Argh! Collimating secondary mirror!

[Amra]

Just need to vent for a second, wish I never touched the secondary mirror!

I think I even misunderstood what a misaligned mirror looked like and may have moved a perfectly aligned mirror, but I don't remember what it looked like initially anymore!

Been fiddling and adjusting for hours to get it perfectly centered under the focuser, but no success yet! Have read numerous threads & guides and will attack the problem again tomorrow with replenished energy! 'Fortunately' I haven't had clear skies, so I'm not missing out on anything - just want the collimation to be extremely good for when my camera arrives.

[Daniel-K]

By a Cheshire collimator From Flow to help alignment

[Amra]

I'm going to order one! I find it hard to get the exact central position/shape to the focuser, even when looking through a collimator cap. I think the chesire collimator would help greatly. To get my secondary mirror back to 'default' position maybe I could move the secondary back to the opening of the tube with the adjustment screw, put them all in their initial positions and then afterwards start aligning the secondary forward into the tube.

Tomorrow I'll cycle through astro baby's instructions again & again and hopefully get somewhere.

[rwilkey]

The secondary mirror just needs to look like a perfect round shape down the focuser, as long as you have got that to start with before you collimate the primary mirror you will be OK. Also, another rule about collimation, if it ain't broke, don't fix it. In other words, don't collimate for the sake of it.

[cantab]

If the adjustment screws are making the secondary shift erratically, try slipping a milk bottle washer between them and where they bear against.

[Astrosurf]

The secondary mirror in fast F5 scopes like yours have a slightly oval appearance. See Astrobaby's guide: www.astro-baby.com/collimation/astro%20babys%20collimation%20guide.htm

Alexxx

[MadAlbert]

Good advice checking out AstroBaby's instructions.

Just remember, the secondary obstruction needs to centered in the aperture then you must see all the primary (i.e. centered in the view) in the secondary to be able to complete the process.

I you don't do the first bits you will end up chasing your tail.

[Astrosurf]

Have you also seen the Orion Optics YouTube collimation video? It's the one I used. I can't get YouTube at work to give you a link! Do a Google search. It's the dark-haired Amercian guy!

[Amra]

I've done some more adjusting now on everything - firstly I think my centering of the secondary mirror now is very much spot on and I think I see the offset collimation pattern Astrobaby mentions for the collimation pattern on fast scopes - the crosshairs are not completely lined up to the center of the primary and my eyes don't end up in the center circle either, but offset a little bit to the left, is this the optical illusion as I understood it?

I've used my laser collimator (which I've confirmed to be collimated) but I can't for the life of me get it to hit the exact center of the primary mirror, it's very close, 1cm to few millimetres of, this should be a sure sign it's still not optimal right?

I also tried putting the laser into a barlow, rotating it around in the focuser and with a sheet of paper infront of the tube I can see laser light hitting it, if I don't barlow the laser no laser light escapes the tube when I rotate it.

The laser wobbles a tiny bit in the focuser, much to my annoyance, so I'm going to try the Cheshire later on and trust what my eyes see rather than what that laser tells me.

[ronl]

http://www.andysshotglass.com/Collimating.html I think this is the link you need just copy and paste it

[ronl]

http://www.andysshotglass.com/Collimating.html I think this is the link you need

[ronl]

Sorry you don't need to copy and past it just click on the link (silly me)

[Amra]

I tried everything and got decent results inside today, also feel much more comfortable tweaking stuff already. Tonight there were good seeing conditions so I put up everything outside, checked collimation with the laser, and it was still a wee bit off. So in complete darkness I collimated with the laser and got something I estimated to be a good result, when I re-checked everything inside everything was surprisingly well aligned. Lasers aren't that bad after all! I star tested I think it was good, but it will be easy to judge on images if something is off I suppose.