One of the unfortunate aspects of the marketing blurb for these LED torches
is the use of "lumens" as a light output rating. It is very difficult to
compare a 'lumen' rating with a 'candlepower' rating which has been the
usual way hand held spotlights have been rated in the past. As I understand
it, lumens is best use as a rating for an unfocussed light output and
candlepower is better suited for a rating of a focussed light output.
As far as what we're accustomed to in light outputs from spot lights,
consider that many commonly available halogen filament spotlights are rated
at over one million candlepower. No matter how you convert an output rating
in lumens to an output rating in candlepower I would suggest that a
spotlight with an output of a million candlepower would, more than likely,
be brighter than that of a LED torch with an output of 1000 lumens.
The main advantages of LED spotlights over halogen filament spotlights are
in the size of the LED spotlight and the operational time between recharging
of the batteries.
There is definitely no price advantage in LED spotlights if the same light
output is required.
Also, many car headlights have higher lumen outputs than many of the higher
powered LED spotlight torches. Some of those headlights are very annoying
(especially to people developing cataracts) but they don't seem to be
causing a lot of permanent damage to people's vision.
Bob Inglis
Sandstone Point
Qld
-----Original Message-----
From: Peter Shute
Sent: Sunday, May 20, 2012 4:03 PM
To: ;
Subject: Led Lenser Torches for night birding
I'm sure the inverse square law applies, but I wonder if these highly
directional beams are still dangerous at greater distances than we're
accustomed to. Taking directionality to an extreme, lasers are dangerous, or
at least very annoying, from a great distance.
Let's assume we're still talking about human eyes.
Peter Shute
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