Maksutov Collimation Question

[Astro_Baby]

Sooooooo.... Maksutovs should not be messed with by anyone outside an optical lab. - Discuss......

I want to take my Skymax 180 to bits to add a few mods (maybe) like an inbuilt cooling system, flocking, fix some aspects which will irritate me. To pull some tech upgrades out of the hat though the scope would need to be stripped down a wee bit and collimation of these things gives me the heebies ( and the jeebies and the wibbles and the wobbles too)

I did a fair bit of reading up and opnioin seems very divided with some people saying 'dont touch that dial - you'll be sorry' and otheres saying 'oh tosh - get in there woman and fix that thang'.

I am aware of some of the issues with Maks based on my reading but very (very very very very very) far from really knowing if what I am reading is right.

If collimation really is going to be a pig of a job I'd rather leave well alone with this one.

So whats the expert opinion on the board got to say on this ?

[GazOC]

I've stripped a Skywatcher 127mm Mak and got it back together and in collimation OK. Theres nothing THAT difficult about it but how the focuser worked (and how to access it) took a little head scratching IIRC.

[Peter Drew]

Hello A-B. I was a professional Maksutov specialist for 35 years so am familiar with the issues. Having said that, pretty much all of the scopes were of my own manufacture so I can't claim to be an expert on all types. What I would say is that without an optical bench collimator it can be quite fiddly and some designs are more sensitive to collimation. Because of this, some manufactures rely on accurate machining to align the optics with no provision for future adjustment, if you dismantle one of these then make sure to identify the orientation of each optical component.

[A McEwan]

Well, I've had two 127 Maks. I read the instructions on how to collimate, and could just about manage it with the first, but couldn't manage it with the second. In the end I sent it to Green Witch for collimation and it came back far better than I think I could have ever achieved!

Theoretically, it should be straightforward (if not easy) to dissassemble and reassemble, but in looking at my 180, I'd be reluctant to do it myself to be honest, though I have completely stripped down and rebuilt a Dobsonian, down to he very last screw!

So in short, I'm going to sit on the fence. It's nice and high and gives me a great view of the goings-on. Bit sore after a while, but I can always move around every now and then.

Good luck, and if you go for it, I'm sure your technical know-how will tame the beast and get it how you want it.

Then you can do mine...

Ant

[TheThing]

Perhaps you can have a go knowing that you can send off somewhere if it proves too difficult to put back together (but surely, nothing is too difficult for A_B?!?)

I assume that a Mak can be collimated even if it's in bits to start with?

[Astro_Baby]

Everything is difficult for me in truth I'd rather watch the telly at the moment as I am a bit burnt out.

As soon as I get to give the 180 a real run (assuming its does the business) I might well strip it down to install a cooling fan in the hope of reducing its cool down time.

[Duke2k]

I have just purchased a second hand Skymax 150 pro.

The collimation was slightly out and trying to view anything at above 120x was hopeless. After reading several comments on this on various forums I contacted Green Witch and was told that although they could collimate it, that it was very easy to do myself by viewing a third magnitude star, defocussing the image and then adjusting the three allen screws on the back to give concentric rings. The small 2.5mm allen screws are the locking screws so first loosen them. Then using a 4mm key slowly adjust the large screws untill the diffraction rings are concentrically placed. Adjusting a tiny amount at a time makes things easier as you can see if what you are doing is improving things. once you are happy with everything, re tighten the small screws and you're done. Collimating mine took around 30 mins and has made a world of difference!

[Carbon Brush]

Another fence sitter here (ouch).

I have collimated my MN78 MakNewt without problem. There are 'conventional' collimation arrangements on the primary and secondary. The corrector plate being fixed. So it was no more bother than an ordinary newt.

Instead of fitting a fan, can't you just leave the scope outside for a bit? Daft question?

[JamesF]

Can't speak for the bigger Skywatcher Maks, but I recently stripped and rebuilt my 127 because the mirror was both filthy and wobbly and the baffle tube wasn't perfectly straight, though the latter may have been self-inflicted when I removed the 2" SCT adapter that was fitted to it when I bought it (more like welded to it). I started from the position of zero knowledge whatsoever about what was inside and how it worked.

Once cleaned and reassembled I collimated it by eye with a home-bodged colli-cap. It was somewhat tedious, required a fair bit of calm and patience, but having done it entire on my desk and without the benefit of even an artificial star, I ended up with a diffraction pattern like this:

and decided I could live with that. In fact, mostly I sat about a metre in front of the scope with my eye as central to the optical axis as I could manage and worked out what I needed to do with the backplane to get all the circular reflections that I could see to be concentric. I've not touched the collimation since, and recently took this set of images of Mars using an SPC900:

I'm pretty pleased with those and feel like I made a fairly good fist of the job. The mirror does still wobble, but at least now it is predictably wobbly (it only shifts when changing the direction of travel of the focuser).

From the articles I've read on your site I'm certain you're no less competent than I am, so if your 180 is no more complex inside than mine I can't imagine you'll find much to worry about. I won't deny that I had an "oh dear, what have I done?" moment when I first reassembled it and saw how far out the collimation was, but it wasn't *really* all that bad.

Handy tip: the mirror assembly *will* fall off the end of the baffle tube if you tip it up after releasing the focuser mechanism. So don't

James

[jgs001]

I have collimated a Skymax 102... wasn't hard... but I think Mel has probably managed it by now, as this thread was originally posted in 2010 ...

[JamesF]

Bah. I hate it when people resurrect old threads...

James