Aligning focuser in a refractor

[Slawomir (Suavi)]

Hi all,

Recently I have installed a new focuser on Orion's ED 80mm triplet (the carbon fibre one) and need to align the new focuser to the optical axis.

Would anyone be willing to give an advise regarding the most effective and accurate way of doing this (hardware and software wise)?

Thank you
Slawomir

[glend (Glen)]

What focuser is it? Moonlights are generally aligned from the factory, but do provide three set screws for tuning on the scope. When I built my refractor I just made a target to fit over the front of the scope objective with a small hole in the exact centre . Stick a laser collimation tool in the focuser and see where the spot falls. Tune with the set screws to adjust the laser to dead centre. Then using a normal cheshire technique tune the objective if needed but since you have not touched the objective it should be good. Do a star test as final check. Done.

PS, you need to be confident that your laser is properly aligned first.

[Slawomir (Suavi)]

Thank you Glen,

It is a Moonlite focuser, and I was hoping there is an alternative (and more precise) way of adjusting focuser alignment than with a laser collimator. Something like producing artificial star pattern and analysing it with software.

I stuck my laser collimator into the focuser and the laser light falls pretty much right in the centre of the lens, yet I am getting a CCD tilt with this telescope (the camera is fine with my other scope). So I am hoping there is a finer way of adjusting the alignment.

[Amaranthus (Barry)]

Were you getting any tilt with the original focuser? (e.g. can you analyse your old subs)

[Slawomir (Suavi)]

Not nearly as much, but the carbon fibre tube is the cause of the problem. I noticed there was increasingly more movement between the focuser and the tube, and it is due to Orion's poor design of the carbon fibre tube.

Apart from chucking the telescope to the bin and keeping the focuser, I have two options:

1. Secure the tube and focuser firmly to a doveplate and align the tube with the focuser.
2. Take the lens out, chuck the carbon fibre tube and make my own tube, and put it all together.

At this moment the scope is fine for visual, but not good for the astrophotography.

[Amaranthus (Barry)]

I am using the ED80T CF too Slawomir, and I do notice a bit of tilt on my larger sensor. Fortunately, QHY22 sold a tilt/tip adapter (9mm optical length) that can be used to fix any detected tilt. But my imaging train is way lighter than yours (970 g in total attached to the focuser - I've stuck with the original Crayford for this reason).

[Slawomir (Suavi)]

Thanks Barry,

I have a TS tilt adapter, may try that first before touching the Moonlite.

I think I may try using CCDInspector as well.