Laser Collimators

[orions-knight]

You either love 'em or hate 'em. At this moment I hate mine.

Its a crappy design baader planetarium brand that is not easy to collimate or even replace the batteries taking button cell rather than "conventional type" batteries.

So I am now wondering what type of batteries the more expensive and professional laser collimators take.

So if at all possible, would all you peers that use laser collimators be able to enlighten me and other members of the forum that may wish to purchase a laser collimator in the future of such trivial pitfalls.

Many thanks for your time and understanding

Orions-Knight

[samtheeagle]

Well I can only speak of my very brief experience of a second hand Antares laser collimator I recently picked up. Only used it once but it was a dream. Did a quick check of it's own collimation using a "V" block, and it seemed spot on, and then did the honours on the Newt.

Easy to get the the battery (CR2032), easy and chunky on / off switch. Does the job, no hassles.

[John]

I use a Revelation one (same as the Antares I think). It did need colimating when it 1st arrived but, after some fiddling and the old "V" block collimation samtheeagle mentions it's pretty much spot on now. I still use a star test to do the final adjustments though.

I'm going to try barlowed laser collimation when I can get hold of a cheap barlow lens - it's supposed to be more accurate from the reading I have done on it.

[Doc]

I use a Hotech laser collimator and tweak with a star test. But recently have been mucking about with a videocam to get a much more accurate collimation.

[TopHouse]

Another vote for Antares, had to collimate mine though but collimated it in the scope using the orion precision self centering eyepiece holder. Bear in mind there are two Antares ones, mine is the black one with the target, there's a grey one too with a large shoulder on it.

This is mine

Antares Newtonian Laser Collimator

this is the other Antares one

Antares 1.25" deluxe laser collimator for astro telescopes

[samtheeagle]

Thanks for the clarification TopHouse. Mine is the smaller black style Antares.

[orions-knight]

Both lasers look far more substantial and 'V Block' friendly than the one I have. So do these use button cell batteries or do they use easy to purchase off the shelf batteries such as 'AAA'.

I would post a link or photo of mine but its the strangely shaped one that has a sort of ribbing around the laser holder with a sort of a handle on the underneath which prevents it from being 'V Block' friendly. These are the two main issues I have with this laser. Why I chose this one is beyond me, probably aesthetics and cost. Not practicality and quality. Think its time to invest in something a 'bit more' professional.

Many Thanks

OK

[samtheeagle]

The Antares one I use takes CR2032 batteries.

[TopHouse]

What puzzles me is your bias towards 'normal' batteries as the batteries should last a hell of a long time.

If you want my honest advice after seeing the options, you only really have two choices.

1) Hotech collimater which has inbuilt self centering and is self collimatable but will cost around £100

2) Antares one AND buy an Orion Precision self centering holder, total cost for the pair would come in at under £100 Antares one is also self collimatable.

I have option 2 and personally I think it's the best option, the reason being, the self centerer is a great piece of kit, replaces your standard scope eyepiece holder and you use it with all your 1.25 eyepieces. 100% better than the '2 screws' EP holding method.

Having played with a LOT of lasers though, I will say that the actual lasers used in collimaters are of really crappy quality, if you shine one onto your hand you see a 'fuzzy' red dot of approx 5mm, not so precise, some laser diodes come with a tiny focusable lens that can be adjusted (normally factory adjusted) with a paper clip (ring with 2 holes), if they used a focussed diode in these laser collimaters you would get a sharp edged, well defined dot of a similar size to the lead in a pencil. The diodes used in these collimaters is frankly no better than the cheap laser pointers you can buy in various holiday destinations for £2.50 methinks there's a lot of money to be made in producing astronomy gadgets!

[John]

The diodes used in these collimaters is frankly no better than the cheap laser pointers you can buy in various holiday destinations for £2.50 methinks there's a lot of money to be made in producing astronomy gadgets!

