cheaper, unbranded laser collimators

[Jimtheslim]

are these any good? There's a few on ebay that are half the price of the branded ones such as skywatcher. Are they up to much or best avoided?

 

[Ally8446]

The one thing to remember about most collimators is that they require collimation themselves.  If you can do that then it makes little difference.  

Ally

[Ally8446]

One other thing. If you can collimate/centre your secondary manually (laser collimators cannot collimate your secondary unless your using a very high spec setup i.e Howie Glatter with holographs) then collimate your primary using the Barlow method then any cheap old laser collimator will work. 

Ally

[Knighty2112]

Just be careful when you collimate your Newt. Some lower models (such as the Celestron Astromaster 130eq for example) have their secondary mirror offset when viewing through the focuser. On these kinds of model you do not adjust the centre locking screw that holds the secondary mirror in the right position to achieve focus. You can slightly adjust the three other screws/bolts around it to adjust the secondary collimation to line it up to the primary mirror. I made the mistake of following what everyone on the internet said in that you have to have both the secondary mirror and the primary mirror centered. It took me ages to get the scope back to a decent level of colimation after that, and I'm still not 100% convinced it is back where it was originally.  

[Knighty2112]

BTW: I have a Seben branded laser colimator that cost around £25. Works OK, only problem when I got it was the battery was flat, so had to go out and buy a new one. Collimation seems spot on with the laser itself. 

[Jimtheslim]

I was considering buying askywatcher 250 dob. I would like to learn to do it manually, but if it's going to be a long distance between the primary mirror and eyepiece I thought about ordering a laser to cut out some of the faff.

[Knighty2112]

That scope should be OK to collimate in the normal way, so should have no problems there hopefully. As my primary scope now is an ST120 frac I rarely use (if ever) the Astomaster reflector now. However, in May I'll be getting a second hand Celestron C6-N reflector as well, so I'll have to brush up on my collimation skills again!  

[rockystar]

one thing about mine is that the laser is actually too bright, so it's difficult to see if it is in the centre of the primary when adjusting in the dark. I end up shining a bright torch down the tube to bring the laser light to a point.

[John]

1 hour ago, Knighty2112 said:

Just be careful when you collimate your Newt. Some lower models (such as the Celestron Astromaster 130eq for example) have their secondary mirror offset when viewing through the focuser..... 

All faster newtonians have an offset to the secondary mirror. Most mass produced scopes have the offset built into the way that the secondary is mounted so you don't need to adjust it yourself.

On the original topic, I have a Revelation laser collimator which is one of the cheaper models. It did need collimating itself though so that needs to be taken into account if buying a low cost one.

Most of the time now though I use a cheshire eyepiece to collimate my 12" dob.

 

 

[Knighty2112]

26 minutes ago, John said:

All faster newtonians have an offset to the secondary mirror. Most mass produced scopes have the offset built into the way that the secondary is mounted so you don't need to adjust it yourself.

On the original topic, I have a Revelation laser collimator which is one of the cheaper models. It did need collimating itself though so that needs to be taken into account if buying a low cost one.

Most of the time now though I use a cheshire eyepiece to collimate my 12" dob.

 

 

Thanks John. Never knew that it applied to all fast Newts. Learn something new every day!  

[Knighty2112]

1 hour ago, rockystar said:

one thing about mine is that the laser is actually too bright, so it's difficult to see if it is in the centre of the primary when adjusting in the dark. I end up shining a bright torch down the tube to bring the laser light to a point.

Mine has seven level settings. However, never used it at night so don't know how well it performs to use then. Always done the collimation in the day time, with a setting of 6 or 7.

[Ally8446]

1 hour ago, Jimtheslim said:

I was considering buying askywatcher 250 dob. I would like to learn to do it manually, but if it's going to be a long distance between the primary mirror and eyepiece I thought about ordering a laser to cut out some of the faff.

What scope do you have now ?

Collimation is really simple and straightforward to do using a Cheshire (once you know what you're looking at, in respect to the reflections).

I am NOT technically minded whatsoever but it only took me a short time to figure it all out. Sometimes when I just want to 'fiddle and tinker' I'll knock both mirrors out of collimation just so I can recollimate it. ....but then I'm just sad ??

Ally

[blinky]

Interesting topic, my Baader collimator laser has just died and Im debating buying a cheap one from flabay - surely once you have collimated it they are all the same?  Not sure I would buy an expensive one again - only used the baader a couple of dozen times.

[blinky]

Also, these: http://www.ebay.co.uk/itm/Next-Generation-Laser-Collimator-with-1-25-Fitting-2-Adapter-for-Telescopes-UK/191839566058?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36243%26meid%3D50b30219d408445ca1275f790f71f908%26pid%3D100005%26rk%3D1%26rkt%3D5%26sd%3D281742991419 Look to me exactly like the Skywatcher ones...

