Collimation fustration!!!

[NIGHTBOY]

Ok right so adjusting the primary doesn't only move the dohgnut around but brings the focuser circle into the middle of the crosshairs??

[wookie1965]

The primary brings the crosshairs and the black dot into the middle of the doughnut, once you have lined up the secondary that will be central under your focuser.

[NIGHTBOY]

See this is where I'm gettin confused. Please look at the last picture I posted. In this pic I adjusted the screw an Allen blots to bring the 3 primary clips into view. Then the little black centre dot was was off. I then adjusted the primary to bring the tiny black dot into the centre of the smaller outer circles. Now they don't line up with the crosshairs. Do I need to use the primary to get that tiny black centre dot in the crosshairs and the smaller outer should line up to them?? I know what to achieve its just how to get there!!

[NIGHTBOY]

Ill try to explain later with pictures.

[wookie1965]

when adjusting the primary the crosshairs and black dot should move together, when your secondary is set up the doughnut does not move at all, the adjusting screws on the primary will bring the crosshairs and the black dot into the centre of that.

[NIGHTBOY]

Ok then so all I need to do now is guide that black centre dot on to the centre of the crosshairs by using the primary mirror adjusters?

[wookie1965]

The crosshairs of your cheshire should be central over the middle of the doughnut, your bringing the the cross hairs of your scope and black dot into the centre of the doughnut. Heres another link look at the three pictures, http://www.skyandtelescope.com/howto/diy/3306876.html

[NIGHTBOY]

Ok right. So the only adjustments you make on the secondary mirror is to bring the 3 clips into view. All other adjustments are made from the primary.

[wookie1965]

The secondary needs to show a full circle and be under the focuser dead centre once this is accomplished (the hardest part) the next part is easy the primary will bring in the clips and the crosshairs and dot into the centre on the donut and that will be you collimated read through the last one of the first three i posted and the one i just posted carefully before you start tonight then it will all fall into place and you will think to yourself what was all the fuss about. The third post has a warning in red writing as well once you have lined up your secondary DO NOT TOUCH THIS AGAIN he tells you this.

[NIGHTBOY]

Ok great wookie I get you. That screw in the middle of the secondary mirror, is that for left/right adjustment (as you look through the collimating tube) you twist it for up/down.

[wookie1965]

Yes it moves the secondary in/out of scope and twisting it shows the full circle, the three collimation screw are there just to adjust the tilt of the mirror (very minor adjustment).

[NIGHTBOY]

Ok so this is what was happening.

I'd use that screw to get the focuser bang in the centre. Then I would adjust the Allen bolts to try and get a full round view of the primary when I had a full round view if the primary the focuser had moved out of centre. It was like you could either have one or the other.

Is this the trickey part, getting the focuser to stay in the middle whilst getting a full central view of the primary???

[wookie1965]

No your getting a full round view of your secondary when you twist you secondary you can see the mirror making an oval you want this to be a circle, you use the middle screw to get it under the focuser centrally then leave that alone. The primary will then adjust at the back you will see mirror clips and bring crosshairs and dot into the doughnut and your finished.

[NIGHTBOY]

When I put that picture up and you could only see 2 primary mirror clips, to get 3 clips in view I adjusted the secondary mirror, not the primary.

[wookie1965]

Yes sorry with the 3 adjustment screws take a look at this

http://www.vixenoptics.com/PDF/R130_collimation.pdf

http://www.garyseronik.com/?q=node/169 and this

[wookie1965]

This looks like a good website`s as well

http://perfectastronomy.com/collimate-newtonian-telescope/

http://wildernessastronomy.com/resources/intro-astronomy/telescope-use-simplified/adjusting-telescope/

[NIGHTBOY]

Yes so use the screw in secondary mirror to bring all 3 clips into view.

Use Allen head bolts to bring focuser central with crosshairs.

Adust primary mirror so dot is it centre of crosshairs.

[wookie1965]

First two other way around use screw bring mirror central under focuser.

3 screws show all mirror clips

[NIGHTBOY]

Got ya. Will be on it at half 4.

[wookie1965]

Read through them links first especially that third post before trying it will help you no end.

[Carl Reade]

Hi all, I took a photo of mine with yellow card inside the tube so its easier to see.  As Wookie has said your first goal is to make the secondary mirror into a nice circle (IGNORING WHAT YOU SEE IN IT)

When the mirror is a circle (done by turning it left or right) then you want to use the main screw to adjust it in or out so when you look down the fucus tube the circle is central. The space between the edge of the mirror is equal all around with the circle of the focus tube. Hopefully the yellow card makes it easier to see (you have to ignore the black part of the mirror and count it as part of the yellow card.

You should then end up seeing all three clips. That is all you need to look for at this stage still ignoring crosshairs etc. 

Then you are ready to adjust the primary.

Carl

[NIGHTBOY]

Ok will post pics as I go so be on standby!!

[NIGHTBOY]

Cm ones a bit diff to yours carl, my clips ate right at the edge so I would t be able to have the yellow part on mine.

[NIGHTBOY]

And you haven't mentioned the 3 Allen bolts????

[wookie1965]

If you put yellow paper in or red paper in opposite your focuser like it shows you on the third link i sent you it will show up just like Carl`s.