Collimation question

[lulaz]

I bought the SkyWatcher 6" dob. and I got the manual...

Well, the manual teaches how to collimate the telescope. Well, I've seen the Astro Baby's guide to collimate, and it is a little bit more complicated, so I was wondering... Which of them should I use? the Astro Baby's or the manual? I mean, will the manual give me 100% collimated telescope?

Thanks!

[lulaz]

anyone?

[brantuk]

I find the Skywatcher manuals give a general guide to collimation because they give you the basic principles only. They are pretty generic but if you follow the instructions then you will be very near.

Astro babys guid gives a lot more detail as to why and how you should do collimation. It is a bit like a fine tuning manual to get the very best from collimation that you can. Hope that helps

[cyborg421]

Try this site

Collimating a Newtonian

Simon

[sixela]

HEALTH WARNING:

the video referenced above makes you believe that you can centre everything.

You can't: the silhouette of the secondary's reflection will not appear concentric with the rest, but offset towards the primary. That's normal and should not be "fixed", and it is a physical impossibilty to completely centre that without making something else uncentred, unless the f/ratio of the telescope is infinite.

On an f/8 scope things will appear close to what the video shows, but trying to get everything centred on an f/5 scope will make you mad.

[france79uk]

Thats interesting, I am a newbie and having problems getting it all squared up, ie when all else is central, one side of the focusing tube appears thicker than the other, wonder if thats the cause of my recently acquired Tal 2 not performing any better than my Tal 1, ie slightly blurred images and not so sharp as the Tal 1 at same mag.? good video link though, thanks.

paul

[sixela]

Thats interesting, I am a newbie and having problems getting it all squared up, ie when all else is central, one side of the focusing tube appears thicker than the other,

If you havfe a centred pupil by definition the direct view of the focuser tube is concentric. If you're talking about the reflections, you see only the reflection of the focuser tube and if everything's collimated well you actually see it face on (i.e. only the end), so it shouldn't be "thicker" anywhere.

What does happen is that *around* that focuser tube reflection, Cheshire ring within it etc., the silhouette of the secondary's reflection isn't concentric; that may be what you describe, and see the health warning above (that is normal).