Collimator

[troppo]

Hello. I would like some advice on purchasing a laser 1.25" collimator. They seem to vary in price, so what is the good or bad with some of these. I have a 300mm Newtonian telescope f4.5. Focal length 1500mm.
Thank you.

[Jone5y (Steve)]

My advice would be to be wary of the GSO variant. Mine was so badly out of collimation itself that it is only barely acceptable now after I had adjusted it to its most extreme limits.

From what I've heard though, a good one is an invaluable piece of kit.

Steve

[GeoffW1 (Geoff)]

Originally Posted by troppo

Hello. I would like some advice on purchasing a laser 1.25" collimator. They seem to vary in price, so what is the good or bad with some of these. I have a 300mm Newtonian telescope f4.5. Focal length 1500mm.
Thank you.

Hi,

A tough subject with different views.(pun)

The basic unit is a tube with an ordinary "pen" laser in it. They can go out of alignment themselves and give you false results, so you might get one with 3 adjustment grubscrews on it which can correct this. For example

Guan Sheng deluxe Newtonian laser collimator...A$59.00 http://www.andrewscom.com.au/images/...collimator.jpg[/IMG]
TypePrice $(AUD)Laser collimator - Deluxe Newtonianreturn beam type. Latest version. Has half-silvered 45° mirror target for easy primary mirror collimation.Only $59.00


Then the next level up would have maybe a bit better laser unit, more stable construction and a 45 degree target window

https://www.bintelshop.com.au/Product.aspx?ID=8108

Some of them have a variable power laser for day or night use, and a safety factor

http://www.aoe.com.au/telescopemaintenance.html

Now all these have an issue, which is possible slop between the barrel of the laser housing and the focuser body. So there is a type to cope with that (this looks a very good unit BTW)

http://www.hotechusa.com/collimator.html

The question of whether the laser beam is coming out of the collimation tool in the right way is worth considering. There are sealed units which are more likely to be reliable, that is, you should not need to adjust the laser beam yourself:

http://www.astrosystems.biz/laser.htm

Now, there are different ways to use a laser collimation tool, which fall into 2 broad categories

- collimating the primary mirror by centering the return beam in the laser unit

- collimating the primary mirror by using a barlow lens with the laser collimation unit

It would bloat this post to go further here, but read up on

http://www.collimator.com/coltext.htm#newton

http://web.telia.com/~u41105032/koll...tm#barlowlaser

Hope this assists

[gjelke (Greg)]

Hi,
I recently purchased a rebranded GSO collimator from a Brisbane telescope store. It was a little out of collimation but I expected this and some tinkering is it is better but not perfect yet. I need to make a proper jig to align it with.

My advice is wherever you get one, haggle and compare prices and do pleanty of research on them. Understand exactly what you are getting and what results you should expect. There are pleanty of good articles on IIS and also a good video on Andy's Shot Glass.

For me, I was guessing my scope wasn't good but wasn't bad either. Some tinkering and I have gone from seeing Saturn and it's rings with limited defination of the bands to much better (perhaps 50% better).

Cheers and good luck and post us your results.

Greg

[JethroB76 (Jeff)]

I have the Astrosystems collimator mentioned above, which I find very good. It is however 2" not 1.25"

[PeterO]

Get a Catseye, not cheap but at f4 your going to need it if you plan to image.

[bmitchell82 (Brendan)]

Not quite true, i use my home made laser collminator and cheshire ep. and i can get quite accurate collmination with this accurate enough for a 40D and not to see any difference! Getting a cats eye system for somebody who doesn't know whats actually happening will be just as effective as a out of whack GSO delux! Dont get me wrong a cats eye system is the ducks nuts but when we are talking SW Dobs being mounted on eq6's with DSLR's its not quite a 14.5" Rcos with a SBIG st11k! my view on it its like putting a 600hp motor into a standard 1982 toyota corona!

My primary piece of advice before you try and tinker is understand what it is your adjusting aka understand what the LIGHT CONE is doing! and when your putting a laser in understand exactly what it is that your seeing. after that things become alot easier!

Originally Posted by PeterO

Get a Catseye, not cheap but at f4 your going to need it if you plan to image.

[GeoffW1 (Geoff)]

Originally Posted by bmitchell82

when we are talking SW Dobs being mounted on eq6's with DSLR's its not quite a 14.5" Rcos with a SBIG st11k!

Strewth I'll need to update the acronym list again. What is an Rcos?

SBIG I think we have got.

Cheers

[bmitchell82 (Brendan)]

Originally Posted by GeoffW1

Strewth I'll need to update the acronym list again. What is an Rcos?

SBIG I think we have got.

Cheers

hehehe i over shot the ST "L" 11k oops but the RCOS, CDK, RC all high end scopes the kind you pay though the ring for! but produce unreal photos.!