Help! Secondary on heritage 130p out of line

[harpy]

Hi All,

My secondary mirror got knocked out of line on my sky watcher heritage  130p and i'm trying to realign it but not having much joy.

I have a collimation cap and and a chesire long tube.

 

Below i have two pics, on the right is how it looks through the collimation cap and left is how it looks looking through the cheshire.

for the collimation cap it is my understanding for the secondary to be in line that thick outter black line should be an even circle am I right in thinking that?

and for when looking through the chesire long tube the cross hair should be going through the center of the donut?

 

 

So when i then use the chesire with cross hair and center the donut on that as in the below pic, the collimation cap looks lie the second picture below.

 

Which is best to use when intially trying to realing the secondary with the focuser. i was using the collimation cap, but finding it very hard to get the secondary exactly circular.

 

 

 

 

Am i right in thinking it the black thick outer line that needs to be evenlingy circular in order for the focuser and secondary to be in line?

 

i'm using the middle screw to try and get this in line. but can never get it properly in line the top picture above is the best ive been able to get but when i then look through the chesire it looks compeltely out of line with the cross hairs so im getting confused.

Any help greatly appreciated. I've spent last night and half of today trying to get it in line again.

 

[NGC 1502]

Collimation is not far off.....

Before proceeding best to make sure the tube is at full extension with the two legs clicked into place.

You’ve probably done that, however worth a check......

[Neil H]

Hi i dont know about your scope but if the secondary mirror has a central screw and 3 smaller screw position around it you use centre screw so that mirror  is centre in the focal tube of the focuser the mirror should look round not oval if you use card to block off behind it so you cant see main mirror it makes it easy to see secondary mirror once this is centre remove card use a collimation cap if you have one if not use the Cheshire  to adjust the secondary  mirror using the 3 small screws to adjust so you can see the 3 main mirror clips the same amount on each clip thats done now dont touch it any more

Now adust the main mirror using the collimation screws so the dough nut is centre of the Cheshire then your done some fast scopes have a little off set i dont know if yours has but if you get it as close as possible  and do a star test to check collimation 

Look at astrobaby guide on her site it will help

[harpy]

Yeah I think where I’m getting confused is the cross hairs don’t come into it when I’m aligning the focuser and secondary do they? I’m just trying to get the secondary into the middle of focuser and using the middle screw so the secondary looks circular is it?

And then to align the secondary to primary using the 3 outer screws on secondary..

And then finally use the primary screws to aline primary.

I was aligning the focuser and secondary with collimation cap, and then putting in the Cheshire with cross hair and expecting that to be in the center.

[Pixies]

Forget about the collimation cap for now. Use the Cheshire as a sight tube, to align the secondary under the focuser. You can put a piece of paper over the bottom section, to hide the primary while you do this.

 

Once your are happy with this, take off the paper and then adjust the tilt of the secondary to get the cross-hairs over the doughnut. Then the secondary is done.

 

 

[Alan64]

I block the secondary-mirror's view of the primary-mirror, with paper in between the two, whilst aligning the secondary-mirror with the focusser, and I use the cross-hairs of the sight-tube(Cheshire) to centre it...

...nice, even slices of pie.  It helps to zoom in with a camera, and for finer adjustments.  The secondary-mirror rotates and tilts, both.  It's like a gyroscope...

https://www.youtube.com/watch?v=p9zhP9Bnx-k

It can be maddening, and is oft a source of fits.  But once it's understood, calm ensues.

By blocking the primary-mirror, you can see just the secondary-mirror, and to tend to that, first.  After you verify that it's more or less a perfect circle, you then remove the paper and begin to slowly, carefully, aim the centre of the primary to the centre of the secondary.  Patience is key in that.  Once that's done, you should see something like this...

Note that there is a blurred set of cross-hairs within the outer area, and a sharp set in the centre over the centre-spot of the primary-mirror.  You want all three to line up with each other, as shown, and then you're golden.

After that is accomplished, tighten the screws of the secondary, to secure it.  When doing that, I use a collimation-cap whilst tightening, watching the scene to ensure no shifting takes place...

I watch that black dot in the very center, and within that reddish centre-spot of the primary, and as I tighten the screws.  You can tighten the lock-screws of the primary-mirror as well, but that's not as critical as those for the secondary.  You want the screws for the secondary to be tighter than a shirt two sizes too small, but not to the point of breaking or stripping. 

This tutorial may be of help as well.  The telescope used within is similar to your own...

https://garyseronik.com/a-beginners-guide-to-collimation/

[wookie1965]

http://www.schlatter.org/Dad/Astronomy/collimate.htm

Use this shows you all about placing paper opposite the focuser and how to block the image from the primary.

[Alan64]

On 04/10/2020 at 13:36, wookie1965 said:

http://www.schlatter.org/Dad/Astronomy/collimate.htm

Use this shows you all about placing paper opposite the focuser and how to block the image from the primary.

Incidentally, I had that tutorial bookmarked, and for quite some time.  But when I tried to access it recently, it took me to a site selling pills.  Even when I tried to find the site by searching, pills still.  I'm still scratching my head over that.  Thanks for linking to it, as yours is genuine, and I've now bookmarked it.

[Pixies]

On 04/10/2020 at 19:36, wookie1965 said:

http://www.schlatter.org/Dad/Astronomy/collimate.htm

Use this shows you all about placing paper opposite the focuser and how to block the image from the primary.

This guide confuses me. I appears to miss the adjustment of the secondary to centre the image of the primary within it. It goes straight from aligning the secondary under the focuser, to adjusting the primary.

[wookie1965]

I have just read through it again and it tells you every step to measuring the spider to backing off the 3 collimating screws holding the secondary with your hand while backing off the centre screw, making sure you see a perfect circle of the mirror and equal distance all around it.

Nipping up the centre screw not too hard. Take the piece of paper paper blocking the primary now adjust the 3 collimating screws so all the mirror clips are in the view the same amount. That's it secondary is done as long as you don't drop or bang the tube this will stay in place. Now follow the primary mirror instructions and your done. 

The 3 collimation screws you need to back one off tighten another at the end make sure all 3 screws are nipped up and the centre screw and that's it, seems hard now once you have done it it's like riding a bike. 

Edited October 6, 2020 by wookie1965

[cletrac1922]

i'm using the middle screw to try and get this in line. but can never get it properly in line the top picture above is the best ive been able to get but when i then look through the chesire it looks compeltely out of line with the cross hairs so im getting confused.

Any help greatly appreciated. I've spent last night and half of today trying to get it in line again.

The middle screw is the locking screw for the secondary mirror

The three outer screws are for alignment

Just shine a torch with red filter into the focuser, without an eyepiece, then adjust the secondary so that the red beam is in the center of primary, then use your collimator from there final adjustment

John

[AstroMuni]

6 hours ago, cletrac1922 said:

Just shine a torch with red filter into the focuser,

Is there a reason for the red filter?

[cletrac1922]

20 hours ago, AstroMuni said:

Is there a reason for the red filter?

Reduces the amount of white light been reflected back up the tube

Why most observers also wear a red head lamp, or use red torch when observing, or doing AP

White light also impacts on your night vision

John

 

 

[AstroMuni]

I was assuming you would do the adjustment of the secondary in daytime, hence my question about red filter 🙂