I took one apart once and that is exactly what was inside it !. I guess the body needs to be machined fairly accurately and that is what you are paying for.

My current one is the "other Antares one" that Tophouse posted links to except it is black and is branded Revelation.

The problem with the Baader Laser Collimator is that it's body is not symmetrical so you can't really use the "V" block method to collimate it - the instructions with them actually suggest that you return the device to the factory for collimation.

The reason I'm interested in the barlowed laser method is that it it is supposed to remove the inaccuracy that slop in the focusser can create. Here is a link describing the method if anyone is interested:

http://www.smartavtweaks.com/RVBL.html

[Astro_Baby]

I have had a cheap generic one (twice) these are the same as the SKy-Watcher ones. Both were hopeless and both broke quite quickly (which was lucky as I could get my money back). The battery compartment/on/off switch fell off both of them.

I had a Baader one which was not much cop either. Never owned it long enough to find out what batteries it has. Sent it back from whence it came.

FInally I had a Hotech very early on - Steve at FLO was kind enough top provide me with a very early sample. In the world of laser collimators its probably the best (though I havent tried the Howie Glatter ones).

The Hotech also uses a strange battery size - but its of a kind that most photo shops would have even if Asda dont.

The Hotech was much more than its self centreing system though. The whole quality of the product was head and shoulders above anything else I have personally seen.

Its as solid a laser as you could ever hope to find I think.

Do I use one ? No - I prefer a Cheshire because its simpler, needs no batteries at all and even the best laser collimator will require you to use a sight tube to set up the secondary mirror.

That takes me on to one of the reasons I distrust lasers. When you adjusting rthe secondary tilt with a laser in order to get the laser onto the primary centre spot its all too easy for the secondary to start rotating slighltly. You get perfect alignment with the laser and then find that the secondary has developed a rotation error.

This is easy to spot when your using a sight tube but impossible with a laser unless you are constantly swapping the laser for the sight tube.

Now IF the secondary adjusters were done better on scopes (and I have seen some big dobs from Star Splitter and Obsesion that get over this) then a laser becomes much more useful.

I'd only acquire a laser these days if I had a long tube scope and use it purely for aligning the primary just for ease of use. If I bought - I'd get the Hotech. Its just a well made bit of kit thats been thought through properly.

[John]

....When you adjusting rthe secondary tilt with a laser in order to get the laser onto the primary centre spot its all too easy for the secondary to start rotating slighltly. You get perfect alignment with the laser and then find that the secondary has developed a rotation error.

This is easy to spot when your using a sight tube but impossible with a laser unless you are constantly swapping the laser for the sight tube....

An issue that I have run into with my Orion Optics newtonian is that the tips of the secondary adjustment screws have carved out little pits in the top of the soft metal boss that holds the secondary mirror. So when you loosen the screws to adjust the rotation of the secondary, as soon as you tighten them a little, they settle back into the pits putting things back where they were .

I've got round this, removing the secondary holder from the scope and adding a 40mm diameter hardened steel washer to the top of the boss so that the tips of the collimation screws push against that. No more pits and I now have full control of the rotation of the secondary

[Astro_Baby]

John,

Its a mod I keep meaning to do but never seem to get round to

[TopHouse]

I'd only acquire a laser these days if I had a long tube scope and use it purely for aligning the primary just for ease of use.

And aligning that moonlight that you haven't aligned

[Jason D]

I've got round this, removing the secondary holder from the scope and adding a 40mm diameter hardened steel washer to the top of the boss so that the tips of the collimation screws push against that. No more pits and I now have full control of the rotation of the secondary

Using a hardened steel washer is a common solution to the problem mentioned. However, I came up with an alternative solution of using two stacked perforated discs cut from a plastic container. The two discs make it easier to rotate the secondary during adjustment. More importantly, the plastic elasticity works like micro-springs. It allows to slightly screw-in one adjustment-screw without the need to unscrew the other two. I collimate my scope with an autocollimator which requires precise secondary mirror adjustments.

