Cheshire collumation

[strayring]

Hi Star People

I'm not sure if my cheap line cheshire is off. When I measure the crosshairs they appear to be centered.  But when I look through the peep hole with the 45* cutaway covered they're off to one side. The larger quadrant being to side of the cutaway. 

Could the siting tube out of line?

 

 

[strayring]

Let me put this another way.

OK so I'm seeing the eye hole is centred and the cross hairs are centered, what's not straight is the bored tube....

When I check columation the doughnut is spot on, the crosshairs are right I think..... does the fact that the drilled tube is off make any difference?

[Alan64]

Could you take and post an image of the cross-hairs of the Cheshire, like this...

[Ricochet]

Rotate the Cheshire in the draw tube and see if the crosshairs are centred on the doughnut at all angles. 

[strayring]

On 03/12/2019 at 04:11, Alan64 said:

Could you take and post an image of the cross-hairs of the Cheshire, like this...

Ho Alan sorry about the slow response but here goes:::  one of the crosshairs and what I'm seeing thru the eyehole.

 

[strayring]

On 03/12/2019 at 20:12, Ricochet said:

Rotate the Cheshire in the draw tube and see if the crosshairs are centred on the doughnut at all angles. 

Hi Ric. Good idea... I tried that and found my cross hairs are way off the doughnut but stay on the same spot when the eyepiece is rotated. Does this mean I need to reset the secondary first?

[Alan64]

It appears that a component of the tool has slipped out of alignment.  Are you able to repair the tool?  I probably could if I had it before me.

Orion(of California) Newtonians come with a collimation-cap.  I have the Orion "StarBlast 6" kit, and this is the one that came with it...

Did you get one with yours?  If not, are you the original purchaser of the kit?

[Alan64]

The more I look at your first image, it appears that the reflective disk has come loose, and is now askew.  The cross-hairs, on the other hand, appear to be correct.

Edited December 6, 2019 by Alan64

[strayring]

55 minutes ago, Alan64 said:

It appears that a component of the tool has slipped out of alignment.  Are you able to repair the tool?  I probably could if I had it before me.

Orion(of California) Newtonians come with a collimation-cap.  I have the Orion "StarBlast 6" kit, and this is the one that came with it...

Did you get one with yours?  If not, are you the original purchaser of the kit?

I made one from a 35mm film canister.  My collimation is spot on with it. Everything "appears" centered but with the cheshire the crosshairs are way off centre. 

Edited December 6, 2019 by strayring
After thought

[John]

How does a star test look ?

That is the most important thing

 

[Alan64]

11 hours ago, strayring said:

I made one from a 35mm film canister.  My collimation is spot on with it. Everything "appears" centered but with the cheshire the crosshairs are way off centre. 

You can line the underside with a circle of aluminum-foil, the dull side, and for improved illumination of the collimation scene.

As John had mentioned, a star-test is the final test of how well the telescope was collimated.  A basic star-testing tutorial...

https://www.skyatnightmagazine.com/advice/how-to-star-test-a-telescope/

[Geoff Barnes]

I completely agree with the above, once I got my secondary mirror set perfectly with my Cheshire and locked it into place, I now only use a star test to finalise my collimation each time I set up as I know the secondary is right. It almost always needs a slight tweak of the primary screws each time to get that set perfectly, but it is a one or two minute job at most and away I go with everything looking sharp.  I check the secondary with the Cheshire maybe a couple of times a year but it rarely needs adjusting again.