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Collimating a Skymax 127 Mak.

Smithfire

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StarryEyed

StarryEyed

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I used to culminate mine regularly. Use a bright star that will put lots of light into the diffraction pattern and its best done on a steady night. High power I used a 7.5mm and 2.5 power mate. its a bit tricky to get the order right for slacking off an adjustment. From memory the bigger screw locks the mirror cell and the smaller ones are used to make the adjustment. So for each adjustment you need to slacken off and adjust and then take up the adjustment on the other two adjustment sets of screws. Remember that you need to move the mirror as a whole so you have to balance the adjustments accordingly around the mirror so as not to create an optical pinch which will cause the detraction to take on a triangular form.

If you haven't done it before then try working with only one adjustment until you are comfortable with what is happening. Be warned that it can go way off and take quite some time to get it back it you make a mess of it. I never damaged mine and had it wonder all over the place when I first tried to it. remember to feel and think about the tension in the screws that you can sense in the alen key this is telling you about the amount of stress you are putting into the mirror. It might be a good idea to put some sticky labels on the scope and not your changes down on paper until you get used to it. try small adjustments not bigger than a quarter of a turn.

It is tricky but eventually when you get the feel for it you will be able to make adjustments with an almost in focus star image to completely nail it.

It is worth learning I ended up flocking mine which made a big difference but I never could have done that with out being colminate the scope.

Best read up as much as you can on the subject before hand get a good book.

When you nail it you will know!

Kevin.

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knobby

knobby

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I've often wondered about tweaking mine ... Each time I think about it I start to feel that if the adjustments are that fine and so critical then how much does it go out when the famous focus shift or mirror flop happens going from winding the focused in to winding out ?

Is it really worth it ?

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lensman57

lensman57

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Hi Guys 

Just wondered if anyone could give any do's and dont's about this procedure?. It deffo needs doing so I feel I should stop prevaricating and crack on.  

Any words of advice gratefully accepted

Clive

 Unless you have compelling evidence that it needs collimating I'd leave it alone.

Regards,

A.G

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recceranger

recceranger

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My friend, leave it well alone. I assumed my MAK 180 Pro was out and tried to adjust. Created a rod for my own back!

They are hard as granite to collimate and the possess will bring you to the hurt locker. I have since sent mine to Kay Optical Ltd to get it professionally done.

Your at the fork in the road with this mate. Ensure you are 100% certain that a it's out prior to committing!

Rick

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knobby

knobby

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My friend, leave it well alone. I assumed my MAK 180 Pro was out and tried to adjust. Created a rod for my own back!

They are hard as granite to collimate and the possess will bring you to the hurt locker. I have since sent mine to Kay Optical Ltd to get it professionally done.

Your at the fork in the road with this mate. Ensure you are 100% certain that a it's out prior to committing!

Rick

Sounds like the voice of experience there !

I'm sure I read somewhere that it's best to leave well alone unless you have plenty of time on your hands ...

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Smithfire

Smithfire

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I hear you guys, but looking down the front of the scope the ring pattern is definitely lop sided. I dont have the time or the money to drive it 100 miles to get it collimated professionally and there's no point mailing it. If I end up having to strip it then so be it. I am prepared for the consequences. I'll let you know either way.

Clive

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lensman57

lensman57

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I hear you guys, but looking down the front of the scope the ring pattern is definitely lop sided. I dont have the time or the money to drive it 100 miles to get it collimated professionally and there's no point mailing it. If I end up having to strip it then so be it. I am prepared for the consequences. I'll let you know either way.

Clive

Hi Clive,

I am a bit like yourself, once I get a bee in my bonnet I won't rest but before attempting to do this  at least do a proper  star test, that is all that matters. If the star test shows the rings to be lob sided then yes it needs collimating but if all you see is an anomaly due to bad seeing or atmospheric dispersion then no amount of collimatng is going to sort that one out. There is also a remote possibility that the focusing train might have dropped for some reason in which case the whole thing may have to be disassembled and put back again. Has the scope been dropped by any chance without you knowing?

Regards,

A.G

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recceranger

recceranger

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Clive,

I'm with you reference mailing concerns using postal couriers but remember how we get our telescopes in the first place! The majority get delivered via Royal Mail, Fedex and an insurmountable amount of other delivery services.

