Laser collimators

[Dreadz]

Have been trying to get to grips with collimation using a cheshire & cap and am (I think!) getting the hang of it however its not ideal for checking collimation outside in the dark so am considering buying a laser. I know that the cheap lasers will probably cause more problems than they'll cure so have been looking at the baader mk3 or the hotech sca but not sure which to go for or should I try to stretch the budget that bit further for the howie glater?

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[wookie1965]

Very easy in the dark with a Cheshire just shine red torch at the reflective part of your Cheshire when looking through it.

[oldpink]

I bought a laser collimator from E bay, checked it for collimation and it was pretty accurate
took me 5 minutes to get my collimation sorted and made doing the primary easy as you can see the beam 
get one that has a variable setting for night time use, the one I got has 7 settings

[Mem]

I have a Cheshire and was happy collimating with it, I have always been intrigued with lasers and just wanted to improve the accuracy of my collimating in order to compliment my Cheshire, after much research and reading advice and reviews I bought the Hotech colimater, it's very, very good and very accurate. The reason why I never went for a laser first was due to a lot of people stating that the Cheshire was a cheaper version and just as accurate, also a lot of people I have spoken to advised against sub £100 lasers as not worth the money and inaccurate.

I first use the Hotech and then use the Cheshire to check accuracy and correct collimatin, it's never let me down and I was never as accurate with the Cheshire on its own!

My advice is buy the one with the 2" adapter and the cross hair version! I have a Lightbridge 12 and have spent a lot of money on upgrades and eyepieces, the Hotech is well worth the invesment.

[wookie1965]

I had a laser the 7 position one it was out of collimation which i found out when i checked with a Cheshire, Its now in the bin i couldn't collimate it for love nor money. If you are going to buy a laser get the Hotech as they are bullet proof and very accurate.

[oldpink]

yes a badly collimated laser will cause more problems that it solves
mine was Ok out the box so no worries, but I collimate lasers often as I use laser scopes
and also have high power show lasers for projection I use with my PA & lighting rig
so I'm well used to aligning them when they go off

[wookie1965]

yes a badly collimated laser will cause more problems that it solves

mine was Ok out the box so no worries, but I collimate lasers often as I use laser scopes

and also have high power show lasers for projection I use with my PA & lighting rig

so I'm well used to aligning them when they go off

Wish i had known i could of asked you would you of minded collimating mine would have paid postage and any monies you wanted for doing it.

[Langy]

I got the laser from STL, it wasn't too far out.

There is a forum post I created with all the pics etc. especially as I don't have a center spot on my primary.

If you have a Cheshire already and buy a laser that you can collimate itself then you can compare the two in daylight to see if there is much difference. Oh I created a lovely little lego jog to test my laser, all in the post. Once you know how the two compare you can easily use the laser at night to see if you are far out.

[Langy]

Link below to the forum post I created.

http://stargazerslounge.com/topic/210348-first-collimation-newbie/?hl=%2Blaser#entry2249130

[albedo0.39]

I've collimated all sorts of scopes in the last 5 years and still find a red torch at night with a Cheshire just as accurate as anything... But... A barlowed laser is also a great help in the dark.

I even once did a lecture on how to get the best in accuracy at an SGL star party a few years back... PM me if you want the notes.

Rgds

[Dreadz]

Anyone used the howie glatter? Is it worth the extra cash for the ability to project the grid/rings to aid collimation??

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[Dreadz]

Also am I correct in assuming the only way to check the primary centre donut positional accuracy on my 250px is to remove the primary cell? (Not something im keen on really!)

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[oldpink]

Wish i had known i could of asked you would you of minded collimating mine would have paid postage and any monies you wanted for doing it.

my first attempts years ago were dreadful very easy to muck it right up

you really need the right tools and a jig, I built my own using a couple of bearing races I had to allow smooth rotation

and its very stable so makes life easy as does a decent set of Jewellers screwdrivers

[oldpink]

Also am I correct in assuming the only way to check the primary centre donut positional accuracy on my 250px is to remove the primary cell? (Not something im keen on really!)

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short answer is yes

you would need to measure it to see how accurate it is

but I'd say its most likely pretty much accurate enough out of the box otherwise its pointless having it there

[Dreadz]

Does using a laser for the primary collimation overcome any inaccuracies in the position of the donut? Using a Cheshire yr using it as a visual reference but wouldn't a laser be reliant on the optical centre of the mirror and not the donut applied to it?

