Mounted search and rescue

["Barry Wells" <barrywells@tds.net>]

So are you saying you have night vision?

-----Original Message-----
From: msar-riders-bounces@lists.ibiblio.org
[mailto:msar-riders-bounces@lists.ibiblio.org]On Behalf Of Una Smith
Sent: Sunday, March 14, 2010 9:53 AM
To: Mounted search and rescue
Subject: Re: [MSAR] BackPack Question


Barry Wells wrote:
>Why would you not use a flashlight?

So that my eyes are fully dark adapted and I can see far more of my
surroundings.  Using a flashlight, even without shining it in my
eyes, severely reduces dark adaptation.

I used to help catch bats at night.  We would sit in the dark for
an hour, then turn on a headlamp to extract the bats from mist nets,
measure the bats, fit leg bands, and record data in a notebook.
Then we would turn off the headlamp and sit in the dark again.  For
the first 30 minutes or so we would be blind.  Because our headlamp
use ruined the bats' dark adaptation, it was not safe for them to
be released into the night.  We kept them in cotton bags hung on a
bush, and released them at first light of dawn.

People who are nightblind must use a flashlight or other light to
see anything at night.  Advanced age contributes to progressively
poorer night vision, but some people are nightblind from birth.

        Una Smith
        New Mexico
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