> From: David Adams
> I don't want to disturb the animals any more than possible
> and so starting hunting around for information on red filters
> and the like. I turned up a very interesting article from
> 1997 based on some research Robyn Wilson did spotlighting for
> various tropical possums:
>
> http://www.jcu.edu.au/rainforest/infosheets/possum_spotlight.pdf
>
> The main points I gather from the article and a bit of other
> reading are:
>
> * A brighter light was more disturbing to the animals.
>
> * You saw _fewer_ animals with a brighter light because the
> light reached the animals before you spotted them. With a
> less intense light, you haven't scared the animals off so
> quickly. (Makes sense - but I'd never thought of this before.)
>
> * Clear, red, green filters - it didn't matter: anything that
> makes the light less intense works.
>
> That all sounds good, but what does it mean in practical
> terms when buying a torch or a spotlight? That's what's got
> me writing in to the list. Dr. Wilson compared a "30 watt"
> spotlight with and without a filter.
I use a 30 W globe with a red filter on a Lightforce 170mm spotlight.
(but I should have bought the smaller 140mm unit) and a 12V lead-acid
motorbike battery. The 30W globe gives significantly longer battery
life than 50W or 100W globes. There is some loss of light, but using
binoculars help significantly.
The Lightforce web site http://www.lightforce.net.au/images/GLOBES.pdf
suggests 320000 candlepower (before filtering).
On a trip last year to FNQ I used small (2 x AA cell) 3W led torch.
(A Fenix unit from http://www.torchworld.com.au/ - forget which)
as I couldn't take a lead-acid battery on the plane and it was too heavy
anyway).
This was surprisingly good.
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