On 24 Mar 2005 at 7:57, Dave Kruger wrote: > I don't know what the change is in iris opening with age -- > maybe someone else on Paddlewise will It varies a lot. It is also easy to measure. Get a ruler with a millimeter scale and stand in front of a mirror. The light level should be what you are interested in (very bright for daylight, very dim for nighttime). Let your eyes get used to the light and then look at the reflection of your pupil with the ruler held close to your eye. > You want a unit with a large enough exit pupil to match your > largest iris opening in dim light ... but anything larger is > wasted. True on land in dim light, but not necessarily in daylight in a moving kayak. If the exit pupil is larger than your eye's pupil then you can tolerate a moving eyepiece a bit more than if the exit pupil is small. You're looking through a little hole - the bigger the hole, the more your head can move relative to the hole while still allowing you to see through it. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Thu Mar 24 2005 - 09:28:03 PST
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