I think you can't compare owl eyes to human eyes in this discussion.
Owls have 8x the number of rods in their eyes as do humans, rods being the
light sensitive receptor.

In a book on owls I have at home, there is a documented case of a Boreal
Owl that went blind at the Toronto Zoo, presumably from photographers
flashes. (This was some years ago.)I can provide specifics to those that
wish them tonight.

Saw-whet Owl banders, after processing a bird in white light, allow the
bird to adapt back to darkness before release. There is an ongoing study
on the length of time required for this.

-Jamie


>
> In a message dated 3/30/2005 5:45:25 PM Pacific Standard Time,
> owler at sounddsl.com writes:
>
> Spotlight - I have a 500,000 candlepower cordless spotlight. Any
> more candle power is probably harmful, and at observation ranges,
> overkill.
> A 300,000 candle power spotlight would be ideal, but I have not seen one
>
>
> *On bright light/flash:
>
> "...it seems reasonable always to err on the side of caution in these
> matters. The scotopic spectral sensitivity and rate of dark adaptation of
> avian
> retinas are very similar to those of mammals, including ourselves.Thus if
> our own
> dark adapted vision is disrupted by the flash, it is wise to presume that
> the
> bird's dark adaptation will be equally affected. If we are temporarily
> "blinded" by the flash then so will the bird for a similar length of time.
> For
> example, if you knock out a fully dark adapted retina, assume it will take
> up to 30
> min for full sensitivity to be recovered.
> "Remember also that disruption of dark adaptation is never likely to occur
> in
> nature."
>
> * this from
> Graham R. Martin, BSc, PhD, DSc.
> University of Birmingham
> Birmingham B15 2TT, UK
>
> Just thought I'd throw this in the mix.
>
> Cheers,
> Joe Meche
> Bellingham, WA
>
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Jamie Acker
Bainbridge Island, WA
Owler at sounddsl.com