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="elkcub" data-source="post: 3333042" data-attributes="member: 14473">Tobias,  To keep this as simple as possible, your photographs appear to simulate a nighttime comparison when the observer's pupils are open to at least 42/8 = 5.25 mm.  Under those conditions the 8x42 Leica transmits 72% more light than the 8x32 model (5.25^2/4^2 = 1.72), which would account for why its camera image is brighter.  The comparison is most appropriate for astronomers.Following the same reasoning, birders operating under daylight conditions typically have 2-3 mm pupils.  Hence, in order to simulate such a daytime comparison, it's necessary to stop down the binoculars to a common exit pupil size, e.g., 2.5 mm.  I presume this is the same stopped down condition you mentioned with regard to your own daylight observations.  Perhaps you'd like to comment on whether Chosun and I are reading this correctly.  Henry has commented often about how to <a href="http://www.birdforum.net/showthread.php?p=3266980&highlight=brightness#post3266980" target="_blank"> stop down binoculars</a> to make similar comparisons for similar reasons. Ed</blockquote>