Collimation of the Mak 180 pro

[Neil H]

Collimation  of the skymax 180 Pro is it hard to do , I strip down my mak and flocked it , then after rebuild checked Collimation  , it was hard to find good info on how to do this ? I tried to Collimation like a newtonian how wrong was I made a real mess Jupiter at low mag was ok but high mag it was rubbish view like looking through soup . Had a chat with Grant at FLO he said make sure you keep star in the centre of the eyepiece so I did  and next star test was poor so what was I doing wrong ?

I messaged this great man called Peter Drew at last someone to explain how to Collimate it once I got my head in the right gear it was easy   

So this how to do it you defocused a star and see we're the obstruction is mine was off to one side as you adjust the Collimation screws the star moves in the eyepiece FOV you then recentre it and look at the obstruction is it better or worse keep adjusting till the obstruction is in the centre of the defocused star and then get a 5mm eyepiece or the highest you have and recheck it if its still centre your done 

So it's not as bad as I thought it would be to do I did do this in the day time with an artificial star with tracking on the mount turned off , that night I did a real star test  and good news it was spot on and the planet killer is up to speed again 

[wookie1965]

Nice one Neil now collimate my Tal

[M40]

Spot on Neil, takes a lot of the unknown out of it. Many thanks.

[bosun21]

You need to adjust both sets of screws to prevent any mirror shift while slewing the scope. Each pair are a push/pull arrangement.

[Neil H]

8 hours ago, wookie1965 said:

Nice one Neil now collimate my Tal

Paul you don't need me Peter Drew is near you lol

 

7 hours ago, bosun21 said:

You need to adjust both sets of screws to prevent any mirror shift while slewing the scope. Each pair are a push/pull arrangement.

Thanks bosun21 the thread on stripping the Mak was a great eye opener to how this works

[M40]

19 hours ago, bosun21 said:

You need to adjust both sets of screws to prevent any mirror shift while slewing the scope. Each pair are a push/pull arrangement.

Just to clarify, the collimation plate assembly that holds the primary mirror is adjusted by the three larger screws with the three smaller screws "pushing" against the collimation plate and locking it in place. To adjust, slightly slacken all three of the smaller screws before adjusting the larger screws. When tightening, expect things to move as any slack in the larger screw thread is taken up. Captain scarlets topic "reverse engineering the skymax" has a picture which shows the arrangement. 

[M40]

Neil H and myself have had a few chats about collimation of the skymax180 and whereas Neil could use an artificial star, that option wasn't available to me as you need a line of site of about 100 - 150 feet. So I bought the ocal 3. Note that from what I have read, the earlier versions of the ocal may not work due to the focal length of the 180.

Using the ocal is all about knowing what to align with what. In the skymax, the eyepiece is fixed, the meniscus is fixed and the secondary mirror is fixed. The only adjustable item is the primary mirror assembly. From captain scarlets topic it was found that the secondary baffle may be fitted in different positions, so although it is fixed, it should not be used for alignment.

The primary mirror assembly is basically the collimation plate, primary mirror and primary baffle and as the collimation screws are adjusted, the whole moves as one component. The focusing position of the primary mirror is not important.

When the ocal is clamped in position I found it could move off center, so with power connected and the picture on screen, I spun the ocal as I tightened it to ensure it remained central as far as possible.

This is what you see when using the ocal....

The eyepiece/ocal camera and egde of the telescope on the meniscus lens are all fixed so I aligned the edge of the telescope and the edge of the primary baffle

Note that the edge of the secondary baffle is not centered, so like captain scarlets it just seems to be plonked in roughly center.

The green circle being the edge of the primary baffle and the blue circle being the edge of the telescope on the meniscus.

So what was it like when I did a defocused star test? Using an 8mm eyepiece is was spot on, using a 5mm it was out so some tweaks later and it's sorted.

When you tweak it, slightly loosen all three of the smaller screws, adjust a larger screw, retighten the smaller screws to see how it has changed and repeat etc etc,

So the end result is if you have a clear line of site of about 100 to 150 feet, use an artificial star, flo do one at about £20, if you dont have that sort of space, the ocal 3 works. I will be trying it with a reducer to see if it works and if better focus is obtained. 

All the best and hope the topic helps someone in the future.