laser collimator which is the best.

[ukbigd]

Which is the best laser collimator to buy, Looking to buying one asap. I Have the normal collimating tool, But cannot seem to get that sweet spot when you know its spot on, I presumme you know what I mean about "sweet spot" lol..............

At the moment i have spent a bit of time collimating my Dob but looking at Saturn last night it was still a bit fuzzy and no colour to it, not what you expect to see using a 10 inch Dob..............

[John]

The Baader Laser collimater seems to be quite popular but I've not been too impressed with mine. I'm now only using it to check the tilt of the secondary. For the primary adjustments I'm finding a simple cheshire eyepiece more effective and frankly more accurate when I get the scope under the stars.

John

[ukbigd]

I was going to say when i bought your 8"Dob off you jahmanson, The dob was spot on, So I have every faith in what your saying to be true m8.

[johninderby]

I've got the Baader one as well and only use it to adjust the secondary. I use a simple Celestron Collimating Cap to adjust the primary and find it's much more accurate.

One problem with any laser collimator is that it also needs collimating first before you use it in the scope. I put mine in a small lathe with the laser shining through the headstock and onto the wall and then rotated it by hand to check that the laser spot stayed in one place. If it doesn't it can be collimated much like a secondary mirror using the adjustment screws.

John

[Kai]

Ive heard good reports of the Hotech Lasers as they are self centering.

It would be interesting to see how they perform in comparison to other Lasers.

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

[Ben Ritchie]

I agree with John - I prefer a simple cheshire eyepiece.

I have a Catseye system turning up in the post sometime soon, so i'll see how that compares

[Kai]

That the other thing i want to try Ben , the Catseye.

I know James uses one and i hope i can persuade him to take it to SGL4 and use it on my Dob.I have heard its so accurate that yuo can end up chasing temperature changes during the night.

[ukbigd]

can anyone supply a link for this catseye, in terms of purchasing it.....

[ZOG]

The trouble, it seems with any collimator is the focusser, unless you have a vey high quality one. The red dot on my laser and the cross on the cheshire wil end up in differnent positions depending on which screw I tighten first in the focusser, and how tight I make them. I now have a routine of tightening the bottom screw first, then the top one and making sure they just make contact. I'm still not 100% sure that it's spot on, but a star test usually looks ok. that is, if my eye is collimated properly as well

[acey]

http://www.catseyecollimation.com/

To use it you need to stick a triangular marker on the primary.

You say Saturn was fuzzy and colourless in your 10", I found it the same in my 12" flextube which was in perfect collimation. The cause was poor seeing and stray light. Can't do much about the former but the latter causes diffraction spikes to be bigger and brighter, and this produces a lack of contrast. The answer in that case is not collimation but baffling (and a shroud if it's an open-tube scope). Of course there's also eyepieces to consider.

As to collimation, like the others I use a laser for the secondary and a cheshire for the primary. My laser is a SkyWatcher, the cheapest I could find.

If using a laser for primary adjustment it may be best to use the "barlowed laser" method which avoids the problem of focusser slop:

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

Andrew

[johninderby]

I agree with the last post. Unless you've got a good focuser that won't affect the collimation as the drawtube is moved, trying to get perfect collimation can be a waste of time.

John

[James]

i hope i can persuade him to take it to SGL4 and use it on my Dob.I have heard its so accurate that yuo can end up chasing temperature changes during the night.

I will be bringing it and yes, the level of accuracy is quite something. One night I was waiting for some clouds to clear as the scope was cooling down fast and I could see one of the stacked triangles move minute by minute as the scope cooled.

The advantage I find with the Catseye system is that once it's done I know that the collimation is as good as I can get it and for those of us with OCD it's good to know that.

I also used it to compare with my Baader Laser and the Baader agreed 100% but the Catseye is based on four passes of the light from mirror to secondary to autocollimator to secondary to mirror and so on whereas the laser is just one pass.

There are caveats of course. If your focuser is somewhat sloppy then the Catseye system (and a laser for that matter) will be so precise that you'll never quite be able to get everything to agree...

James

[kniclander]

I had a baader which ceased function after about a year. My impression is, if you want a laser, you need to buy quite a high end one, otherwise you'll get junk. In reality, a collicap and a cheshire are all you need and without doubt more accurate than a cheap laser.

[Doc]

In my experience a laser is only as good as your focuser.

If you have slop in your focuser then your laser is worthless.

[calibos]

Howie Glatter Holographic Laser and Blug (Barlowed laser target)

Accept no substitutes. You're talking about 150. Worth every single penny IMHO. 3 times the price of a cheap chinese laser collimator. 1/30th of the frustration

[weareborg]

Just found these sites

http://www.astronomyasylum.com/accessories.html#Collimation_Eyepiece

http://www.atmsite.org/contrib/Carlin/collimation/kolli2.htm

which could save you a few quid.

Andy

[Astronut]

I used to have a Baader laser but I've found that a simple cheshire gives much more consistent results. I've since moved on to a Catseye system. Once the collimation is done I find it much easier (ie. more accurate) to fine tune the alignment of the stacked triangle reflections using the focuser base adjustments ie. leave the secondary alignment alone. Adjusting the secondary is the most fiddly and frustrating part of collimation (even with Bob's Knobs fitted).

I'll have my Catseye tools with me at SGL4 too. Anyone is welcome to check 'em out if James is busy imaging

[James]

.... if James is busy imaging

Six months ago I wouldn't have believed it if anyone had said that.

At SGL4, if it's clear I'll get some visual done. We'll also have a variety of collimators with us (Hotech, Skywatcher, Baader, standard Cheshire eyepieces, Catseye's Cheshire & autocollimator) for anyone to have a look at/play with.

James

[The Warthog]

I have held out for ages the fact that a Cheshire collimator is as accurate as any laser collimator, and no more difficult to use. I know people who collimate with a laser, and then slip a Cheshire into the focuser to check it. My Cheshire cost me $27, and works fine.