Green laser pointers on telescopes

I have an 8 inch dobsonian which came with a 9x straight through finder
as well as a telrad finder. I found it difficult and time consuming to
locate DSOs in the sky with this system. I replaced these two items
with a green laser pointer, attached with a bracket (allowing easy
alignment, just like a regular finder) to my telescope. I also got a
9x50 right angle finder (correct-reading) so I could look down instead
of twisting my neck.

I was amazed at how quickly I could find things. The laser pointer
allows me to get to the point of the sky while I am standing up (no
back pain here!) and I often do not need to use the 9x50 finder to
refine my search.

For example, in the Scorpion I know where M4 and M80 are located
relative to Antares and some other stars. I point the laser at the
place they should be and when I look through the eyepiece, they are
almost in the center of view. Also I am able to easily locate objects
close to the zenith without going through bodily contortions and
kneeling on the ground.

I would be interested if others have had similar experiences. Perhaps
people just do not know how useful and easy it is to use a green laser
pointer and there won't be too many responses.

Imagine a star party with everyone using this method. Gross light pollution
and to be discouraged!

Or are you just Trolling?

Regards
Paul
"callisto" wrote in message
oups.com...
I have an 8 inch dobsonian which came with a 9x straight through finder
as well as a telrad finder. I found it difficult and time consuming to
locate DSOs in the sky with this system. I replaced these two items
with a green laser pointer, attached with a bracket (allowing easy
alignment, just like a regular finder) to my telescope. I also got a
9x50 right angle finder (correct-reading) so I could look down instead
of twisting my neck.

I was amazed at how quickly I could find things. The laser pointer
allows me to get to the point of the sky while I am standing up (no
back pain here!) and I often do not need to use the 9x50 finder to
refine my search.

For example, in the Scorpion I know where M4 and M80 are located
relative to Antares and some other stars. I point the laser at the
place they should be and when I look through the eyepiece, they are
almost in the center of view. Also I am able to easily locate objects
close to the zenith without going through bodily contortions and
kneeling on the ground.

I would be interested if others have had similar experiences. Perhaps
people just do not know how useful and easy it is to use a green laser
pointer and there won't be too many responses.

Hi there,

Personally, I'm not sure I'd like the use of green lasers as
finders become common place. I find it somewhat disruptive of
the observing experience. Call it yet another sort of light
pollution :-)

Imagine a field of people observing, many of them using green
lasers. What was a quiet, non-obtrusive experience will now
result in green laser beams criss-crossing the sky interfering
with the nice dark night sky (not to mention messing up anyone
trying to image at that location).

For personal use at your own site .. I guess that's fine. However
I really like the fact that I can be somewhere quietly observing
the sky without anyone knowing I'm there or disturbing them.
If I'm sitting on the deck at night enjoying the night sky I'd
rather just see it, and not a neighbor's Obi-wan Kanobe (sp??)
setup ...

Just my 2 cents .. I'll be curious what others think.

Esmail

PS: FWIW, I have a similar setup as yours. A 9x50 RACI finder, and a
Rigel Quick Finder. I have found this combo to be very effective
on my XT-8 (dob). I don't know your background and how much time
you have spent at the scope, so please don't take this the wrong
way, but perhaps there is a way to further improve on your
technique with the finders?

Esmail Bonakdarian wrote:
Hi there,

Personally, I'm not sure I'd like the use of green lasers as
finders become common place. I find it somewhat disruptive of
the observing experience. Call it yet another sort of light
pollution :-)

Imagine a field of people observing, many of them using green
lasers. What was a quiet, non-obtrusive experience will now
result in green laser beams criss-crossing the sky interfering
with the nice dark night sky (not to mention messing up anyone
trying to image at that location).

For personal use at your own site .. I guess that's fine. However
I really like the fact that I can be somewhere quietly observing
the sky without anyone knowing I'm there or disturbing them.
If I'm sitting on the deck at night enjoying the night sky I'd
rather just see it, and not a neighbor's Obi-wan Kanobe (sp??)
setup ...

Just my 2 cents .. I'll be curious what others think.

I think you're making a mountain out of a mole hill.

Have you ever used a 1-5 mW green (532 nm) laser pointer?

You are talking about a few thousandths of a watt worth of
light. Because of forward/backward scattering, the beam is most
visible to those close to it (or towards it - but if you
are pointing the beam up this shouldn't be a problem). People
more than 15-20 feet away can hardly even notice the beam.
Not really a hazard to pilots either, as the beam quickly
diverges.

The problem is actual light pollution caused by streetlights
and people with floodlights, etc. Not only is this a waste
of energy ( probably comes from burning coal which releases
CO2 and mercury into the environment) it also decimates the
night sky in urban environments. If you want to worry about
something this is it, not people using laser pointers as finders.

I can imagine them being banned or regulated at star parties,
but beyond that most of the stuff you hear about these
pointers amounts to hysteria.

