributes="member: 140149"><p>I am more familiar with studies of night vision, but I expect that many of the same principles would hold.  This  Roger Clark <a href="http://www.clarkvision.com/articles/visastro/" target="_blank">link</a> refers to his book The Visual Astronomy of the Night Sky.  Basically, your ability to detect something depends on both differences in surface brightness, and image scale.  With a fixed size instrument, increased magnification reduces surface brightness but increases image scale, so when observing an extended object, there is an optimal magnification.  Anyway, the binocular is not making things brighter (yes it gathers more light, but it spreads it over a larger area-- surface brightness can only go down). However, you are able to detect contrast differences due to the increased scale.</p></blockquote><p></p>