Equinox 80 Collimation Out?

[Euan]

Hi folks,

I've just been looking at my first pics with my Equinox 80 and QHY8 and I think I have fooked the collimation on the scope, as I've had it apart a few times

The vignetting is off centre and its also way off axis in CCD inspector

I've checked the imaging train and everything is rock solid, it's way better than my newt and even that has been results than this

Has anyone collimated this or an ED80?

Thanks

Euan

[FLO]

Before doing anything to the scope check that your QHY8's sensor is centred correctly, I have heard of one or two that were not.

[Merlin66]

You can use a Cheshire collimating eyepiece and a bright LED light to check the collimation. You'll see the reflections from the rear surface and the inter-lens surfaces - these circular disks of light should be concentric.

[harry page]

Hi

Also check the focuser as my camera was loose in it and when I tighned up the screw it pushed the camera to 1 side!!

Oposite the focuser screw is a small grub screw which you can alter to help centre things.

Might not be this but was my problem

Regards Harry

[Euan]

Before doing anything to the scope check that your QHY8's sensor is centred correctly, I have heard of one or two that were not.

Gave it an eyeball check and it looks fine. Hard to tell if it's sitting flush mind you

You can use a Cheshire collimating eyepiece and a bright LED light to check the collimation. You'll see the reflections from the rear surface and the inter-lens surfaces - these circular disks of light should be concentric.

Haven't had a clear spell to try it, so I fired my collimated laser collimator through it and it's hitting the front cell off centre.

Hi

Also check the focuser as my camera was loose in it and when I tighned up the screw it pushed the camera to 1 side!!

Oposite the focuser screw is a small grub screw which you can alter to help centre things.

Might not be this but was my problem

Regards Harry

I've had the whole scope to bits again. The front cell is built into the housing and it's not adjustable. I've had the focuser to bits as well and there is a few screws holding different parts together but none of them seem to be any kind of adjustment screws

When I spin the focuser I can get it slightly closer (see pic) it's on left to right but still off vertically, more playing with screws required

[Merlin66]

Euan,

For the Cheshire testing of objective lenses you don't need to use outside light etc.

Cover the objective with its dust cap, put the cheshire in position and shine a bright LED light into the side of it. This will reflect down the tube and off the back of the objective lens. Looking through the Cheshire rear hole you'll see these reflections as a series of bright disks and rings... these need to be concentric.

Just re-read your comment about the laser: The laser beam should be hitting the centre of the objective. What you are seeing shows the focuser tube is not aligned with the objective..

Undo the three screws holding the focuser in the tube and move it around until the spot hits the lens centrally; re-tighten the screws and re-check.

This needs to be done before anything else!!!

[Euan]

Euan,

For the Cheshire testing of objective lenses you don't need to use outside light etc.

Cover the objective with its dust cap, put the cheshire in position and shine a bright LED light into the side of it. This will reflect down the tube and off the back of the objective lens. Looking through the Cheshire rear hole you'll see these reflections as a series of bright disks and rings... these need to be concentric.

Just re-read your comment about the laser: The laser beam should be hitting the centre of the objective. What you are seeing shows the focuser tube is not aligned with the objective..

Undo the three screws holding the focuser in the tube and move it around until the spot hits the lens centrally; re-tighten the screws and re-check.

This needs to be done before anything else!!!

The Equinox has a different focuser to the ED80, it's held in by screwing in the entire unit into the main tube and then it's locked off by turning the locking ring around it

The other screws hold a few parts of the focuser in place and are not adjustable in any way, the only thing I can think of it packing out some of the roller parts inside to push it to one side

[Merlin66]

Ohhhhh, unfortunately sounds like a pretty carp design!

Can you find a position when the whole focuser is screwed in/ out of the tube where the laser WILL hit the centre ( or close to it.)???

[Euan]

Ohhhhh, unfortunately sounds like a pretty carp design!

Can you find a position when the whole focuser is screwed in/ out of the tube where the laser WILL hit the centre ( or close to it.)???

It's amazingly bad design if there is no way to collimate this, and on the "pro series" no less

I'm going to knock up a template for the front so I can see when it is exactly centre and see if I can get it straight

Thanks for the help

[Merlin66]

I wish you well. The focuser needs to be in the "correct" position before you can accurately collimate the objective.

Keep us posted....

[Euan]

This gets more interesting....

I've taken a flat frame with the focuser in one position, then rotated the focuser 180 degrees. You would expect that if the scope was out of collimation that the centre of the light would flip to the other side....right??

They are both the same...does that mean the CCD in the QHY8 is off centre?

[Merlin66]

Not necessarily... if the focuser thread is cut off square, at an angle to the optical axis then rotating the focuser it will still be at the same angle relative to the optical axis.

At this stage I think using the collimated laser is a better bet to see what is happening. If you can't get the spot on or close there are other problems ( BTW you should probably see the same as the camera saw; the beam sits off centre, where ever the focuser in pointed! - this would vindicate the CCD results?????)

[Euan]

Not necessarily... if the focuser thread is cut off square, at an angle to the optical axis then rotating the focuser it will still be at the same angle relative to the optical axis.

At this stage I think using the collimated laser is a better bet to see what is happening. If you can't get the spot on or close there are other problems ( BTW you should probably see the same as the camera saw; the beam sits off centre, where ever the focuser in pointed! - this would vindicate the CCD results?????)

I see what you mean

Rotating the focuser makes the laser spot on the lens go round in a circle, so it must be the focuser

[Merlin66]

Yup!

Sounds like the focuser is definately sitting off-centre to the optical axis..........

[Euan]

At last I have solved this riddle...

When looking closely at the focuser tube, I noticed if I pushed it right in, it would only touch on one side, the other side had a 1 or 2mm gap

I ended up having to pack out the runners inside the focuser until it was totally square. It took a bit of experimenting but I finally got there

[Merlin66]

I hope the fix works out OK

Proof of the pudding will be the improvement in your next images!!

[Euan]

Alas, even after packing out the focuser, it was still off enough to warrant doing it properly

Just arrived from the US, a Moonlite focuser with DC Motor Option

I never even had to adjust it, the collimation is now perfect, at last!!!

[Takahashi]

lol... sometimes, ingenuity and a bit o' handiwork just ain't enough. Especially when your mouse-cursor is hovering over a "buy me NOWWWW!!!" button.

[Astro_Baby]

Who said refractors dont need collimation

The Moonlite I'm sure has found a friend and anyway you know you wanted it to pose with

When your at a star party you'll get endless people coming along to twiddle your knobs now