Collimation of 10N

[pesa]

I've been zooming in on forum users images taken with 10N/12N.

All of you have better collimation than me.

 

Do you get that good collimation only with glatter and eventually tublug?

 

Sofar I've recentered center marking (was 1.5mm off) I use a perfectly collimated glatter laser and tublug.EXTREMELY CAREFULLY)

I will also use catseye autocollimator soon.

 

I would appreciate any tips any of you can give me because I'm nearing desperation.

Mechanically I Think all is appropriately tight.

My collimation error is pretty much constant over whole sky and does not depend on mount-error (same error even with 0.5s)

 

Sharpness isnt spot on either  I know ( an 41cm RC at same location got seeing of ~1.5') that night.

 

Here is an example, pixelscale is 1.36'/pixel. ASA N10+atik460 bin1, 0.95 wynne

 

As you see there are 2 errors, all stars are drop formed and the big star at lower right has double diffractions from spider vanes (8).

 

Any  thought Before I give up and pay someone (anyone interested ? ) to travel here and collimate for me?

 

 

pelle

 

[pesa]

The big TIFF is actually a raw fits just saved as tiff. so no gamma. Why isnt fits allowed, would be more practical IMO.

[pesa]

Program thougt I still had 0.75 reducer, I forgot to change to 0.95 wynn. pixel scale is 1.04'/pixel. So fwhm shown in attachment is too pessimistic.

 

pelle

[ChristerS]

Hi,

 

I also have big problem get good collimation with the 12N tube, 0.73 and 0.95 corrector. Using Glatter laser (inkl. tublug), Infinity XLS and Telecat.

 

Now I have used up all the collimation tools, looks perfect through the InfinityXLS but still small elongated (egg shaped) stars. All collimation made at original focus distance using 3" extended tubes from ASA. And the extremely annoying glitch in the 2" focus holder where the Glatter laser and Inifinity is not fixed but move around, I DONT tighten the two lock screws instead push the tools with light force against the 2" focus opening, is this the way to do it? (Howie told me I should tighten the screws but I don’t agree, the laser dot then moves around depending which screed I tighten first).

 

I have read some of you make final collimation with stars, can someone explain the best way to do this?  Is it a trial and error process, change one of the main mirror screw a bit take an image inspect, move it again and so on.

 

On my LX200 I used the airy disk of a star in focus with high magnification and good seeing, what is the deal for the 12N tubes? 

It would be great if a collimation guide is presented here in the forum or at ASA website, If I get it right I will make a guide

 

Regards,

/Christer

[MarkS]

On my ASA10N I use the Glatter laser and Tublug for initial collimation and checking in the field after travelling. To fine tune I use the Cat's Eye InfinityXLK. I find the latter difficult to use but I think it can get closer than the Laser/Tublug - IF I have enough patience!

 

It is important not to rely on the holding screws on the OK3 2" adapter. I push the Laser firmly against the adapter, and very gently tighten the holding screws to stop slipping - almost no pressure on the screws. I never seem to have oval star problems at f/3.6......touch wood!

 

I would also like to know how people do a final collimation on stars.

 

Mark

[pesa]

Thanks Mark/Christer for your relies.

 

My trying fix ovals/drops turned out to be akin to stearing a car with the rear view mirror. The tube was astigmatic which led to ovals/drops of different orientation depending on which side of focus I was on. Even a small deviation from ideal focus resulted in ovals/drops. No wonder collimation couldnt fix my problem. 

Perhaps depending on non-ideal seeing (never below 1.5',often 2.5') and possibly astigmatism Sequence's AutoFocus doesnt work well. The Misfocus then resulting in oval stars.

ASA has taken back the tube for adjustment without fuss. Kudos for that!

Now I'm praying for a Quick return since theres really good weather now!

 

pelle

 

Edit: I use the latest beta of sequence, 208

Edited September 10, 2015 by pesa

[Corpze]

Good to hear you are making progress!

 

/Daniel

[ChristerS]

Hi,

 

Finally made progress regarding good collimation with the Glatter laser and tublug. One important issue is the glitch in the 2" focuser cylinder, the Glatter laser is NOT tight against the cylinder 2" wall and the laser dot dance around depending how I place it, the lock screws are not tighten. The solution was to use some scotch tape inside the 2” cylinder wall, this made the Glatter laser fit perfect with no glitch, the same goes for the tublub also fit like a glove

 

Second I use the tip from Jason in the link below to make a template for the tublug to make it easier to center the triangle around the hole in the tublug.

 

I like Pelle have presumed astigmatism in the system which have made the collimation effort hard and confusing, my ASA12N is shipping next week to ASA for service.
When the tube return I will give Catseye tools a go for final tuning. With the Reducer 0.73 the collimation is more demanding than ever, with a fully working 12N OTA I hope it will run smoothly. Looking forward to a fully working OTA

 

http://www.cloudynights.com/topic/319863-my-howie-glatter-laser-collimator-experience/?do=findComment&comment=4096883

 

BR,

/Christer

[Waldemar]

This kind of nosepiece would be the solution to center collimators: http://telescopes.net/store/tadt-2-2-inch-sca-t-adapter.htm 

Or a B aader clicklock maybe.

 

Regards,

Waldemar

[Waldemar]

Ok the link did not work. But I meant the  Hotech SCA Collimator. Google will help.

Edited September 13, 2015 by Waldemar