SW 190-MN Collimation help!

[Gunnar]

Hello.

I started to read and understand more about how the optic really works in a newton. One thing that i first was so confused about is why the secondary mirror in some scopes has to be positioned a bit off-set (diagonal off-set) from the mechanical centre of the tube-centre and the focuser. But i think I start to get a hang of it now.

Anyway, my scope is a brand new Skywatcher 190-MN and I decided to collimate the scope with a laser collimator and the laser is now spot on but the mirror clips still isn`t symmetrical visible.

What to do next? Is it the standard crayford focuser who is not centered over the secondary mirror properly? I really need some advice here as i am a beginner of astronomy and this is my wery first scope!

And shouldn`t the secondary mirror have a diagonal off set towards the primary mirror?

I took this photo which i shot thru the 2 mm hole in my collimation cap, it`s a little bit dark but i hope it is useful anyway. see attached photo.

Regards

Gunnar

[Bazzaar]

Looks good to me, stop worrying!

Barry

[Moonshane]

to me it looks OK but you could tweak the secondary a little so the primary clips are more centred in the secondary reflection - see the left pic. you'd then of course need to re-adjust the primary after doing this.

secondary offset is more usual I think in faster newts so yours being f7.5 will probably not have much or any offset.

collimation can drive you a bit mad sometimes but you are not far away.

[Gunnar]

Hi moonshane.

It`s a F/5.3 The secondary does have a little offset (away!) from the primary mirror and the primary reflection is nearly at the edge of the secondary as i see it. Isn`t it so that i must move the crayford focuser in a direction away from the primary, so that the secondary will be centered under the focuser at least?

[Nova]

looks good to me too. remember that a laser collimator can show as correct even if the secondary is off. best to align the secondary using a collimating cap the secondary should appear as a circle when you look down the focus tube then use the laser for your primary. its easy to get hung up on collimation and worry that your not getting the best out of your scope but do a star test. if the results are good and your happy but the mirrors look a little off dont worry about it

[Gunnar]

Ok thanks!

Actually I did get out last night when it was as darkest in the night looking at the sky abowe, trying to see any star. Typicaly it is still allmost daylight whole night here and i couldn`t see any star. An artificial star must be the perfect tool some times now i have to wait until I can do a startest again.

Gunnar