Is this collimation of a RC correct ?

[Catanonia]

I have just taken delivery of a 10inch open truss RC scope along with an OCAL electronic collimator.

Not surprisingly, out of the box the scope needed re-collimating. It was close but not close enough

• Does this look collimated to your eyes ? 
• Good enough for F8 or F5.3 ?

Thanks

[powerlord]

So you've got red on focus tube, blue on secondary edge, and green on ? was green centred on edge of primary until you adjusted to put camera on centre ?

And just checking - are you using the focus on the ocal ? that can really help get the circles precisely over the relevant bit.

I'm re-writing the Ocal Manual just now for Ocal, so interested in anything you found difficult/tricky.

stu

[Tomatobro]

I found that even with collimation aids a star test on a defocused star was required for that final tweak.

I use a Chesire and the TSCOLLI and with the focus tube wound fully in (no extension rings fitted) the bright outer ring is adjusted till its an even thickness all the way round. On Your image it looks to be offset a little to the top right?

[Catanonia]

8 minutes ago, powerlord said:

So you've got red on focus tube, blue on secondary edge, and green on ? was green centred on edge of primary until you adjusted to put camera on centre ?

And just checking - are you using the focus on the ocal ? that can really help get the circles precisely over the relevant bit.

I'm re-writing the Ocal Manual just now for Ocal, so interested in anything you found difficult/tricky.

stu

Not sure what I am doing as 1st time

I basically put the red circle where it is as a reference and to fine center the purple cross hairs.

I then manually expanded and contracted the green circle to check it was centered on all round edges I could see.

To do this I tweaked the secondary as it was not centered, then made fine adjustments to the primary.

The blue line was just on screen for another reference point whilst tweaking

Not touched the focuser centering at this stage.

I used a self centering adapter for the camera

 

Truth will come on 1st light with a star defocus test

 

Edited March 9, 2022 by Catanonia

[powerlord]

manual is terrible.

basic process:

red ring on edge of focus tube. use camera focus to get sharp on edge, and get it right on edge. this is the important bit. get this wrong, rest will be wrong - use offset if you need to.

now, your job is to make sure the secondary is centred and circular. use the green circle for this - don't continue until it's precisely aligned with green circle (adjusted for size).

now, next is to get primary mirror centred in the secondary. only need small adjustments to secondary for this. get it bang in the centre and use the blue circle of this - zoom in if you need to. ignore the fact the camera might not  be in the centre. it's the edge of primary just want concentric with edge of secondary.

final step is cross hairs on, and adjust primary so camera lens is right under cross hairs - which should then be also colocated with the centre donut of the primary.

 

[powerlord]

2 minutes ago, powerlord said:

manual is terrible.

basic process:

red ring on edge of focus tube. use camera focus to get sharp on edge, and get it right on edge. this is the important bit. get this wrong, rest will be wrong - use offset if you need to.

now, your job is to make sure the secondary is centred and circular. use the green circle for this - don't continue until it's precisely aligned with green circle (adjusted for size).

now, next is to get primary mirror centred in the secondary. only need small adjustments to secondary for this. get it bang in the centre and use the blue circle of this - zoom in if you need to. ignore the fact the camera might not  be in the centre. it's the edge of primary just want concentric with edge of secondary.

final step is cross hairs on, and adjust primary so camera lens is right under cross hairs - which should then be also colocated with the centre donut of the primary.

 

Oh , and as an imager I can't be bothered with star tests - too much hassle. collimated is collimated imho. I went through this and got it right on my 300 PDS, and first light showed lovely circular stars edge to edge with my CC - so that's good enough for me.

Looking at your pic, something is out - whatever the green is highlighting.

Edited March 9, 2022 by powerlord

[Catanonia]

Started over with your instructions and image below is at the stage of focuser alignment (it was way off)

Getting to grips with it now.

Next to move on to the secondary and then the primary.

Slowly slowly and learning the ropes with the scope and Ocal (yes the documentation of Ocal is pants)

Thanks @powerlord

 

[Catanonia]

@powerlord I think I have it done.

I have enlarged the thickness of the lines to make it easier to see.

[powerlord]

luvely jubbly - that looks perfect to me!

[Clarkey]

1 hour ago, Catanonia said:

I think I have it done.

I would still suggest a star test as this is the last step. However, carefully I have aligned everything visually when I do a star test it is always slightly off.  The good news is that once set I very rarely need to adjust it. Also, once you put the extension rings back onto the scope and star test you might find there is a small amount of tilt (between the mirror and the focuser). Tests up to now assume everything is aligned - which if you are lucky it will be. If you put the cheshire back on with all of the extension rings in place - after doing the star test and getting it 'perfect' - you might find the secondary slightly off centre for this reason.

[Catanonia]

47 minutes ago, Clarkey said:

I would still suggest a star test as this is the last step. However, carefully I have aligned everything visually when I do a star test it is always slightly off.  The good news is that once set I very rarely need to adjust it. Also, once you put the extension rings back onto the scope and star test you might find there is a small amount of tilt (between the mirror and the focuser). Tests up to now assume everything is aligned - which if you are lucky it will be. If you put the cheshire back on with all of the extension rings in place - after doing the star test and getting it 'perfect' - you might find the secondary slightly off centre for this reason.

Yup true test is a star test with image train in place

[Clarkey]

Sorry. Maybe came out a bit wrong. It wasn't meant to be patronizing.

[powerlord]

Let us know how u get on.

[Catanonia]

12 hours ago, powerlord said:

Let us know how u get on.

Will do once I get my guide rings delivered. Going to use either an old ED80 or old WO66 as a guide camera

 

12 hours ago, Clarkey said:

Sorry. Maybe came out a bit wrong. It wasn't meant to be patronizing.

No problems, didn't come across like that

Edited March 10, 2022 by Catanonia