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Old 04-04-2019, 03:50 AM
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skysurfer
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Laser pointer as finder for Dobson ?

This should work with lasers as faint as 1mW when you look close to the telescope (due to legal <1mW limitations in NSW and VIC). And obviously not close to airports in any part of the world.

On another forum I read this tip.
Remove the eyepiece and shine a laser pointer into the barrel via the secondary on the primary.
When viewing close to the beam to the sky, the laser always points to the same part of the sky, regardless which part of the primary it hits when moving the laser in the eyepiece socket (unless you point beside the secondary).

I tested it, but with a brighter one. Indeed, I could point it exactly to a location in the sky and when I popped in an eyepiece (24mm Pan in a 400mm f/4.5 = 75x or 0.9 deg TFOV), the selected object was in the field.

Strangely I did the same test with my 80mm f/6.5 but the laser pointer moved inside a circle of 1-2 degrees when I moved the laser in the eyepiece socket. Weird.
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Old 04-04-2019, 05:24 AM
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Ukastronomer (Jeremy)
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What you have failed to consider is the fact that you have no idea if any other astronomers locally to you may be imaging and could have spent hours doing so only to have the work ruined by a laser
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Old 04-04-2019, 07:08 AM
glend (Glen)
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Having had a laser inadvertently and momentarily pointed into my scope while I was observing, my opinion is they have no place in astronomy. People waving lasers around are simply dangerous, regardless of the present power restrictions in parts of Australia. I have heard all the arguments people put forward for them as educational tools but it comes down to the Duty of Care shown by the holder of the laser. Frankly, people cannot be trusted.
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Old 04-04-2019, 03:47 PM
Wavytone (Nick)
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Quote:
Originally Posted by Ukastronomer View Post
What you have failed to consider is the fact that you have no idea if any other astronomers locally to you may be imaging and could have spent hours doing so only to have the work ruined by a laser
Oh really ? No worse than a plane flying over or having the ISS pass overhead. They’d only lose one or two subs.

Having had one a while back lasers don’t make great finders for several reasons, plus the safety issue.

The one application where imho they could help - via a polar axis scope - is to show where the polar axis is pointing on the sky.
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Old 04-04-2019, 07:41 PM
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barx1963 (Malcolm)
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I used one for a while on my 12" dob. Only used it to get to a bright star before doing a star hop. I was living in a country town with no other astronomers nearby or air traffic apart from the very occasional Police or Ambulance helicopter.
Works OK but a good red dot finder does just as good a job and is far less affected by the cold and cheaper! Once temp drops below about 5deg C, the laser needed heater straps to keep operating.

Malcolm
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Old 05-04-2019, 02:12 PM
N1 (Mirko)
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Originally Posted by barx1963 View Post
I used one for a while on my 12" dob. Only used it to get to a bright star before doing a star hop. I was living in a country town with no other astronomers nearby or air traffic apart from the very occasional Police or Ambulance helicopter.
Works OK but a good red dot finder does just as good a job and is far less affected by the cold and cheaper! Once temp drops below about 5deg C, the laser needed heater straps to keep operating.

Malcolm

+100 on the RDF!
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Old 06-04-2019, 01:38 AM
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tempestwizz (Brian)
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I use my laser pointer as a rough pointer, then either a rdf or finder scope to home in. The power button activates only momentarily for long enough to get the Dob turned in the general direction. Others in my group have used them during viewing sessions, and there have never been any complaints. Not even from imagers including myself.
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Old 09-04-2019, 10:09 AM
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sil (Steve)
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Quote:
Originally Posted by glend View Post
Having had a laser inadvertently and momentarily pointed into my scope while I was observing, my opinion is they have no place in astronomy. People waving lasers around are simply dangerous, regardless of the present power restrictions in parts of Australia. I have heard all the arguments people put forward for them as educational tools but it comes down to the Duty of Care shown by the holder of the laser. Frankly, people cannot be trusted.
I totally agree.

I use mine still as an essential tool in alignment for imaging. Am always alone, it never leaves my possesion nor do i grab it to point out out things when others appear. its only used for one purpose and as brief as possible.

No it may not be technically legal for me and yes i am fully aware of how dangerous they can be and accidents can happen for well meaning folks. Will i stop? nope. I think people themeslves should just be banned. they are the weak link thast results in tragedy. I still agree there is no place for them really at all.
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Old 09-04-2019, 08:53 PM
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ANYTHING that selfishly ruins another persons pleasure is just that, an act of selfishness

"they may only lose one or two subs"

Sorry, selfish attitude
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Old 17-04-2019, 02:11 AM
Renato1 (Renato)
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Lasers do have one neat use in astronomy. When showing one or more people with binoculars the brighter deep sky objects, just point to any of the Orion Nebula, Eta Carina, Omega Centauri, Andromeda galaxy etc and tell them to follow the beam with their binoculars. They all say "Wow" when they locate the objects, especially when you've previously shown them those objects in a telescope.

Only problem is that at the end of the night, they are often more impressed with the laser light itself, than with the objects.
Regards,
Renato
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  #11  
Old 17-04-2019, 07:58 AM
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Quote:
Originally Posted by Ukastronomer View Post
ANYTHING that selfishly ruins another persons pleasure is just that, an act of selfishness

"they may only lose one or two subs"

Sorry, selfish attitude
"Nobody is allowed to use a laser pointer, because I'm imaging here" also selfish.

The only real solutions are based on mutual respect, and painting someone into the naughty corner right from the outset is not a good start.
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Old 22-04-2019, 02:48 PM
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Originally Posted by Steffen View Post
"Nobody is allowed to use a laser pointer, because I'm imaging here" – also selfish.

The only real solutions are based on mutual respect, and painting someone into the naughty corner right from the outset is not a good start.

It's apparently ok for their computers to flood you with light though.
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