Collimation for a newby

[Legin (Nigel)]

Hello...

Ok so I got my first decent scope the other week and I eagerly unpacked it, set it up and dragged it outside. While the telescope is good it did show signs of being in need of collimation.

All the stars showed distinct collimation type smudging. I tried doing a bit of a star collimation as per my telescope manual but I had somewhat limited success.

So I went out and got myself a laser collimator thinking it was the easiest thing for a beginner to learn to use. Anyway I can not seem to get my collimation right.

So today I went and purchased a sight tube with what appears to be viewing hole in the end of it. I tried to collimate the scope again.

Anyone know any good tuturials for collimation. I am finding it a bit confusing. I do get the impression once I learn it I will find it easy but learning it can be tricky to say the least.

I seem to have it all lined up at least OK'ish but I wouldn't mind learning how to collimate to a point where it is pretty good. My telescope may not be the best in the world but I would like to make it the best it can be and in my eyes collimation is IMPORTANT.

One thing that really confuses me is the offset of the secondary mirror. I know basically what it is but I am not entirely sure if I need to check or adjust it. I assume it needs to be at least 99% accurate for the telescope to have good collimation.

Any advice and or tutorials would be greatly appreciated.

I know one day I will say "Collimating is easy" but at the moment I am somewhat confused. Forgive me if I am asking a simple question but I really want to learn to collimate my scope "just right" .

[Legin (Nigel)]

Just for the record I got a Celstron Omni XLT 150 (6inch)

[PCH (Paul)]

Hi,

if you have a dob or a newt, the following link may help to explain what's required ...

http://www.andysshotglass.com/Collimating.html

Hope it helps,

Cheers,

[astro_nutt]

Hi Nigel
Just a couple of tips to make collimation easier...
Find a place that is quiet and without distractions..kids..pets..etc
A bedlamp with a white shade would make a good light source.
Make sure the tube is secured hoizontally whilst you work.
Make sure all tools are clean and have a strap through the handle which can be fastened to your wrist to prevent any accidents to your mirrors..etc
Keep a record of the number of turns for each adjustment screw for each mirror.
Never force a screw that is too tight!!..or overtighten them..just firm enough..
Take your time and make sure you have a break when you feel like one!
Cheers!!

[Kevnool (Kev)]

One point to add i hope your new scope (only if it is a reflector) that the primary mirror has got a centre ring on it ,if not you`ll have to get it centred or your laser colimator for the secondry and your cheshire for the primary wont have anything to align to.....cheers Kev.

[Legin (Nigel)]

Ok this is a view through my collimation tube eypiece.

I am a bit confused exactly what is what at this point. I have viewed a few online tutorials but things seem to look a bit different to me. I am starting to understand some of it but I just want to make sure I have it at least 90% right, in my head, before I do too much poking around and adjusting screws etc.

Oh and my telescope has a nice little circle in the center of the main mirror. The laser collimator seems to point right to it when I put it into the focuser so it looks pretty good from there. Though the scope is a little out of whack I suspect it only needs a bit of tweeking

Ok this is as I figure it all out. The large (blury cross hairs) roughly at 45 degrees are the ones from the Collimation tool itself. The large white area around the outside is the primary mirror. With the smaller shiny bit inside being the secondary mirror. Am I even remotely right?

Also can anyone spot any obvious problems I should know about?

Thanks in advance

Something else I have come across my sight tube seems to be a Skywatcher version of a combined "Sight Tube" and "Cheshire" collimator. I didn't get any instructions with it so I am learning from scratch. I just thought that might be of help. I have also heard that barlowing the laser collimator is worthwhile (any comments). I think the barlow idea is a good one myself but I am only new to this game so I could be wrong. At least it seems good in theory.

[Jen]

Hi Legin

Hope you get your scope right i had heaps of troubles trying to do that too then silly me in the end was turning the wrong screws hahaha
once you do it once it will be a breeze i think

[Kevnool (Kev)]

Nigel when you adjust the laser up by the 3 secondry mirror screws in the centre of the ring on the primary mirror .....take the laser out then put the cheshire in and then by adjusting the 3 screws at the back of the scope align the primary by putting the crosshairs in the centre ......but this is where a lot of people fall down,what you gotta do is repeat the process over and over until you cant make any more adjustments,sometimes it could take 5 times back and forth between the primary and secondry mirrors to achieve colimation...But thats just me others do it different.

