Chesire or laser?

[Rustmonkey]

Just watched "Astronomysheds" tutorials on collimation and they were very good but which is best for my scope (SW150PL) which is 1200mm?

Also, trying to find an Antares collimator seems difficult in the UK. any links to a reputable dealer would be appreciated.

[x6gas]

My personal opinion, but neither!

Just use a colli cap (make one from one of the Astroengineering Posh dust caps for a couple of quid). I really think that's all you need for a scope like yours. Collimation really isn't that much of a black art once you've done it a few times...

[Rustmonkey]

I actually made one out of the dust cap that came with it using a red hot needle. it worked ok but thought that would just be a quick fix.

[Zachariah]

I have a laser and their a nightmare! Slightest movement in the focuser and itd miles off. Use a cheshire or a cap.

[Rustmonkey]

thanks peeps

[acey]

I agree, colli cap, it's all I used on my 8" for years and it worked fine. Only needed to re-collimate once in a while, mainly if I took the mirrors out for cleaning or did other DIY on the scope that moved the optics unduly.

[Thirdway]

You get a dust cap for the focuser. Turn it on its back and it should have four little extrusion marks on it. Scribe across the centre of opposite marks to find the centre, then drill through, or punch though with a small round tack nail.

Then get a Cheshire for final set up of the primary.

Just been through all that and it's fresh in my mind.

[Damo636]

Antares Laser Collimator. New & Improved Version | Telescope Accessories | Rother Valley Optics

[umadog]

A collimation cap with a silvered inner surface is a Cheshire. They're exactly the same thing. On its own it is not sufficient since its only designed to help you correct the tilt of the primary mirror. At a pinch it can also do a credible job of centring and rounding the secondary. A sight-tube (which is found on the common Cheshire/sight-tube combination tools) will do a better job of this, however. In addition the cross-hairs on the sight tube allow you to set the secondary tilt. Without the cross hairs you're left with having to judge whether the primary mirror's reflection is concentric with the edge of the secondary. This is may well be less accurate (because now the accuracy of secondary tilt alignment is constrained by the accuracy of the secondary positioning. Errors will add.) and is impossible in scopes where the secondary mirror is too small (a common problem, it seems).

[Mark Scott]

Well I have both (laser & Col cap) and if I'm honest I only use the laser.

All the best,

Mark

[paul schofield]

Gotta be the Cheshire for me. But then again I am just learning to collimate myself. Have learned lots from the answers to this thread. And I think Having to collimate a laser too, for me would just be too much, then I am a total beginner. Good luck.

[Parus major]

If you want any degree of accuracy then a basic Cheshire will do. As documented, unless you're paying £100 your laser will be out of whack and you'll spend ages swearing while trying to fix it.

[Digz]

All great advice above, Ill just add a couple more notes.

Lasers can be great but they come with their own issues:

1. They must be collimate themselves, yep thats right a laser collimator must be collimated. This is to ensure the laser is dead centre.

2. The laser must be inserted into the draw tube dead centre and not pinched to one side as this will throw out your collimation.

There is a technique called barlow laser collimation (or something along those lines) which IIRC gets over the issue of a badly collimated laser - google it or search for it hear and check it out.

HTH

[Tinker1947]

i would say the Cheshire, its accurate not to expensive and no batteries..

First Light Optics - Cheshire Collimating Eyepiece

[umadog]

The barlowed laser projects the center spot back onto the focuser rather than using the laser's return beam. This is more accurate because it doesn't require the laser to be accurately collimated. This is a particular issue with the return beam, since the return beam is twice the length of the outgoing beam. Furthermore, you're using the return beam to adjust the primary tilt which is an adjustment that has tight tolerances.

The outgoing beam is use to adjust secondary tilt and cannot be barlowed. As a consequence, you still need the laser to be collimated. The secondary tilt adjustment is less strict tollerences, however.

[Thirdway]

I don't have a laser, bit the advantage is that you can adjust the primary without going back to the eye piece. That said, if the primary needs adjusting, turn one of the adjusting screws half a turn then check. If its going the wrong way then turn it in the opposite direction. Doesn't take long.