Altair 200 Collimation

[Astrosurf]

I’ve recently got an Altair 200 Newt but the huge collimation bolts are confusing me. I can manage to collimate my SW 200P no problem but these bolts are new to me. There are the plain bolts with the white knobs and the black bolts that have springs. 
 

Do I loosen the black bolts and tighten the whites to adjust or vice versa? When I get the donut in the centre, some of the bots are still a tiny bit loose. So when I tighten them up the donut moves. It’s doing my head in. 
 

Alex

[John]

The black ones with springs adjust the tilt of the primary. The white ones are locking ones and should be loosened before adjusting the black ones and then just lightly tightened down once collimation of the primary is achieved. The cell looks like a GSO made one so it will be the same as the Stella equivalent.

The mirror cell in these scopes is made of quite thin metal so tightening the white ones too much actually warps it a little, affecting the collimation. Just lightly snugged up against the cell is what is needed for the white ones.

Edited May 8 by John

[Astrosurf]

Thank you. I never know how tight is tight. Just to the point the bolts stop turning?

Can you also over-tighten the black ones? It's hard to tell as they're springy.

Edited May 8 by Astrosurf

[John]

1 minute ago, Astrosurf said:

Thank you. I never know how tight is tight. Just to the point the bolts stop turning?

The point of them is to stop the mirror cell moving so just gently pressing against it.

Some folks don't use locking screws unless the scope is being transported. The springs on the tilt adjustment ones should be strong enough to hold the cell in the correct position during normal use. I say "should" but in the 10 and 12 inch sizes the GSO springs are notoriously weak and are usually promptly upgraded by owners. I'm not sure this is the case with the 8 inch apertures ones though 🤔

 

[Astrosurf]

I wish I could be shown. It's just all too subtle to understand in text. So some people don't have the white bolts at all? 

It's interesting that my simple SW 200P rarely went out of collimation and I traveled with it all the time. It has little Allen key sockets and small screws. These Altair ones seem like serious overkill.

[John]

19 minutes ago, Astrosurf said:

... So some people don't have the white bolts at all? 

 

They have the white bolts but they don't use them - they leave them loose. I used to do that with my Orion Optics newt, unless I was taking it somewhere in the car.

Often locking bolts are a different size (smaller usually) than the collimation bolts but GSO have chosen the colour scheme and sizes you have. This is the back end of the Stellalyra 8" F/4:

 

Edited May 8 by John

[Astrosurf]

Thank you. I'll try collimating again and see how the stars look. I'm kind of thinking of selling the scope due to all the collimation difficulties it's giving me. Plus I often catch the bolts when I'm carrying it. I'm quite clumsy. I never had to worry about that with the Skywatcher.

[John]

The old GSO 8 inch newtonians used to get criticised for having small and fiddly collimation and locking bolts which needed different tools for the different screw heads. I guess they responded to that with the larger, "no tool" bolts that are fitted today.

At the end of the day though, they are just bolts, so I guess they could be replaced with something with a lower profile 🤔

 

 

[Spile]

I tighten the locking bolts gradually and sequentially to ensure the “final turn” doesn’t change the primary alignment.

[AstroMuni]

On 08/05/2024 at 21:42, Astrosurf said:

Plus I often catch the bolts when I'm carrying it. I'm quite clumsy.

Attaching a shower cap or similar might help. I have a cloth bag on my 130pds.

[Astrosurf]

On 08/05/2024 at 19:34, Astrosurf said:

I’ve recently got an Altair 200 Newt but the huge collimation bolts are confusing me. I can manage to collimate my SW 200P no problem but these bolts are new to me. There are the plain bolts with the white knobs and the black bolts that have springs. 
 

Do I loosen the black bolts and tighten the whites to adjust or vice versa? When I get the donut in the centre, some of the bots are still a tiny bit loose. So when I tighten them up the donut moves. It’s doing my head in. 
 

Alex

I’ve been trying again but with the locking bolts loose. I get so close but the donut just travels around to the right of the centre dot. The black bolts are getting shorter and shorter. Should they be longer?  It’s maddening! Any idea what’s happening? The bad drawing will hopefully illustrate what I’m seeing. Thanks, Alex

[Astrosurf]

I did it! It was the secondary that needed adjusting 😊