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[oldpink]

if your do a laser collimation and your donut is off you will still be out
the laser points where you tell it to point by your adjustments to the mirrors

if your donut is off you will be off centre no matter what you use to collimate

[Dreadz]

I can understand that if you use the laser to position both mirrors but if you align the secondary using a collimation cap and then use the laser just for the primary then wouldn't the donut become irrelevant?

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[oldpink]

never tried that
but I suspect from my knowledge of lasers and collimation the laser path to return to its origin would be off if your donut is off centre

as thats the first step you do, move the secondary till its in the middle of your donut
then move the primary to reflect the laser back to the source

[wolfpaw]

Lasers are, IMO, an absolute waste of money. I had one (Seben) that I collimated to within about 2mm at a distance of around 3 metres. It still showed that the collimation of the telescope was off despite the fact that the Cheshire showed that it was pretty much spot-on. I went with the Cheshire as I preferred to trust my eyes.

[ScottS]

I only use my laser with the Barlow.

[Joseki]

I recently purchased a baader laser one. Prior to that I have used a combination Cheshire tool. I really like the baader tool, and I find it easier to tell when it's properly alligned. Btw the Baader one says there's no way to collimate it (and that it doesn't need any adjustments).

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[Langy]

I recently purchased a baader laser one. Prior to that I have used a combination Cheshire tool. I really like the baader tool, and I find it easier to tell when it's properly alligned. Btw the Baader one says there's no way to collimate it (and that it doesn't need any adjustments).

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I would still check that it is truly in line, a few lego bricks makes a good base to test it on. Mine mentioned nothing about adjustment but the adjustment screws were hidden under some rubber filling, so you may well find that there are adjustment screws just hidden.

[Charic]

Since buying my laser ( £24 from Sky's unlimited)  It only gets used at night, Barlowed, to check the primary, because I cant look down the focuser and adjust at the same time, because of reach.

My only concerns for anyone buying a laser is to ensure that it can be user collimated, and that there is no play once fitted to the telescope? If when in-situ  it scribes a spot within the donut/doughnut/centre spot, then you've got it sussed.

I manually align the secondary mirror to the central axis of the focuser tube, using a film cap. You can then use a laser to adjust the tilt of the secondary. This to place the laser spot on the primary centre spot. Next I would  insert a Barlow to spread the laser beam over the surface of the primary. This sends back a reflection/shadow of the centre spot which is simply aligned around the hole on the lasers target face. But as already stated, I now only use the laser for the final primary adjustment.

I`m thinking of purchasing a collimation sight tube with cross hair to see if its possible to align the secondary mirror any better than with a film cap. Problem is, the size of the tool? There's long and shorty versions, but now I find out that a sight tube has a formula =  Inner diameter times the focal ratio!!!!!! Why cant things be so simple. Its either a DIY version, or they can be bought as adjustable, meaning it could be used for any scope?

[66mikeg]

I prefer to get set up early while it's still light and check the collimation with a Cheshire, I may be lucky but in the 2 years that I've had this 'scope it has only needed minor tweaks on a couple of occasions and star tests as well as I can see

[wolfpaw]

Since buying my laser ( £24 from Sky's unlimited)  It only gets used at night, Barlowed, to check the primary, because I cant look down the focuser and adjust at the same time, because of reach.

My only concerns for anyone buying a laser is to ensure that it can be user collimated, and that there is no play once fitted to the telescope? If when in-situ  it scribes a spot within the donut/doughnut/centre spot, then you've got it sussed.

I manually align the secondary mirror to the central axis of the focuser tube, using a film cap. You can then use a laser to adjust the tilt of the secondary. This to place the laser spot on the primary centre spot. Next I would  insert a Barlow to spread the laser beam over the surface of the primary. This sends back a reflection/shadow of the centre spot which is simply aligned around the hole on the lasers target face. But as already stated, I now only use the laser for the final primary adjustment.

I`m thinking of purchasing a collimation sight tube with cross hair to see if its possible to align the secondary mirror any better than with a film cap. Problem is, the size of the tool? There's long and shorty versions, but now I find out that a sight tube has a formula =  Inner diameter times the focal ratio!!!!!! Why cant things be so simple. Its either a DIY version, or they can be bought as adjustable, meaning it could be used for any scope?

How do you remove the slop when it's in the focuser? I found that no matter what I used to try and make the laser fit tightly into the focuser it needed only the very slimmest of movements to make the red dot move around on the primary.