horrible laser collimator - how does everyone else do this??

[adman]

I don't think I will ever buy another laser collimator

I have just spent a couple of hours looking at my collimation as I had been relying on a laser to get it right....

well - even a cursory glance down the focuser without the eyepiece shows that it was about as far from being collimated as you can get!:mad2:

So I made myself a collimation cap and have redone it visually. Now it looks right, but I will have to test it tonight and see how close it is.

How do other people collimate their newts??

I am going to post the results from testing the collimation of my collimator to show how horrible it is....a warning to other unwary newt owners.

Adam

[bird]

The only thing to do with a laser is convert it into a barlowed-laser, there's plenty of info around on that, check it out.

I recommend the catseye collimation tools, they work very well for me.

cheers, Bird

[bmitchell82]

hehehe, don't you hate it when you have a rare moment of vision, and you go what was i thinking!

with your laser collimator, you can get it reasonably good, if you have one like the orion dulux or bintel varient pull it apart, get the laser out, unscrew the end where the laser exits the unit, with a piece of tin foil put a piece over so it covers the laser lense, screw the end cap you took off just before back on, with a fine tipped pen, or thick needle pierce a hole thats pretty much in the center of the exit hole, replace the laser back into the holder and collimate using a V block. you should now have a decent enough laser for getting your collimation about right.

If your going to stay with newts and want to use them for photography, head towards cats eye collimation tools, i have a XLK auto collimator and a XL Black cat cheshire. they are unbeatable and very quick N easy to get your collimation dead on without that element of maybe.

Otherwise there are a miriad of other tools out there that are pretty good

[mldee]

Hi Adam,

I spent a weekend getting my el cheapo Orion style ( I think) laser set up. As Brendan says, pull it totally to pieces and get a good feel for what goes where and does what. You need to have one that has the three collimator screws in the casing. I also tried the alfoil trick, although the hole in the casing was actually quite small, it was just getting the laser lined up with it that was the problem. Eventually got it though.

My eventual collimation was about 1cm circle at 2 metres. I could have got it better, but for me, that was enough for the first go. You do need the V block. I used two .90c rt angle brackets from Bunnings, screwed to a piece of wood.

As I said in a post on barlow laser collimation (with pics) in Beginners forum here the other day, it all came together and seems to work well. If you want any additional info or pics, etc, drop me a PM.

Clear skies tonight, I'm using the newly collimated Newt with QHY8+MPCC to do some galaxy hunting trials around the LMC. Looks good so far.

Cheers,
Mike

[mental4astro]

I use both a laser collimator and a 'cheshire' style eyepiece.

I use the cheshire first to sort out the secondary's situation first, and then the laser for the primary. The laser alone won't deal with secondary mirror's needs adequately.

I had only being using the laser for some time, and things where not working out the way they should. Then a mate suggested a cheshire, and 'presto', it all fell into place.

The 'cats eye' tool is very good too, as well as a barlowed laser.

You can make a deceptively effective 'cheshire eyepiece' from an old 35mm film canister with its lid. Use a 3mm or 4mm drill bit to make a hole through the centre of the lid and base. There are instructions on the net on how to use a cheshire collimation tool. This film canister version will take you to a point where the laser will finish of the collimation need. I use one of these diy film canister tools. Doubles as my focuser plug too.

[Vanda]

Who sells the catseyes in Oz? Thanks

[bmitchell82]

hey ian, you have to import them direct from Jim fly (cats eye) in the states. hes quick and good to deal with.

[Jason D]

Adam, laser collimators are not meant to align the secondary mirror placement under the focuser. It is possible to perform the laser collimation steps correctly yet end up with a secondary mirror that looks WAY OFF under the focuser. Bear in mind that the laser uses very small part of the secondary mirror surface. The secondary mirror edge is not referenced or used by the laser collimator. The laser will give you the same results whether your secondary mirror is square-ish or triangle-ish.

I uploaded the attached animation recently in this website. Every frame in the animation will give a perfect laser collimation picture but only one looks good.

Jason

[Manav]

Like Adam I'm getting sick of this as well! Tried GSO laser and the reflection shot out back missing the secondary altogather. I've been quite lucky since Brendan has the same lightbucket and the turd mount as me. I think I'll just order the XLK and continue my quest towards turning into an astrograph and a 1/2.

By the way I think I may have stuffed up the thread on the three screws on the secondary :( Probably worth looking for Bobs Knobs for those.

[Steffen]

Squaring up the secondary under the focusser can easily be done with a sight tube made from a film canister, as Alex mentioned. [EDIT: Sticking a sheet of white paper inside the tube opposite the focuser can greatly help with this.] Remember that this is not a critical adjustment (compared to collimation). If you get it slightly wrong you'll loose a tiny amount of light, but will still be able to bring the two mirrors into collimation. So eyeballing it through a sight tube is all you need to do. You should take a vernier calliper or ruler to the spider though, to make sure it's centered in the tube.

If the reflected laser beam from the primary misses the secondary then that's not because the secondary is out of place (it couldn't be out of place by that much). Simply proceed by titling the secondary (using its collimation screws) until the laser spot hits the primary's centre, then tilt the primary until the beam folds back on itself all the way up.



Bob Knobs are definitely recommended. They make collimation much easier and safer.

Cheers
Steffen.

[bmitchell82]

hahaha, :) my poor old light bucket is getting a thrashing lately the only skywatcher bits is the tube, secondary mirror holder and the primary mirror/cell.... in about a fortnight the secondary will be changed for my new one that im making and a new orion optics primary mirror cell will render the scope to only have a skywatcher tube :) (and thats on the list of replacement).

the cats eye gear is very nice to use and it took me about 30 min to get the whole thing together and collimated from a compleate dismantle!

I will agree with steffen that the white paper behind the secondary is legendary, and makes centering and squaring of the secondary mirror very easy.

[ausastronomer]

This is 100% correct.

Importantly even if your laser itself is collimated it can't handle the secondary mirror positioning from scratch. Further, you can adjust the tilt of the mirrors to have the laser striking back on its exit point making the telescope appear collimated, when in fact it is not even close.

The Tectron Tools are excellent (if you can still buy them), as is the cat's Eye collimating system. The Orion combination tool is a good cheaper option, but can be a bit disconcerting for a beginner to use. The more expensive systems like Tectron and Catseye, which use a separate sight tube, cheshire and autocollimator, are easier for an inexperienced person to learn what's going on.

Cheers,
John B