Help with Catseye Infinity XLK Autocollimator (duel pupil)

[SimonfromSussex]

I would be really grateful if someone could help me with the Catseye Infinity XLK Autocollimator (duel pupil).

I'm using it to collimate my f4 ts optics Newtonian.

The problem I have is that I haven't purchased the hotspot centre ring so I'm using the standard donut on the primary and this is then hard to compare to the pictures in the instructions.

I think I have got all four circles lined up however I have a second black dot that is confusing me? Is this simply the reflection of the second pupil hole and so nothing to worry about or should I be trying to line up both the black dots? Apologies if this is a silly question!!!

I have tried to take a picture to show the black dot, hopefully you can see it to the left of the ring, this is taken through the central pupil.

Many thanks to anyone that can help.

[rfdesigner]

That looks correct.

I don't have the autocollimator.. but I did make a catseye lookalike centre spot from a paper hole reinforcer, and cut out the segments to make the 'radiation' symbol... I then used a mirror with a peephole attached to my 1.25"-2" adapter that fits snugly into my crayford focusser.

So.. I'd say making your own catseye centre spot should be very easy and would make life easier for you.

The second dot is the second pupil.

Derek

[Kai]

The first thing I would check is if the "donut" is actually in the centre , it's not unheard of for them to be a few mm out.

[Jason D]

I think I have got all four circles lined up however I have a second black dot that is confusing me? Is this simply the reflection of the second pupil hole and so nothing to worry about or should I be trying to line up both the black dots? Apologies if this is a silly question!!!

Yes, it is the 2nd pupil reflection which you can ignore.

I would like to help you to collimate your scope with the XLK. But first describe the steps you have followed thus far.

Jason

[SimonfromSussex]

Many thanks everyone for the replies.

Good idea on making my own catseye spot Derek, I shall give that a go!

Thank you for the confirmation Jason and very kind offer to help me collimate!

A couple of weeks back Rustysplit helped me and we aligned the secondary to give us a nice round circle (or as nice and round as we can).

We then used a Cheshire to collimate the primary and finally finished off using the fairpoint autocollimator which belonged Rusty (Alan).

I took some deep sky shots with the scope and the collimation looked ok.

Alan has been having some problems (to say the least) with the fairpoint so I decided to get the blackcat instead and had a go with it yesterday.

When I put it in I could see three off center circles very clearly so either the scope has slipped out since Alan and I did it or the blackcat disagreed with the fairpoint. I assume that the fourth circle that should have been there was already stacked? I probably should have de-collimated to find it but sadly didn't.

Using the central pupil I then tweaked the secondary to stack two of the circles, I then switched to the cheshire and adjusted the primary back till this was true (and this stacked the third circle), back to the XLK and another little tweak and one final check with the cheshire and that got me to the picture above (through the XLK).

I'm pretty sure I am now collimated but as I say, that other little black dot was worrying me, glad it can be ignored!

The only other thing I'm not sure about now is if the secondary is square enough? There is a slight oval to one edge (pointing to 4pm when I look down the focus tube) which I have highlighted in orange below:

I think I read on one of your posts that this is ok Jason but again any confirmation would be great!

Thanks again everyone for the help.

[Jason D]

I think I read on one of your posts that this is ok Jason but again any confirmation would be great!

Thanks again everyone for the help.

Yes, that is OK as long as that shift is towards the primary mirror. Attached is a photo from my scope.

If you ever get a chance to take a photo from the offset pupil and the Blackcat, I would like to see these. No rush though.

[SimonfromSussex]

Will do Jason, thank you.

It does point towards the primary but not straight at it?

In your last pic above with the four examples, it looks exactly like the top left pic. That is looking down the focus tube and the primary is to the right.

So it's kinda pointing to 4pm if 12pm is the top of the focus tube and 3pm is pointing towards the primary (if that makes sense)?

If that isnt correct, please can I ask, what do I need to move to change the direction of that offset?

[Jason D]

So it's kinda pointing to 4pm if 12pm is the top of the focus tube and 3pm is pointing towards the primary (if that makes sense)?

If that isnt correct, please can I ask, what do I need to move to change the direction of that offset?

Simon, your mirror offset is OK. Do not sweat over it. The offset towards the primary would be ideal but the offset in the 4pm direction is close enough. Correcting it would require a little twist to the secondary mirror clockwise looking down the OTA but it would be too much effort for little gain. I would leave it as is.

As long as the XLK and Blackcat show good alignment, you will get the sharpest image your optics and seeing allow.

Jason

[SimonfromSussex]

Brilliant, thank you very much for your help Jason!

I just need some clear skies to test it now!!!