Ok you Dob people....

Some good stuff in those links.
I think it'll be out with the Cheshire first, make sure everything is aligned properly before laser collimating as well to check.
Mt highest powered eyepiece is a 7mm, so that just gives me about x260.
I do have a x2 Barlow, but I'd just use it to throw at stary cats as it's a pretty cheap crap one.

Dave L - Pointing the scope at Polaris avoids the need for motorised tracking ability, and it's plenty bright enough.

A cheap crappy Barlow will work just fine for star testing.

Phil.

Is the seeing ever good enough in this god forsaken country to do a star test!!

I've got a 12in Dob and and have been using a laser collimator from the very begining. I very quickly found out that they themselves required collimation. This I did and from then on I was using the collimator straight for secondary alignment. I wrapped a single layer with no overlap of insulation tape around the 1.25" barrel to eliminate what seemed like a tiny amount of slop between the 1.25" barrel and the 1.25" adapter in my focusser. This I thought was enough for secondary alignment.

I then used the barlowed laser method for collimating the primary. This is reckoned to be as good as cheshire collimation of the primary but with the benefit of being abled to be performed at night. There are professional Collimation tools that use this method such as the Howie Glatter with Blug which is basically a barlow, target and laser in a self contained unit. But if you have a barlow(the cheaper the better actually so you are not wasting or risking scratching a good one), and a laser you can make one yourself. Laser in the Barlow, make a white target that slots in at the other end in front of the lense (I used a Premier Dairies Milk carton cap with a small hole in the middle for the laser to shine through) Pop in the Barlow/Target/Laser combo. You will see a large area of diffuse laser light projected onto the primary. As long as some of this patch is over the primary centre marker donut then there will be a shadow of this donut ring projected back up to the barlow target. So with a little makeup mirror or somesuch you can look up the focusser drawtube at the barlow target and you will see the white barlow target illuminated by the reflected diffuse laser light from the primary.....along with a shadow of the donut/ring. You then collimate the primary by centering this shadow of the donut/ring around the hole in the target. This method works even if the laser is not collimated perfectly (though you need it perfect for the secondary) and it works even with focusser slop. Even if you move the laser and twist it bend it in the focusser, the patch of diffuse laser will move but the shadow of the ring wont.

So!......I was relying 100% on the laser and didn't bother with my cheshire anymore and was doing all my collimation at night at the beginning of an observing session.

Big mistake on my part. The other night I felt something was off.

1. I found my laser was out of collimation again. (not important for my barlow primary collimation but very important for secondary collimation. I haven't banged or dropped the laser but it does seem that one still needs to check the laser collimation regularily

2. I found that while I had eliminated 1.25" barrel/1.25" adapter slop with the tape, I actually still had drawtube slop! ie. The whole drawtube would tilt ever so slightly with the weight of the laser!!

3. I somehow forgot that while one can still align the unbarlowed laser spot during secondary collimation with the donut/ring, that does not necessarily mean that the rotation of the secondary is right. In other words, I thought my secondary collimation was fine once I adjusted my 3 secondary thumbscrews and got the laser dot centred on the primary. Turns out that over a number of sessions my secondary was gradually rotating away from the foccuser with each collimation. When I popped in my sight tube I realised that I could no longer see my primary reflection in its entirety.

So my currrent reasoning is that collimation of my laser is moot seeing as drawtube slop will lead to inaccurate secondary collimation anyway. So what I am doing now is use my sight tube cheshire with a torch to check secondary rotation(Full primary relection centred) and to make sure my secondary is centred each and every time I collimate. Then use my simple plastic cap tool with the little hole to align my secondary with the primary marker/ring/donut. ie no weight to speak off to induce focusser/drawtube slop, and finally use my (out of collimation laser ) with my barlow to do my primary collimation.

As for star collimation. Have never been able to do it. Either I have a rough mirror surface or the seeing has never been good enough for me. Put it this way. At lower powers I see point stars but for instance when I use my 10mm sirius plossl for my star alignment for my object locator, I use Polaris for one of the stars. My 10mm in my scope gives 150x. It is more or less always a small furry disc when focussed. If the seeing is particularily bad it is a larger furry disc overlapping with its binary(real or optical??) companion. They say 40x per inch of apeture for star tests. That for me (480x for me) would mean using my highest power 3.5mm hyperion which gives 429x. At that power I know I haven't a hope of seeing a star as a point non furry source!!

Keith...thanks a lot for that in depth description..that is going to be really useful for me as I seek my Holy Grail of set-ups.
This is a great example of how useful an Astronomy board can be...not only for beginners...but for really useful practical information at all levels.

Just to follow up.
I took some of the advice, read up on all the links posted and spent an evening with my Cheshire and the Dob.
I got everything aligned pretty closely, and when I then went to use the laser collimator I barely had to touch anything, because everything was sweet...so that was a good indicator I was doing OK.
I got the Dob out last night... a pretty good night for us up North.
No dewing up...my Telrad stayed clear for a good 5 hours, and normally it starts dewing after about 30mins-one hour.
I'm very pleased with the results.
When the atmosphere steadied every so often i'd the best views I've ever had of Saturn, razor sharp with cloud belts, 5 moons on show and the rings almost had a 3 dimensional quality, all at about x270.
In fact my 7mm Nagler, which was always a disappointment, really worked well.
Other highlights were the Eskimo Nebula, M35, The Silver Needle Galaxy, the discernable spiral structure in M51 and M101 and many others.
The 16" Lightbridge, given good conditions, is a wonderful telescope.
There's some coma with my panoptic 27mm for about the last quarter round the edges, but that's only to be expected in such a fast reflector (F4.5)
I can't wait for some really dark skies, as I was pulling faint fuzzies out everywhere without any problems at all.
Thanks to everyone for their help, it really did make a difference to the scope and to my viewing pleasure!

OK as a complete novice to the subject of collimation, (only purchased 10" starhopper last week) I did astar test using polaris last night but the seeing was a bit misty! crystal clear views of the moon and that was pushing magnification to 160x (15mm and barlow2) around 8.30ish saturn was still down in the murk but when i did image it - i could clearly see the division between the planet and the rings but not much colour varience on the surface.

Question: is the last 2 nights less than ideal to collimate a scope due to moisture in the air?

and how do I stop myself breating on my eyepieces causing my blood pressure to rise?

declan