I have an 8" dob and I have a laser pointer and I have read that some people use their laser pointer as a 'guide scope' that is they mount the laser pointer to the scope and it 'points' to what they are looking at.
However, I cannot get a clear picture in my head how the laser actually 'points' at anything - have I missed something V basic?
Pop your wide field eyepiece in (26mm or similar) and focus on the stars. When there are no planes in the sky (!!), place your green laser on the tube, holding it beside the focusser base, pointing at the sky (this works on GSO solid tubes fairly well), touch the button and see if enough light bypasses the end of the tube (that is, it doesn't all hit the rim and scatter brightly around!). Then you'll have your usual beam into the sky. Look into the eyepiece and see if you observe the end of the laser pointer in the field of view - it's a neat view. Depending how your tube and focusser are set up, you might be lucky. If not, then a bit of blu-tack under the appropriate part of the laser pointer can be used to redirect the beam until it is in your field of view.
That sorted, you then hold your laser pointer in place, press the button, then move the scope, observing the sky until the end of the beam is where you believe the object you want to observe should be. Laser off, look into the eyepiece and you should have the object in the field of view.
That's the way I do it. Once I am on the target, I pop the laser back into my upper pocket to keep it nice and warm for the next use.
Andrew
Couple of points, is your laser a green laser? If it is a plain red one it is no use. Secondly if it is green be aware that they are illegal in most states unless under 1MW, not sure about Canberra.
You can buy lasers with a mounting bracket that replaces your guide scope or drill a couple of holes to mount it to the tube see here http://www.myastroshop.com.au/produc...p?id=MAS-017H2
Just be aware of the legal situation, I live in the bush so there is almost no air traffic, but wouldn't use one in the city!
Malcolm, my laser is red and I'm colourblind so I don't really see it well anyway
Eric, thanx for the 'walkthrough', I never really thought of just trying it (probably a good job seeing as my laser is red!!). I guess I'll just wait for my red dot finder that the kids don't know they're buying me for Christmas HAHAHA
Simply get a green laser pointer, and a laser pointer finderscope bracket, and attach it.
It turns it into a 1x finder that you don't have to crane your neck to view through. I tried it for a while on a 12" dob and it worked a treat. I took it off, however, as I live *very* close to Moorabbin Airport and ... well.
I have a green laser setup in my observatory at home and you are apparently only 7kms from me, so I am sure we can work out a practical time that suits both of us in which you could take a visit.
I have sought permission from the ACT Firearms Registry Sgt to use the green laser for astro use and am also apart of a registered astro society club (CAS).
Vaztr, if you are still thinking about a pointer it is not that expensive or difficult to attach one to your scope. I wish I had done it earlier.
I picked up a $10, 1mW green laser pointer from ebay to experiment with. Suzy had success with the same item, so I was confident that the supplier and product would be good. The beam is visible at night but not so bright that it will gain the attention of your neighbours.
To make BAS public viewing sessions easier I have zip tied a piece of PVC pipe to the stalk of the finder scope. Small threaded bolts have been positioned at each end of the tube to allow adjustment of the pointer. Another was positioned over the momentary switch in order to turn it on for as long as necessary. Some more work will need to be done to position the tube a little better but the whole setup works. It can now be used to point the scope and let people know exactly where the object they see through the eyepiece is in the sky.
The second photo is a 30 second exposure to allow the beam to be seen in the image.
I am about to purchase one, but I just wanted to check whether the concensus is that 1 mW is sufficient, or do you need a bit more power?
Cheers
John
As delivered, the 1mW green laser pointer is just bright enough for a beam to be visible by yourself and those who are standing next to you. A person 5m away will not really notice the beam unless they know you are using it.
I purchased mine from the same place that Suzy did:
You don't have to pay via ebay. I paid directly into Nikkie's bank account.
If you don't mind reducing the expected 5000 hour life of the diode you can carefully pull the laser apart and tweak the pot to increase the output.
