Laser pointers

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duncanat7
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Laser pointers

Post by duncanat7 »

Can anyone advise on best value laser pointer for use in pointing out featues of interest in night sky? Any advice on what to get and where from? Ideally smaller rather than larger for ease of transport. Max budget £100, but happy to spend a lot less!

Very many thanks for suggestions - will think of you when checking out dark Lanzarote sky!
Brian
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Re: Laser pointers

Post by Brian »

Hi Duncan, Welcome!

Don't use them myself, some here do I think but this one seems popular:

http://www.ebay.co.uk/itm/1mw-Green-Las ... 45fa95f7b1

At your own risk :)

ATB,
Brian
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Eclipse
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Re: Laser pointers

Post by Eclipse »

You will need more than 1 mW for pointing out astronomical objects. The beam pointing up into the sky is only visible because dust particles get illuminated and reflect light - this is different to illuminating an object in a lecture theatre, where you will get a bright point of light where the beam strikes a solid object, and 1mW is fine for that.
A member of my group has a 5mW green laser, and the beam from that is very dim in our light polluted skies. Should anyone wish to point out astronomical objects to the assembled punters, it is always my 50mW beast that is called into play. In winter keep it warm in your pocket - when it is mounted on a scope I keep the business end warm with the wife´s hairdryer - I have a 12V model for when I am in the field. Lithium batteries are also highly recommended for a bright beam and long battery life.
Last edited by Eclipse on Sun Aug 19, 2012 1:41 am, edited 1 time in total.
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brian livesey
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Re: Laser pointers

Post by brian livesey »

I have several laser-pens and the beams vary in strength regardless of the marked mWs. I have a 1 mW pen that gives a beam that's perfectly suitable for pointing out sky objects.
Many laser pens are temperature-sensitive and don't work as a 'scope finder unless kept warm in some way.
If we want to home in on a target on a cold evening/morning, we can keep the laser-pen warm in a pocket. Then, remove the eyepiece and shine the laser down the focuser. This will send the beam into the sky, so that we can slew the 'scope onto the target object that we wish to observe.
The laser doesn't work for this purpose if we leave the eyepiece in the focuser and try to shine the laser down through the eyepiece.
brian
MikeMS
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Re: Laser pointers

Post by MikeMS »

Hello All.

I have owned a 1 mw and 2 X 5 mw. THe latter seem a lot better. In reading Brian's comments of shining the laser down the focuser, I have shone it down the finderscope and it does appear in the sky.

And the comments about the cold are very true.

The last one I purchased on ebay for a few £, posted from Hong Kong and pay pal thought is was a false ad, so refunded my money but the laser pen still arrived and works. I have also had replies from the seller. I am tempted by the 10 X laser pens for £30 from Hong Kong on Ebay.

Regards,

Mike MS.
brian livesey
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Re: Laser pointers

Post by brian livesey »

A problem I find with more powerful laser pens ( like my 50mW one ) is overkill. The stronger beam washes out the target object. The best laser pen in my collection produces a much fainter, thinner, beam that doesn't detract from the target and makes it easier to lock on to it.
I like to use one of my laser pens to entertain my granddaughter's cat. The little feline would chase the green spot all day if she could. It's amusing to see the expression of intense, predatory, concentration on the cat's face, going through the motions of her bigger cousins, when she prepares to pounce. Glad I'm not a mouse. :lol:
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Eclipse
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Re: Laser pointers

Post by Eclipse »

brian livesey wrote:A problem I find with more powerful laser pens ( like my 50mW one ) is overkill. The stronger beam washes out the target object.
Agree to a large extent - which is why my 300mW is used for other things. I find 50mW perfect for mounting on the scope.
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astroeddie
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Re: Laser pointers

Post by astroeddie »

Guys,

Where can I buy one of these stronger laser pointers.
Would like one to take to sea. To show the crew objects when they are out with me.

Eddie
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Eclipse
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Re: Laser pointers

Post by Eclipse »

astroeddie wrote:Guys,

Where can I buy one of these stronger laser pointers.
Would like one to take to sea. To show the crew objects when they are out with me.

Eddie
Do a Google. I think my most powerful laser was on eBay.
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David Frydman
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Re: Laser pointers

Post by David Frydman »

. Today's Sunday express has a front-page article about these, in particular about high-powered laser pointers.
I don't actually have the newspaper but it was reviewed last night and the article can be read online.
it mentions astronomers also.
There is very widespread abuse of these.

It calls for custodial sentences for anyone in possession of these without proper reason.

I mentioned this several years ago and that was my opinion then and it is still my opinion now,
despite any protests by astronomers.

Regards David
groberts
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Re: Laser pointers

Post by groberts »

I am also interested in getting a laser pointer but am unclear from the answers which is the way to go.

1. Taking on board the issue of misuse, what is therefore the best pointer for astronomical use? I presume the higher the mW the more powerful the light, however, some here seem to suggest that a 1mW light will do the job, is this not too weak?

2. I am also confused on what is legally OK - I have seen 1mW in some places and 5mW elsewhere - which is it?

3. Finally, do I understand Brian Livesey's point correctly - are you saying you can shine a pointer through the eyepiece to help locate something for viewing?
brian livesey
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Re: Laser pointers

Post by brian livesey »

Apologies for the late response. The eyepiece has to be removed first. The best laser pens are supposed to be the ORION brand from America. They don't seem to be temperature sensitive, but they are/were quite expensive.
brian
groberts
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Re: Laser pointers

Post by groberts »

Thanks Brian :D Would this be worth getting too?

http://www.scopesnskies.com/prod/laser/ ... AC666.html

+ any other comments on points (1) & (2) ?
M54
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Re: Laser pointers

Post by M54 »

If you can track down a 10mW I think they are the best all round.
Had a 5mW and I gave it away it simply was too dim. Equally I used it often at home and there was light pollution.
Had a 50mW but that was overkill, except for one situation where it exceeded.

Legality: Well that seems to be one of those areas where when they came out nothing was done (bit like the CB radio). The "rulings" now fall under H&S. They specified that for presentations inside 1mW was the limit - in case you shone it at the audience. 5mW is often quoted but that is the US limit, and even that is open to loopholes to get around. After that it is an offence if you aim one at people deliberately.

I got a 10mW eventually and I will say it is a nice power, would like a second but the people I got it from (GY3) seem to no longer advertise them.

There is a question about power rating.
Using mine as an example, 10 is a nice munber.
You can get a 10mW GLP that has an IR filter, in which case I believe that the outpower is supposed to be 10mW of green light.
You can also get a 10mW without an IR filter fitted, in which case part of your 10mW coming out is IR not green. So these appear a bit dimmer then the others.
Eclipse
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Re: Laser pointers

Post by Eclipse »

If a laser is mounted as a piece of scientific equipment - ie not hand held - then different rules apply. At a certain establishment in Berkshire they use lasers to initiate nuclear fusion - they are a bit more powerful than 1 mW!! Mounted on your telescope may appear to be covered by this proviso.
Anyway I have stopped using laser pointers now that I have moved to solar astronomy.
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