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Tony Legge
Joined: 13 Oct 2006
Posts: 9
Location: Cambridge, England
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 Posted: Sat May 10, 2008 11:29 am Post subject: GREEN LASER POINTERS |
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| There have been reports that green lasers have been used to interfere with aircraft in both Britain and Australia. I use an 8mw green laser pointer on my Dobson, and it works very well. But I am under the stack for Stansted airport in England (most of England now seems to be under an arrivals flightpath!). Is using my laser as a starfinder going to be a problem? I would be glad to see some information. |
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G4LED
Joined: 24 Nov 2006
Posts: 26
Location: Holmfirth UK
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| Posted: Sat Jun 28, 2008 9:53 am Post subject: GREEN LASER POINTERS |
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Green Laser Pointers
Tony
With the recent court case concerning laser pointers and aircraft I think you are now batting on dangerous and easily pinpointed ground. I suggest that these pointers be used solely handheld to assist guests in finding objects in the sky. Finger pointing as you know is hopeless. It will mean you are in charge of the beam constantly rather than it waving about as the scope is moved.
I first had a demo of a laser at the Galloway Astronomy Centre and the idea certainly appealed to me then, for demo purposes. It was a green one, of maybe 5mW in quite a dark and contrasty sky.
For fixed OTA use I had my doubts. So with my Intelliscope Dob I immediately settled on the red dot finder by AE (Astro Engineering) fixed by it's base plate with Evo-Stik contact adhesive almost at the end of the OTA. The self-adhesive pads supplied come loose with dew conditions! Mostly I just approximately sight through the small circular 'window' from roughly the trunnion axis. Switching on the actual dot only for a precise star fix. The window view is enough to align the spotter scope and then work from the star field.
Snag is the device uses button cells which I greatly dislike. I would have liked one with AA batteries but was unable to find a suitable candidate. I did try the Telrad but it was too bulky and easily knocked in the showroom, never mind in the dark on a windy night!
But which laser to buy and what power? Preferably with an AA battery box, to be compatible with all else around this place.
g4led
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"Holme Valley Weather" Davis Vantage Pro+ station; XT10 Orion Intelliscope(frontspiece) |
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Tony Legge
Joined: 13 Oct 2006
Posts: 9
Location: Cambridge, England
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| Posted: Mon Jun 30, 2008 5:06 pm Post subject: |
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Thanks for that. I will take great care. I have never seen a red dot pointer in use; how does it work?
Tony |
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G4LED
Joined: 24 Nov 2006
Posts: 26
Location: Holmfirth UK
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| Posted: Sun Jul 06, 2008 7:11 pm Post subject: Red Dot Reflex LED Finder |
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Red Dot Reflex LED Finder
Tony
Mine is the device manufactured by Astro Engineering. Their full name is BC & F Astro Engineering. Details of their device, with a picture (can be enlarged) are to be found at:
http://www.astro-engineering.com
This small finder is simply a plain circular translucent plastic disc mounted in a black plastic moulded arrangement. It is about 27mm diameter, a little larger than our English 2p coin.
Two small threaded adjuster knobs enable precise aligninment on the OTA and as I mentioned, mine is permanently glued on. One's cheek is placed near the OTA lower down near the middle and you look distantly through the disc aperture at the night sky. This method accommodates a range of viewing angles.
By rolling on a similar style knob (to the right rear) a tiny LED red dot can be seen in the disc, projected from the device's body and reflected towards the viewer's eye. Moving the 'scope shifts the dot around and it can be easily superimposed onto a particular star, for example Polaris. Look into the main eyepiece and there it is.
The much larger Telrad I tried had concentric circles which , for me, seemed a logical idea. However they cluttered the scene somewhat. They would be an advantage where a starfield was being examined perhaps and comparative angular separation was needed.
The red dot in the Astro is quite visible on the minimum, initial setting of the knob; by rotation the knob acts acts as a rheostat and the brightness can be increased as desired. The minimum setting I find entirely adequate and greatly increases battery life. I confess these I have never examined but they are the small, button types, installed under the front window.
Thoroughly recommended and about £22 back in November 2006
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"Holme Valley Weather" Davis Vantage Pro+ station; XT10 Orion Intelliscope(frontspiece) |
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