Question on collimation of Truss RC with TAK

[Flugel88 (Michael)]

Hello,
I've been playing with my new TAK collimation scope trying to learn the whole procedure using this article as a guide http://www.dosborne-astroimages.co.u...on_article.htm

I have managed to get the Secondary online was simple enough but moving on to next stage adjusting the primary and spiders i have noticed that my spiders are off line somewhat.
Indicated in Image A.

Looks like the spider veins are not lined up with H.
Is that something that i need to address?
I have misaligned the Primary tilt tip to allow for the spiders to be in viewed by doing so is that the cause of the spider vein misalignment?
Also i have noticed that once i center everything else there is no gap or light annulus I

I have included a image of the spiders and secondary mechanical setup for the RC Truss.



Waiting on a new focuser coming soon when released by customs.

so ill have to perform the whole process again once i have installed that.

[DJT (David)]

Originally Posted by Flugel88

...Also i have noticed that once i center everything else there is no gap or light annulus I

Hi

I found that with my RC 8 I needed all 3 of the extension tubes and the moonlight focuser fully racked out to be able to see the annulus at I using the Tak Scope

I don't have an issue with the spider so cant help with that

Enjoy the scope.

[glend (Glen)]

Number one rule in RC collimation is do not touch the primary unless absolutely necessary and then only after everything else is done. If you don't have one mirror as a reference point then all other steps can be out even if appearing correct. Suggest you watch Stephen Kirk's Utube videos on RC collimation (Three part) which shows what you can do without a TAK, and will get you very close. With the primary out of wack your going to need to go through some itterations to try to get it back. The Howie Glatter Concentric Ring attachment is a good way to fix the primary tilt, and you can also sort it out by removing the internal baffle tube and using Cheshire from the rear to line it all up. Good luck.

[Paul Haese]

Hi Michael,

well done on looking at collimation with a Tak scope. Ok first things first.

You will need to adjust the primary at some point. If you want perfect collimation you will note your primary will have moved during transit and you will need to adjust it.

Michael which scope do you have? Do you have the camera collimation ring? If so then I will go through the procedure.

Step 1.

Centre the ring marked B in your diagram over ring C using the secondary screws. The screws need to be snug but not too tight.

Step 2

Next more the primary. In your case right now you have to move the primary as shown by your first image. Ring E has to move until it is concentric with ring F. The small screws are the locking screws and large screw is the actual collimation screw. Again snug but not too tight is the order of the day with regard to the locking screws. Be mindful that when doing up the locking screws they can move collimation a bit.

Do the above steps until every ring inside ring F is concentric. You might need to do this several times to get it perfect. Be very fussy.

Now if you have the camera collimation ring on a 12" scope or on a 10" as an extra you can move all the rings inside F as one to make the F ring and all others concentric with the very outside aperture. Make sure you also look for the very tiny Tak rings inside ring A with a very small white dot in the centre of those rings. Once you see all those rings concentric and all other rings concentric you are truly collimated. If you get collimation that good you will not need to do a star test. The important part is looking for the little tak rings. You will need to hold the light source at exactly perpendicular to the white disk to see the rings properly. Just a tiny bit out will mean sacrificing a lot of sharp detail. These scopes are very finicky when it comes to collimation.

This whole procedure takes about 20 minutes to get 100% accurate.

Now importantly, do not bother doing this until you get your new focusor. It sags and that will affect your results. The focusor that comes with the scope is rubbish and will not hold collimation or anything else for that matter. However, it you just want to get some practice in, then just set the scope up on a table and just practice.

If you need to ask more questions please feel free to do so. BTW your rings image made my explanation so much easier.

[Logieberra (Logan)]

I always found this to be the best help for me in using the Tak colli scope on an RC:

http://rcopticalsystems.com/support/...imation_V3.wmv

[Flugel88 (Michael)]

Thanks everyone for your help and input i greatly appreciate it.

Hi

I found that with my RC 8 I needed all 3 of the extension tubes and the moonlight focuser fully racked out to be able to see the annulus at I using the Tak Scope

I don't have an issue with the spider so cant help with that

Enjoy the scope.

That makes sense to me David something i didn't think to try.

Paul I have a new GSO 14RC.
Would i require a collimation ring to get it all lined up with optical axis with the 14?

Took me a while to even work out the adjustment bolts for the primary not much info around the net for these scopes.

But i did read some posts you made regarding the importance of a TAK for the collimation procedure and now that i have played with it a little i understand why it is an absolute necessity for collimation..

The whole idea of making rings inside rings inside rings all perfectly concentric does sound a bit daunting. makes for a great challenge.

My new 2.5" focuser arrived today finally so when i get the time off work next week i will install that and attempt some real collimation.

I have read about the possible cascading downward spiral of misalignment that can occur when not being very careful with collimation as Glen has pointed out.
I hope i don't end up going down that path.

If you need to ask more questions please feel free to do so. BTW your rings image made my explanation so much easier. 16-09-2015 05:39 PM

I will probably be flooding the forum with questions in the near future as i am still a real newbie.
Glad the diagram helped would be a very difficult thing to describe with out it.

[DJT (David)]

Enjoy the scope. Currently on the wish list

[Paul Haese]

Michael. You got a nice scope. The 14 is probably more like what I would really like at present.

The 14 will come with the camera collimation ring standard. I was involved with this part of the design. So on the back of the scope there will be the primary collimation screws. Almost out as far as the truss support bolts. Then right in near where you thread the focusor on is the collimation ring and there are one big bolt with two smaller grubs either side of each other. Three in sets in total. Does that make sense? If not can you take a shot of the back and I will tell you which ones are which.

Collimation on these scopes is easy once you get used to the concepts and the precision needed. I adjusted a mates scope about 3 weeks ago now and it took me about 5 minutes to get it done. It was just a fine tune of a previous attempt with the original focusor. That one took me a bit longer because I forgot which ring I was meant to be moving. Simple error but 40 minutes later it finally dawned on me what I was doing wrong.

Just move things slowly so you can work out what is going on and watch what ring moves where. If you get stuck PM me and I will give you my number so we can talk on the phone.