Collimating a Skymax 127 Mak.

[JamesF]

Looks good James. ....is there no alternative available in this country?

Not that I am aware of, but I didn't look very hard.  Getting mine was no big deal though, and I think others have bought them too.

James

[Smithfire]

Good work. Thats about 20 quid then?.....how long did it take to get to you?

Clive

[JamesF]

Good work. Thats about 20 quid then?.....how long did it take to get to you?

Clive

I'm afraid I can't recall exactly.  Not too for me to get in a panic about, certainly  Someone else might have a better memory than me if you post a specific question about it?

James

[lensman57]

Looks good James. ....is there no alternative available in this country?

 Pico

Clive

There is a Rigel PicoStar, it is about £45.00. Pretty well made though.

A.G

[recceranger]

Clive,

You are the master Jedi and if my mak every loses collimation again, send me your post could!

[Smithfire]

Ha Ha! I'm sure it won't come to that Rick!

Clive

[RikM]

Just to add to this thread rather than start a new one...

I bought a second hand Skymax 127 some years ago and was never really satisfied with the view. By checking the diffraction pattern it was clearly a little out but I didn't know how much this was affecting the view. I had always been reluctant to get the Allen keys out and have a go at it because most advice is "Don't touch ". My eldest Son likes looking at planets and the moon occasionally and is happy with it, so I gave it to him. It only cost £80 so not too fussed about selling it and in truth, I didn't want to pass on a 'dud' to someone else.

Now, having read this thread and seen James's results after tinkering with his I thought why not...how hard can it be?

So a couple of days ago, with it properly cooled, I checked the star test diffraction pattern with a 10mm Pentax XW giving me 150x (more than the minimum 25x per inch) and ordinarily as high as I would go as it turns to mush at anything higher. Sure enough, it was offset by about 25%. While the pattern was clearly different intra and extra focus, the degree and orientation of eccentricity was consistent. I had read the Orion PDF to get an understanding of how the collimation bolts should work (but not clearly enough!) With the scope nice and cool, I didn't want to bring it into the house to look at mirror reflections, so I picked a bolt to start with and twiddled. Large bolt clockwise, adjacent small bolts anticlockwise, opposite small bolt anticlockwise (error!), adjacent large bolts clockwise (error!). I could see a very small change in the orientation of eccentricity but essentially nothing had happened   Thinking about it again, I realised that the way I had been adjusting the bolts meant I had moved the mirror either in or out but I couldn't have tilted it but I was sure I had read the PDF correctly, so thought I would bring the scope inside and follow the instructions properly using the reflections ect. just in case it worked in a strange way.

After removing the diagonal and sticking a coli cap straight on the back of the scope, I could see that the reflections were offset, similar to the diagram in the PDF but nothing like as severe as the 'out of collimation' image. Having read through again under the kitchen lights, rather than by dim red torch-light, I could see my error in adjusting the bolts   So I set about adjusting them the right way "Large bolt clockwise, adjacent small bolts anticlockwise, opposite small bolt clockwise, adjacent large bolts anticlockwise." until the mirrors looked concentric as seen through the back of the scope. Looking from the front of the scope however, they didn't really look concentric but it was too late and cloudy to let the scope cool again for another star test.

Fast forward to last night...

Time for a retest. Feeling confident I stuck my 5mm XW in, centred on Procyon and low and behold...it was worse than before. I pointed scope at the moon, mushy mess  Being a stubborn so and so, and now armed with a new understanding of how bolts work     start test tweaking began! Pick a bolt: CW, CCW; CW, CCW -> worse. Just like with a Newt then, you always turn it the wrong way first! Put it back and then go the other way. Now it starts to look better. Another couple of rounds of adjustment brings it almost concentric, but it is still just a little high, so I choose another bolt to start from Will this undo the work I have just done? 

No it didn't; I guessed on the right bolt   I had, to my eyes, essentially perfect diffraction rings both inside and outside of focus and for the first time with this scope, proper Airy rings when focussed. Pointing at the moon I saw the best sharpness and contrast (in the few obliquely illuminated craters at the limb) that I have ever had. I could also now see that the seeing was not bad but less than perfect! Time to swing the scope about a bit. Algeiba, Cor Caroli, and Castor all split nicely and cleanly but it does look odd, seeing actually quite bright diffraction rings round things at focus. On to Jupiter before it hides behind the house. Four moons, pin sharp. The two main belts and some disk shading were clearly visible and reasonable contrast but less detail than I get with my 10" Newtonian. To be honest I was fairly disappointed until I realised, I still hadn't switched EP's. I was seeing some level of detail on Jupiter in so-so seeing at 300x in a 5" scope that I didn't like

The message I wanted to get across is that if you know 100% that the collimation is out, don't be afraid to give it a go so long as you understand how the adjustment bolts work and you don't try and force anything that doesn't want to move.

I might even start liking this Skymax. I wonder if Alex will let me have it back?

[JamesF]

Very pleased to hear that you were successful, Rik.  I think your post underlines the fact that one must be patient and methodical about the process, but otherwise it's far from impossible to achieve good results without needing the services of a specialist.

James

[StarryEyed]

now you need to tweak it in focus and get that ball dead centre. if you have a Barlow use it with your 10mm on a bright star in goid seeing.

[recceranger]

All good there. I'm afraid I just couldn't get it with my 180. Had a right headache so specialist it was. Must say though, I'm 45 quid lighter!

[StarryEyed]

You should learn its can make the difference on a night when it matters. I will always remember a view on the lunar alpine valley through my 127 at three in the morning I always kept the scope as tuned as I could and this one night even having owned the scope for three years the view just blew me away that one morning more than ten years ago is still a vivid memory. I realise now that my Mak could not have given me a better view for the want of trying and I had great satisfaction from that fact.

Its worth the effort even if it to remove any doubt that you could not get anymore from your scope. I sold the Mak and bought a 80mm WO but often wished I had kept the Mak. The refractor objective has in ten years never needed adjusting which is more than can be said for its focuser which seems to be as rigid as a stack of ill fitting plants pots. Get everything nice and square and tight and then there is no traction in the Crayford which compared to a little mirror shift is easier to live with I think.

I might be talking myself into getting another Mak here......