Have a good grip on that screwdriver when adjusting that secondry ,you dont want to drop it in there or i`ll here you from here....cheers Kev.

[Kevnool (Kev)]

Have you given it a shot yet jen.........Cheer s Kev.

[Legin (Nigel)]

Ok I have the little red laser dot of the laser collimator lined up with the circle on the primary mirror. That seems to be the easy part. Just for the record there is a little slop when I focus right in and out, especially all the way out. But it seems at least ok around where I typically use it. Also tightening the little screws around the focuser can even seem to make a difference (if that makes sense).

Oh well I seem to have things lined up at least to a point where the secondary mirror is at least pointing in the right direction.

The circles I see through the sight tube confuse me though. As I read through various tutorials and what not I seem to have different circles. Maybe I am looking at it all wrong . Forgive the simple questions about collimating but if I don't ask I don't learn right?

[Starkler (Geoff)]

Legin try this:

For a start put away the laser collimator until this is sorted. It can introduce errors that can confuse the issue and it doesn't help initial alignment of the secondary.

Step 1: Align the secondary under the focuser.

Place a piece of paper between the secondary and the primary to block the view so that all you can see is the secondary. Also place a piece of paper against the tube wall opposite the focuser to make the secondary easier to see.
Adjust position of sight tube in focuser in or out so the entire secondary can be seen. Check that the outside edge of the secondary is circular and concentric with end of the sight tube.
If not you will have to adjust the secondary's position using any or all of the adjustment screws available.

Step 2 : Align secondary to primary.

Remove the first piece of paper from step 1. Adjust tilt/rotation of secondary so that entire primary mirror can be seen. Again the sight tubes position in the focuser may need to be racked in or out. Look for the primarys mirror mount clips as a guide. You should be able to see all 3 (or 4) of them reflected in the secondary. Once you have this, align the sight tube crosshairs over the centre donut on the primary. Dont sweat if you cant get that last millimetre but get it close. The crosshairs may look fuzzy and hard to see. It can help to back your eye off from the peephole while keeping the crosshair centred.

Step 2: Align primary donut to the cheshire illuminated ring. This is the easy bit.

[Starkler (Geoff)]

Originally Posted by Legin

Also can anyone spot any obvious problems I should know about?

Thanks in advance

Rotation of the secondary is slightly out. I can see two of the primarys mirror clips but not the third. See step 2 in my post above.

Step 3 also needs to happen but you need some light shining into the side aperture of the cheshire to illuminate it.

[Legin (Nigel)]

Ok I have included a snapshot of my latest attempt.

I seem to be having the most difficulty aligning the secondary mirrior with the focus tube.

[Starkler (Geoff)]

Forget the laser!!

The cheshire is everything you need.

[wavelandscott (Scott)]

Originally Posted by Starkler

Forget the laser!!

The cheshire is everything you need.

For a beginner (especially) this is outstanding advice!!!

Too many people in my opinion rush out and get a laser expecting it to be the end all be all of collimation...they are not. A simple, no batteries needed, chesire is the right tool for the job.

[erick (Eric)]

Originally Posted by Legin

Something else I have come across my sight tube seems to be a Skywatcher version of a combined "Sight Tube" and "Cheshire" collimator. I didn't get any instructions with it so I am learning from scratch.

Here is a copy of the Orion Collimating Tool instructions - this might help.

[Jen]

Originally Posted by Kevnool

Have you given it a shot yet jen.........Cheer s Kev.

Yes i finally got it right thanks Kev
I found a lovely guy from this site that lives in the same town as me
We finally met 2 weeks ago and he helped me

[Kevnool (Kev)]

I hope Jen you watched the process and now your a champion collimator is it gunna be a call out again ( is that the same fella that lives 8 minues out of town on 60 acres of river front as i have read in another thread who offered accomodation for knowledge ?........cheers Kev.

[erick (Eric)]

Originally Posted by Kevnool

( is that the same fella that lives 8 minues out of town on 60 acres of river front as i have read in another thread who offered accomodation for knowledge ?........cheers Kev.

I think it is. Very tempting - maybe we'll descend on Swan Hill one day!

[Kevnool (Kev)]

One day i will possibly after observing with the oasis stargazers in Mildura in november