[Jimtheslim]

5 hours ago, Ally8446 said:

What scope do you have now ?

Collimation is really simple and straightforward to do using a Cheshire (once you know what you're looking at, in respect to the reflections).

I am NOT technically minded whatsoever but it only took me a short time to figure it all out. Sometimes when I just want to 'fiddle and tinker' I'll knock both mirrors out of collimation just so I can recollimate it. ....but then I'm just sad ??

Ally

I currently have a 90mm frac. Collimation doesn't worry me too much, in fact like you I think I look forward to the challenge (as well as researching and buying more equipment). I just wondered if there was a lot of difference between a laser worth £80 and one a quarter of that price. Collimating a collimator, or at least worrying about whether it, and thus the scope, is in collimation does concern me a little. Maybe I'll just go for a Cheshire or make a collimation cap myself. That's if I ever get round to buying this new scope

[Dave In Vermont]

As was said - often the laser-collimator will need collimating itself. To do this task, you need to access three little screws with an allen-wrench. And some of these simply don't have them where you can get at them. Asking a seller, if they don't specialize in astronomy-goods, can draw a blank stare. But the eBay one above that Blinky posted the link to does have them. They are under a plasticy-type putty, and one is under the label. Simply pop-out the putty and peel back the label.

It also has adjustable brightness settings - from off to '7.' I can personally endorse that cheapy one. It's a nice little unit! And it has a 2" adapter - good deal for £17.49.

I actually enjoy collimating scopes, and have tested many lasers. Most costing far more money. The eBay one is my favorite.

Dave

[Paul73]

At that price it looks pretty atractive.

i've always used a Cheshire. Would I get better colimation by swapping to a laser unit?

Hope that this isn't too far off topic?

Paul

[Dave In Vermont]

I always check my collimation with both a laser and Cheshire. Unless I'm out in the dark - then the Cheshire will wait until I'm back indoors. But the two always match. Is one better than the other? I'd be inclined to say they more compliment each other. But I do usually suggest that people who are new to collimation to learn with a Cheshire. Besides - the laser isn't designed to set the secondary-mirror with. Unless it's some very expensive models that can use holographic programs and other bells & whistles.

A laser is an excellent tool for checking things with when out in the field. And the adjustable one is ideal for dark-sky sights where a regular laser can be too bright - even if it is red-light.

Dave

[Jimtheslim]

I thought the laser did both the secondary (get the dot in the centre of the primary) and the primary (get the dot to return into the bullseye of the laser eyepiece)?

[Ally8446]

As Dave and I have mentioned,  no,  a laser cannot tell you if your secondary is round and centered.  You can only do that with a colli cap or Cheshire.

If your secondary is out of alignment you can still get the laser dot to sit perfectly on the centre of the primary.  Unfortunately the scope will still not be collimated because your secondary is out.

Put your faith in a Cheshire, it'll never run out of batteries ??

[Jimtheslim]

I see, all the stuff I've read and videos I've seen about laser collimators suggest it's far more straight forward than in reality then, all seem to imply that you only need to line up the laser in the primary and then return to the target and then your fully collimated. I'm guessing collimation is probably not difficult once you know what your doing, but the more I read about it the more tricky it seems.

[Ally8446]

Have a peruse of this explanation of collimation. It helped me tremendously.

http://www.garyseronik.com/?q=node/169

Ally

[Jimtheslim]

11 minutes ago, Ally8446 said:

Have a peruse of this explanation of collimation. It helped me tremendously.

http://www.garyseronik.com/?q=node/169

Ally

Thanks, this seems useful. This guide suggests you adjust the primary first and then the secondary. Everything else I have read/viewed says you need to do the secondary first. I take it this doesn't matter an awful lot? See what I mean about all the confusion?!

[John]

1 hour ago, Jimtheslim said:

Thanks, this seems useful. This guide suggests you adjust the primary first and then the secondary. Everything else I have read/viewed says you need to do the secondary first. I take it this doesn't matter an awful lot? See what I mean about all the confusion?!

That is confusing. I always check the secondary 1st and then the primary.

My understanding of what Seronik is suggesting is rough primary alignment / secondary alignment / final primary tweaking. Maybe he is assuming a highly un-collimated scope ?.

When I've put my 12" dob out I never seem to need to do anything other than a small tweak to the primary - it's the heaviest piece of glass so more prone to shifting than the secondary.

 

 

 

[Ally8446]

28 minutes ago, John said:

That is confusing. I always check the secondary 1st and then the primary.

My understanding of what Seronik is suggesting is rough primary alignment / secondary alignment / final primary tweaking. Maybe he is assuming a highly un-collimated scope ?.

When I've put my 12" dob out I never seem to need to do anything other than a small tweak to the primary - it's the heaviest piece of glass so more prone to shifting than the secondary.

 

 

 

Sorry about that.  My point was how he explained about secondary collimation and there being no need for a laser. 

My bad. 

Ally