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Collimation of a laser collimator

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I read on the web that using a laser collimator was useless unless it was in perfect collimation. Sadly as is so often the case the advice fell short of prescribing what one is supposed to do to get that done :confused: . So can one of the experts that so frequently explain stuff on this forum so it is easy to understand, please step forward to reveal to us less experienced folk how this done please? :smiley:

Thanks, N.

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John

John

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This link might help:

http://www.stark-lab.../llcc/llcc.html

On my laser collimator there are 3 hex screws spaced around the body of the collimator which adjust the angle of the laser unit inside a bit. The trick is to get the beam to stay on one spot, say projected on a wall, at least 10 feet away, as you rotate the collimator around 360 degrees.

This method only works if you have a symmetrical laser collimator like the one pictured in the web link.

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JamesM

JamesM

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I have the Hotech brand that also have the facility to calibrate via three small grub screws. What I do when fine tuning the laser is to use its 2" adapter, which I connect to a similar sized hole in a piece of MDF which can be secure perpendicular to say a kitchen work top. I insert the 1.25" laser barrel into this 2" adapter and this permits me to turn it 360 degrees to test if the projected laser dot moves from what should be a centered fixed position. I have even heard of people using a lathe (metal or wood turning) in which they insert the collimator into that in order to facilitate the turning action. Now the reason my method differs from the above suggestions is that I only configure the laser against a single axis point, namely the part of the collimator that will be on contact with the scope when you are collimating. Using two points of axis introduced an additional reference point from which to align the laser and I'm not entirely convinced that this method is the most efficient - perhaps someone with someone reading this who has some engineering experience can advise which is the preferred method. :smiley:

I'm sure that most of the laser collimators available today can be fettled to maintain accuracy and are certainly useful when collimating scopes with long focal lengths, though there are many members who don't use them and attest to being able to maintain their scopes in good order using the more traditional approach proving that lasers are convenient but not essential pieces of kit.

James

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Steve Ward

Steve Ward

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I shimmed mine with thin packing tape , 1 layer at a time until I got a nice smooth snug fit in the EP holder of my ED80 and used the scope to project the dot onto the wall about 12 ' away.

I'm guessing that more astronomers have telescopes to use than lathes here . . . :p

Then rotated in the EP holder and adjusted as required.

You may have to dig out some black silicon sealant from the adjusting screw holes that the manufacturers "kindly" apply to make things simple . . .

Steve.

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Daniel-K

Daniel-K

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GO CHESHIRE! i hate laser's just cant get along with with so i opted for a cheshire never had an issue,untill i bought a fast newt and had to buy a auto coliimator, but you 4inch reflector would be far easier and quicker with a cheshire

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ollypenrice

ollypenrice

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Blimey, that's even more agricultural than mine. I at least cut some wooden V blocks for mine :)

James

Indeed, but the nails will be totally accurate. I like this kind of technology which, in a way, is rather elegant. The plank into which they are banged should ideally have three points of contact with whatever it is standing on so that there can be no rocking. I heard of the nails trick a few years ago and have used it ever since. A top tip!

Olly

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BinocularSky

BinocularSky

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The plank into which they are banged should ideally have three points of contact with whatever it is standing on so that there can be no rocking.
If you do like my Dad taught me to do with my oilstone boxes, if those 3 points of contact are nail points protruding by a fraction of a mm (panel pins, nipped of with the pincers does the trick for me), the plank won't slip on that wooden table it's on either.

That said, been using a sight tube and Cheshire for so long that the laser collimator I acquired seemed so time-consuming by comparison that I flogged it....

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Steve Ward

Steve Ward

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You've the same laser as me , the adjustment screws are "buried" under the 3 dollops of silicon that seal the three holes just behind the brightness control.

One of the holes is probably covered by the laser warning sticker.

Test it out first as it may not need collimating.

If it does you'll have to dig out the silicon to access the allen heads.

Steve.

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JamesM

JamesM

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So I'm gong to take the approach set out herein by Steve Ward and I'll pack out the diameter of the collimator to make sure the fit is good and tight.

N.

You might want to think about using one of these modestly prices self centering eyepiece adaptors which looks similar to one by Orion. Its tightening mechanism ensures that the eyepiece (...or in your case the collimator) is kept dead centre.

James

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tingting44

tingting44

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You might want to think about using one of these modestly prices self centering eyepiece adaptors which looks similar to one by Orion. Its tightening mechanism ensures that the eyepiece (...or in your case the collimator) is kept dead centre.

James

i have to say this centering EP looks rather appealing!!! :)

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SplintUK

SplintUK

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You might want to think about using one of these modestly prices self centering eyepiece adaptors which looks similar to one by Orion. Its tightening mechanism ensures that the eyepiece (...or in your case the collimator) is kept dead centre.

James

I use an Antares self centring adapter with my Nex Gen laser (+1 for the adjustment screws being under the black sealant - 1 is behind the laser warning sticker - dig em out with the point of a corkscrew) and it works just fine.

In terms of the collimator holder for adjustment - I've been using my dob with the laser mounted back to front so it points out of the focuser towards the wall, then put a post-it note on the wall so I can mark a target etc. if you're on a an eq mount, I guess it would work the same too, mount up the ota, stick the laser in backwards, twist ota to point laser at wall.

I'm fairly sure we must all have a telescope with a focuser on it knocking about the place :-)

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JamesF

JamesF

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You might want to think about using one of these modestly prices self centering eyepiece adaptors which looks similar to one by Orion. Its tightening mechanism ensures that the eyepiece (...or in your case the collimator) is kept dead centre.

But how do you get your self-centering adaptor centered? :)

James

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JamesM

JamesM

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But how do you get your self-centering adaptor centered? :)

I don't think the issue is whether the collimator is 'centered', is really about whether it is aligned within the axis of the focuser of which the self centering eyepiece holder would most certainly help. Most mirrors have a circle marking it's centre but unless the scope's tube is significant in length, the effects of any miniscule off centre alignment is in my view negligible. So is the 'fit' of the suggested holder more snug than the collimator, I have no idea but it will present the collimator to the focuser in the correct alignment, well in my view it will certainly help. It's a suggestion that I know others use and nothing more. ;)

James

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Wow, I know it's Christmas, but this level of information is astounding :laugh: . Give yourselves (yet) another mince pie :tongue: . I'm going to set-up one of the jigs detailed at the start and see if the collimation is out. If it is then I've got a few options as proffered by the end experts on this forum (secretly I hope it's set just fine :Envy: ) and I'll update you on the outcome. Doing this on Christmas eve could mean I need a miracle to keep my marriage together, so give it a few days eh! :grin:

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Quick update; discovered the 'play' on the rack-and-pinion focuser is so bad that collimation to fine degree could be a waste of time (but I hope not). Strapped tape around the Collimator to get a really good fit in the focus tube. Did one last test to see if I could get the same results with the laser after setting up manually (I didn't). So I'll continue with the jigs and test the laser collimation.

I'm beginning to suspect that this is a bit of a waste of time unless one has top notch kit. Will update you soon.

N.

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Happy to report that the Next Generation laser Collimator was in perfect collation (I built the jigs and created a calibration chart with a compass). So that's one variable ruled out. But I'm still getting strange results. The mark one eye-ball gets the mirrors lined up nicely. The laser is then used to fine tune the alignment. Then a quick retest with said mark one eye ball shows a newtonion out of collimation. Does anyone else get these problems? If so then what do you do?? :embarrassed:

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