-Eric B

PS Of course, if someone wanted to use a REALLY powerful
laser pointer (likely not legally) as a finder, THAT would
be annoying. But 5 mW green is really not that obtrusive.

I'm aware of the problems at large sky parties with criss crossing
beams. It just wouldn't look right. Also, those doing
astrophotography would have a hard time getting good images, as pointed
out.

However, when you are by yourself or perhaps having a sky party for
grade school kids or showing stuff to your neighbors, I think a green
laser would be hard to beat.

I do have to put myself through contortions to see objects and perhaps
I just have to learn how to use telrads and straight thru finders
properly. For me, standing upright and pointing the laser in the exact
spot you want it, is far better than the standard methods.

In addition I live in a place with a fair amount of light pollution and
high humidity. I was easily able to find M75 in Sagitarius (a kind of
lonely object with my conditions and latitude) by using my 15x50 image
stabilized binoculars in my left hand to find M75 and while still
viewing M75 through the binoculars, I could move the laser pointer to
the exact location. When I looked through the eyepiece it was almost
centered.

wrote:

I think you're making a mountain out of a mole hill.

Well, everyone is entitled to their opinion.

Have you ever used a 1-5 mW green (532 nm) laser pointer?

I have.

Esmail

Esmail Bonakdarian wrote:
Hi there,

Personally, I'm not sure I'd like the use of green lasers as
finders become common place. I find it somewhat disruptive of
the observing experience. Call it yet another sort of light
pollution :-)

Imagine a field of people observing, many of them using green
lasers. What was a quiet, non-obtrusive experience will now
result in green laser beams criss-crossing the sky interfering
with the nice dark night sky (not to mention messing up anyone
trying to image at that location).

I could imagine it, but I've never actually seen it. Plus, my 5 mW
laser can't easily be seen from more than a 20 feet or so from the holder.
I suspect anyone trying to image at a star party is really only wanting
to show off there latest gigadollar purchase from SBIG ;-)

For personal use at your own site .. I guess that's fine. However
I really like the fact that I can be somewhere quietly observing
the sky without anyone knowing I'm there or disturbing them.
If I'm sitting on the deck at night enjoying the night sky I'd
rather just see it, and not a neighbor's Obi-wan Kanobe (sp??)
setup ...

....or the feds coming to bust them for being a laser wielding terrorist.

Shawn


BTW I use a Telrad and generic straight finder on my SCT, and a red dot
POS on my refractor.

Esmail Bonakdarian:
Personally, I'm not sure I'd like the use of green lasers as
finders become common place. I find it somewhat disruptive of
the observing experience. Call it yet another sort of light
pollution :-)

Imagine a field of people observing, many of them using green
lasers. What was a quiet, non-obtrusive experience will now
result in green laser beams criss-crossing the sky interfering
with the nice dark night sky (not to mention messing up anyone
trying to image at that location).

For personal use at your own site .. I guess that's fine. However
I really like the fact that I can be somewhere quietly observing
the sky without anyone knowing I'm there or disturbing them.
If I'm sitting on the deck at night enjoying the night sky I'd
rather just see it, and not a neighbor's Obi-wan Kanobe (sp??)
setup ...

Just my 2 cents .. I'll be curious what others think.

I have to agree with the "mountain out of a mole hill" reply. The OP
was obviously talking about private observing, not a star party, so a
"field of people observing is" not relevant. And none of my neighbours
sits on the deck at 03:00...

In short, anyone who wants to use a green laser in the privacy of his
or her own bedroom ought to be free to do so, though one does have to
be conscious of the brownshirts in this day and age.

Davoud

--
usenet *at* davidillig dawt com

I've seen green laser streaks from maybe 50m away, at the Table
Mountain Star Party in Washington state. The beams are obvious but not
glaring. You don't have to use averted vision to see them. I doubt an
incidental sweep of a beam across a field of view would screw up a
long-exposure film photograph (I don't know for CCD, but suspect even
there the complaint is based on overcautious, untested theory), or
indeed even be visible to the eye in a scope.

It would certainly be an annoying distraction for naked-eye observers.

Two items to consider

1) I built a 0.5mw He-Ne laser back in 1969 as part of a science fair
project. That laser would go well over 1 a mile and diverged to the
size of a small hoola-hoop at that dstance. The beam was easily visible
from behind the laser at that distance on a dark nght (we beamed it
against a barn across the fields from the school). From the barn
looking back, it was extremely evdent and stood out like a "sore
thumb".

2) There have been articles in the US about lasers being beamed at
airplanes as part of a terrorist threat to temporarily blind or
distract pilots. Lasers were actualy shined into the cockpit of a
commercial plane (not from a terrorist group but someone goofing
around) a few months ago, and that elicited some very serious
reactions. I would be VERY CAREFUL where and when you used it. Here in
te US, you might get a very "undesirable" response.