Well this was not a one time experiment. We have pointed them up and if
you walk away it gets hard to see.
I am sure the transparancy has a lot to do with it. After all, you cannot
"see" the photon beam. It has to reflect off of something. But there has
to be enough reflected photons to get your photoreactive cells attention.
Same with ccd. There has to be enough photons traveling toward the cam to
get over the sensitivity threashold. i.e. it has to be in the same place
for awhile.
---------
Phil Chambers [ptchamb@No-Spam] (S.F. Bay Area - Calif. USA)
On Fri, 30 Jan 2004, Richard Crisp wrote:
>
> ----- Original Message -----
> From: "P T Chambers" <ptchamb@No-Spam>
> To: "The Astronomy Connection" <sf-bay-tac@No-Spam>
> Sent: Friday, January 30, 2004 4:43 PM
> Subject: RE: [TAC] Green Laser Ptr as a Finder -- NOT
>
>
> > I, we, have noticed that if you are standing very far away from the laser,
> > you cannot see the beam. (not true on some of the souped up ones).
> >
> > Not sure why other than you are looking "crossways" to the beam and it
> > isnt very thick. If you are close, then the view is diagonal through
> > the beam so you can see it.
> >
> > That is why you see people "crowding" around the guy with the laser, it
> > gets pretty faint if you are very far away.
> >
> > The reason I said 30 - 50 feet is that is about how far the second guy is
> > away from you at a star party. I am assuming that if you were "next" to
> > an imager, you would not do it at all.
>
>
> I'd expect the degree to which it is visible is largely dependent on the
> transparency of the air. If there is a lot of smoky haze around or dust etc,
> then it is more likely to show up. If it is going through a vacuum, forget
> about seeing it. Maybe the non-scientific experiment Leonard and I did at MB
> was during a time of excellent transparency? Also it was some time back when
> the green lasers first appeared. Perhaps the one Leonard had didn't light up
> the sky the same as Paul's? Or maybe my red filter was in place at the time
> and I'd not see the green light period. I think I was using my FSQ that
> time, but it is possible I was using the C14, I just don't remember.
>
>