Hi Eric,
Happy New Year.
Some of the guys here routinely take them up to Coona and out to Ilford.
As you can appreciate, you point them up, they measure the amount of
light and they give a number. When we have compared one site from another
or the same site with two different meters or the same site measured in
a few places on the sky, one of the things missing is any sense of the
error bars.
The guys have the original versions of the unit and the readings they provide
some argue are flawed.
As many of us from the Southern Hemisphere will testify to when visiting the Northern
Hemisphere, one of the first things we say when we look at dark northern
skies is, "Where are all your stars?".
Down here at the southern latitudes you and I enjoy, the Milky Way passes
overhead and the very bright core of the Milky Way passes overhead at the
zenith. By comparison, at latitudes such as the south of Texas, Scorpius
and Sagittarius come up over the horizon in the south and only reach an
elevation of about 30 degrees. When you look north, there are large conspicuous
areas of black and it is little wonder birds manage to navigate by Polaris at it
sits in a comparative sea of nothing.
So chances are when one is in the Northern Hemisphere, when you point the
device up, there is a larger possibility of getting a reading from a dark patch
of sky. However here, all those damn stars, bright nebulae, globulars and the
Gegenschein and the like seem to get in the way and wreck the reading, so if
one does not take care, you might get a number from your favourite dark sky
site that a guy in Hong Kong can better from his apartment block balcony.
So one has to be careful when taking a measurement to compare apples to
apples as from what I understand, they don't differentiate between light pollution
and starlight.
The newer model with a dash L (-L) suffix apparently has a narrower
detection cone, which may be better suited for these latitudes.