There are 2 companies that I have researched and they can correct collimation, Kay Optical Ltd and Astronomia in Surrey. However, it's swings and round about's. If you really know your business with the inner workings on the MAK then give it a lash, but be warned, I spent several hours over 3 nights armed with instructions for multiple techniques. I was chasing the outside of the envelope all over the place.

The problem is you will have to continually adjust your eye position (whether your looking in through the main objective lens from the front or via rear). Your point of view will change as a consequence every time you step back to adjust. In addition, don't believe what the manual or any down loaded instruction states, the smaller and larger bolts on the back send the mirror on a crazy Ivan every time you turn. You need to be a Jedi to keep track!

But this is just my experience. I would ask you to ensure the test star is bang on centre in your FoV as this can give a false read on the MAK. If this is all squared then have a crack and the very best of luck to you my friend.

Rick

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JamesF

JamesF

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I've completely stripped my 127 Mak, rebuilt and re-collimated it.  It's laborious, but all that's really required is patience and being methodical.

You can get a long way by setting it up on the mount indoors and arranging somehow that you can get your eye in line with the optical axis about 1.5m to 2m in front of the OTA.  Anything you can set up to make that position repeatable will help, even if it's resting your chin on a camera tripod head or something along those lines.  You can easily see if the OTA is out of collimation then because the reflections of the mirrors will appear to twist off in one direction or another.

Then it's just a case of using the screws to adjust the backplate to the correct angle.  Three screws press against an inner plate to push the backplate away from it (towards you as you stand behind the OTA) and three pull it away from you.  Obviously you have to loosen/tighten them in pairs as described in the document that knobby linked to.  Be methodical and return to check the view from the front after each change and you'll soon work out which screws move the mirrors closer to what you want or further away.  Make notes on which screws moving the back in or out have what effect on the view.

This is exactly the way I did mine, which was way off when I started because the baffle tube was clearly not even centred properly.  Then I did a star test.  This was the result when I put a camera in with the scope out of focus:

diff-rings2.png

It wasn't absolutely perfect, but pretty close and I decided I could be happy with that and probably wouldn't get any better without an artificial star to collimate against.  I've very recently bought an artificial star, but for Maks and SCTs I believe you really need a good fifteen to twenty metres between the star and the scope so it's not something you can do in a small space.

I don't think it's that much harder, if any, than collimating a newt from scratch (that is, starting by aligning the focuser and getting the secondary in the correct position as well as correctly tilted).  It can be frustrating until you get the hang of which screws do what and if you can't either walk away and come back when you've got your collimating head on or channel the frustration into a greater determination to get it right then perhaps it isn't something you should attempt.  It's a bit of a Zen thing, really :)

Now there's an idea.  I should write a book.  "Zen and the Art of Telescope Collimation" :D

James

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JamesF

JamesF

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Here's a picture of my Mak in pieces:

IMG_0068.jpg

The backplate with the baffle tube attached is on the far right.  At the bottom right is the plate that fits inside the tube that the collimation screws work with.  The cut-out is for the focuser, so I guess that means the first screw from the focuser clockwise is a "push" screw and the first one anti-clockwise is a "pull" screw.

James

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JamesF

JamesF

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I've not checked, to be honest.  It's an unpleasant amount of shift when you're imaging at an effective focal length of about 4.5m though :(  The focus is completely lost when change the direction of travel based on the view from the camera.

I'm really very attached to the little Mak though.  I'd only sell it to replace it with a less well-used one and I can't even see the point of that.  One day just for kicks I might try to make up a mirror carriage that runs on bearings, or work out some other method for moving the mirror so the shift doesn't happen.

James

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Smithfire

Smithfire

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Just an update. Managed to collimate the Mak last night. Took me 2 hours but it really wasn't that scary, just made small adjustments and observed the movement. It's a bit like patting your head and rubbing your stomach at the same time, just a knack. Concentration and time were the key. Got it pretty much there. Might do some more fine adjustment when I can buy or rig up an artificial star. Thanks for all the replies guys. ....really helpful.

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JamesF

JamesF

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I said it was laborious :D  Well done.

Some people make an artificial artificial star by gluing a ball bearing to a piece of card and either putting it in the Sun or shining a torch on it.  The reflection of the light can then be used as a "star".  Not much chance the former would work for long enough to collimate anything here at the moment :(

I just bought one of these: http://www.hubbleoptics.com/artificial-stars.html  For USD 24.95 including the shipping it seemed silly not to.

James

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