As the cost is so low, I experimented with this and the beam is noticeably brighter. I have ordered a small piece of IR filtering glass to eliminate unwanted IR wavelengths of light. Just be aware that you do run the risk of damaging the laser module when you pull it apart. The photo in my last post is a 30 second exposure so don't use that as a guide to brightness.
I have since ordered a 40mw green laser module with another piece of IR filtering glass in order to build my own pointer. It will fit into the same pen housing but I will order a new laser host to keep things looking neat. It is quite legal to order the parts and build your own but you will have to check the laws in your state regarding the legalities of using your higher power laser pointers.
Last edited by Shark Bait; 06-12-2012 at 11:00 AM.
I use a 50mw and its probably over kill however compared to my mates 5mw his you need to strain to see where as mine is like a deathstar.
Being so bright helps not so astronomy minded people easily see it and see what you are pointing at, you know those kind of people who go camping with flood lights and shine head torches in your face while you try and point out constellations.
I saw an American using one of those 1000mw ones and in the photo it was very intense but I think NASA might have something to say about if you were to shine it at the ISS "Astronaut blinded by land based laser"
I have the same 1mw one and it is plenty bright enough for my own use and the kids see it easily when standing a couple of metres away from the scope. Maybe mine is adjusted a bit brighter by default? But for $10each you can buy a couple and ramp them up to max I guess and not be too worried about the lifespan.
Stu, I love what you've done with that pointer- I want to do that with mine!
I found my 1mw bright enough even with neighbours lights on, street lights and the full moon. It's not kapowww bright, but I didn't need to struggle at all to see the beam. Shelley was here with me trying it out too and she had no problem, in fact she ended up buying one the next day. We had just as much fun with the disco lights, hmmm Xmas with it will be awesome!
Steve, 50mw really?! I'm guessing you're used to such brightness and perhaps that's why the 5mw appears very dim to you- me, I know no better. I live very close to an airport- they'll find me easily if started throwing one of those around. It's like a business card saying, I'm doing very bad things and here is where you can find me.
Would everyone who loves their 1mW laser just keep quiet about it, else the powers-that-be may limit us all to that low output!
(It's a bit like people who drive a 1.4L Barina saying thay can't understand why anyone would want a 5.0L V8 and suggesting anything over 2.0L should be banned .... and I've actually heard them with my own ears).
(Edit: On re-reading this, I realised it may have come across a bit gruff. That was not my intention. Everyone is entitled to their opinion of course and who's to say which is right? Unless it's me. Because I'm always right. )
You lot probably missed seeing a 50W green laser at the Macquarie Uni open night a couple of years back. Talk about bright!
They need permission to run it outside and pointed at the zenith. All air traffic in Sydney was diverted away from North Ryde for several hours.
I have one of the 20mW ones with the SCT mount. A different brand but it looks the same. The laser cell is so badly off-centre that I can't align it. I'm tempted to pull it apart and see if it can be fixed - if I can ever figure out how to get it apart.
I got my 30mW pen style one from MyAstroshop, and rings to mount it.
I have one of the 20mW ones with the SCT mount. A different brand but it looks the same. The laser cell is so badly off-centre that I can't align it. I'm tempted to pull it apart and see if it can be fixed - if I can ever figure out how to get it apart.
Getting them apart without damaging the laser module is the trick. As it is that far out, it might be possible to salvage the module and fit it to a new host.
Last edited by Shark Bait; 07-12-2012 at 09:53 AM.
I have a few different powers. 50 80 and 100 MW. I purchased some low cost red lasers on the E-Bay and then purchase the laser modules the same way. They come into Australia fine as they are a spare part. I them pulled the red lasers apart and fitted them with the Green modules. Very Simple and Very Very cheap way to do it. The Astro shops are charging a fortune for the same thing... Works great for me.. When I am out in a dark place setup and alignment is made very simple with them..
and I'm colourblind so I don't really see it well anyway
I'm guessing you're used to such brightness and perhaps that's why the 5mw appears very dim to you- me, I know no better.
I live very close to an airport- they'll find me easily if started throwing one of those around. It's like a business card saying, I'm doing very bad things and here is where you can find me.