Jason

[orions-knight]

Some interesting points and useful techniques mentioned when using a laser to collimate. However, my biggest gripe was the batteries. So I decided to go to Maplins today to see how much I could purchase them for. Couldn't get the originals but 3 replacement batteries required for £2.19 each. Nigh on £6.60. 'Ouch'.

Guess what ? They sell a Rolson Tools torch with 3 batteries in it that would do the job. How much ? £1.99. :)

I bought 2.

Use the batteries for my laser and throw away the torch. Don't make sense at all.

I am on a mission now to see if I can locate cheap batteries to replace the ones in the torch. A jewellers wanted £5.95 for "1". Yep, £5.99 for '1'. No thanks.

Next I went to a top gadget shop and nearly purchased 10 @ £0.95 each. Not bad really, but then thought that if I wanted to replace the batteries in the torch, was it really worth it as it would now cost me £2.85. Might as well buy a new torch for £1.99. So what a waste of a lovely aluminium carcass of a torch. Talk about a throw away society indeed.

Yes, my laser now works, but what a waste of time and energy all for the sake of a couple of button cell batteries. I hate button cell batteries. They're just so hard and expensive to replace.

Sorry. :)

Gripe over.

OK

[orions-knight]

Took me ages to write my gripe and missed Jason D's 'excellent' Idea. Nice one.

I am using the steel washer method atm and like the 2 plastic washer method. Think I might give that a go myself one day. Nice one Jason.

OK

[Astro_Baby]

:pYour right tophouse but I decided not to bother after a lengthy discussion with some one who had done it who said he considered it mot really worth the effort. I certainly dont want to stup up a ton for a collimator just to align the focuser super precisely. In any event focuser tilt is pretty much taken care of in the collimation procedure

I think that in collimation at times people do become over obsessive and I should know as I suffer with mild OCD

At the end of the day we are dealing here with mass produced telescopes that suffer flex and all manner of other ills and when we use them we are looking through pea soup type atmosphere. Unlike some of our Amrican cousins who are operating in places like Nevada where you can pile on the power most of us are dealing with an atmophere where we are lucky to get to x130

Its important to get the scope as good as can be got but the key words thare are 'good as'

[TopHouse]

I have another idea for focuser alignment using a cheshire, ooo I can see you licking your lips already lol

[TopHouse]

For further tests etc i need something that i'm not sure exists, is there such a thing as a filter but that has clear glass in it and a reticule?

[orions-knight]

Nothing exists and I'm developing it.

OK

[TopHouse]

I think there's a serious opening for such an item. If there was such a thing i was going to try and beg borrow or steal one for further research into the camera method.

[orions-knight]

Sorry. It's not what I was thinking about.

OK

[Dipper]

Using a hardened steel washer is a common solution to the problem mentioned. However, I came up with an alternative solution of using two stacked perforated discs cut from a plastic container. The two discs make it easier to rotate the secondary during adjustment. More importantly, the plastic elasticity works like micro-springs. It allows to slightly screw-in one adjustment-screw without the need to unscrew the other two. I collimate my scope with an autocollimator which requires precise secondary mirror adjustments.

Jason

This is an old thread but I didn't want to post a new one and I'll just ask here instead.

Does adding some sort of material between the secondary mirror ant the adjustment screws on the spider have no negative effect on the focal length and optimal light projection in the focuser? What I mean is, if taken to extreme, you ad a two inch thick plastic between secondary and adjustments screws, the secondary will point the light well within the reach of focuser and you won't see anything as light will be projected on the wall of the tube. Now if you add something as thin as one milimeter or so - will it be tolerable and will there be no problems to point the light right in the center of the focuser?

[Jason D]

As long as you end up with a secondary mirror that is centered/rounded under the focuser, the thickness of the material added is irrelevant.

Jason