RC Collimation

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DMouse Canada
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RC Collimation

#1

Post by DMouse »


Hi, just got my first RC scope, 12 inch f8 truss tube. Anyway I already have a Hotech SCT collimator which I used on the EDGE110HD scope I had. The question is, is the procedure the same apart from removing the secondary (would never do that with an RC, right?) and is there anything else different that need to be done?

I collimated the scope last night but it might not be clear for a while so cant do a star test. Visually through the focuser it looks very good.

Any hints and tips greatly appreciated!!

Thanks

Paul
Website https://astro.bambury.ca Scope: Takahashi FSQ106DX4, Teleskop Service 12 inch Truss Tube RC -- Mount: Bisque PMX+ -- Camera: QHY268 mono, ATIK383L+ mono, SBIG STi, ZWO120mm-s, ZWO178MC
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Re: RC Collimation

#2

Post by UlteriorModem »


I collimate mine with a Howie Glatter laser focuser in the eyepiece holder. I look down the objective to where I can see the 'return' dot and center it with the secondary first then fine tune the main mirror.

But by far the best 'tool' is a star test. It might take a little guess work at first but a good star test and adjustment is the most accurate way.

You might even consider getting an artificial star. I have one but have a problem with not being able to get it far enough away from the scope to use it.

Here is a series of videos that may or may not help.

Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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yobbo89 Australia
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Re: RC Collimation

#3

Post by yobbo89 »


I would assume that a sct and rc are collimated the same with the hotech and its purpose is to remove image/focal tilt with getting the primary aligned to the focuser or if you are using a sct then the focuser if collimatible to be aligned to the primary which might be more ideal then just doing a star collimation.
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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Re: RC Collimation

#4

Post by yobbo89 »


UlteriorModem wrote: Tue Oct 15, 2019 3:13 pm I collimate mine with a Howie Glatter laser focuser in the eyepiece holder. I look down the objective to where I can see the 'return' dot and center it with the secondary first then fine tune the main mirror.

But by far the best 'tool' is a star test. It might take a little guess work at first but a good star test and adjustment is the most accurate way.

You might even consider getting an artificial star. I have one but have a problem with not being able to get it far enough away from the scope to use it.

Here is a series of videos that may or may not help.

Now Tom, since you have a howie, do you have any of the addons for it? My retailer sells howies but with no addons, they do have a Barlow for it, woundering if it's worth getting a howie and finding the ring holographic addon overseas so I can use it to collimated my focuser onto the secondary of my sct.
scopes :gso/bintel f4 12"truss tube, bresser messier ar127s /skywatcher 10'' dob,meade 12'' f10 lx200 sct
cameras : asi 1600mm-c/asi1600mm-c,asi120mc,prostar lp guidecam, nikkon d60, sony a7,asi 290 mm
mounts : eq6 pro/eq8/mesu 200 v2
filters : 2'' astronomik lp/badder lrgb h-a,sII,oIII,h-b,Baader Solar Continuum, chroma 3nm ha,sii,oiii,nii,rgb,lowglow,uv/ir,Thousand Oaks Solar Filter,1.25'' #47 violet,pro planet 742 ir,pro planet 807 ir,pro planet 642 bp ir.
extras : skywatcher f4 aplanatic cc, Baader MPCC MKIII Coma Corrector,Orion Field Flattener,zwo 1.25''adc.starlight maxi 2" 9x filter wheel,tele vue 2x barlow .

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Re: RC Collimation

#5

Post by UlteriorModem »


Nope, first of all they lasers themselves are very hard to come by as they are in quite limited production.

The 'holographic' grid gizmo is no longer made by them and is NOT available that I am aware of. Maybe there is a 3rd party overseas making them but I was un-able to locate them.

So for now the Glatter is for getting into the ball park. The rest I do with a star test.

The good news is that once collimated it stays there. At least on my Orion Branded 10" RC the locking screws on the main mirror work quite well. I haven't fussed with collimation in over a year! Then again I don't take the scope down very often so it does not get bumped around.

One more thing I forgot to mention. A tilt ring is almost mandatory. The OP's scope may well have one built in, also I have seen some of the newer ASI cameras have tilt rings built into them! I had to buy one for my 10" and it was not cheap! Also had to wait 3 months for them to become available!

Note some of the availability issues may have been resolved since Moonlite took them over. It's been a few years.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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DMouse Canada
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Re: RC Collimation

#6

Post by DMouse »


Thanks for all the info guys.
Well I have now noticed the secondary is no longer central. To adjust I believe that I should not loosen the middle bolt, just the three collimation bolts as spacing is critical, yes?
Website https://astro.bambury.ca Scope: Takahashi FSQ106DX4, Teleskop Service 12 inch Truss Tube RC -- Mount: Bisque PMX+ -- Camera: QHY268 mono, ATIK383L+ mono, SBIG STi, ZWO120mm-s, ZWO178MC
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Re: RC Collimation

#7

Post by UlteriorModem »


No you should not have to loosen the central screw. The procedure is to loosen one screw like 1/8th of a turn then snug the other two down. Also when adjusting the primary it REALLY helps to have a second person. I get my wife to turn the screws while I peer down the OTA and watch the results. The other 'best' way would be to prop up a mirror or something so you can see what is happening. Otherwise you have to turn the screw(s) walk around to the front "Opps wrong way" walk to the back, rinse repeat ad nauseum. Its much easier to tell your helper "Wrong way, go back" ;)

The central screw has a spring on it to try to keep the secondary in place. The spacing is not actually 'critical' as you will compensate for it with the focuser. Still you dont want it smashed all the way down compressing the spring.
Tom

Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
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Re: RC Collimation - Update

#8

Post by DMouse »


Update - well I got my Howie Glatter laser collimator, and the square grid hologram attachment. This thing is awesome!! Aligning the mirrors was a breeze and confirming it with a star test looked awesome. Now to book some clear nights so I can get some pics :)

Clear Skies

Paul


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Website https://astro.bambury.ca Scope: Takahashi FSQ106DX4, Teleskop Service 12 inch Truss Tube RC -- Mount: Bisque PMX+ -- Camera: QHY268 mono, ATIK383L+ mono, SBIG STi, ZWO120mm-s, ZWO178MC
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