Focusing a SkyWatcher 1.25" illuminated reticule eyepiece

[HunterGeo]

Hi all,

Ordered a SkyWatcher illuminated reticule eyepiece the other day and have found that I can't get the crosshairs to focus.

I am using an ED80 'scope with a diagonal (into which the eyepiece is placed). I found the black thing at the top of the eyepiece (top being where you put your eye, I mean) that screws off; if I undo it enough to focus the eyepiece, it is then too loose and the eyepiece itself moves (making alignment impossible).

Any ideas on how to focus the crosshairs?

Thanks in advance,
David

[Merlin66]

If it's similar to my Meade and Celestron guide eyepieces then before you put the eyepiece into the scope, just look into it and adjust the top "ring" to reach best focus on the internal cross-wire. Don't touch the ring again...
Then insert the guide eyepiece into the telescope and use the normal focuser (like you would do an normal eyepiece) to bring the target into focus.
At this stage the cross-wires should be clearly visible and focused on the target.
Hope this helps.

[HunterGeo]

Hi Ken; thanks for your advice. Sadly, the eyepiece still moves around when using your method. :/

[Merlin66]

David,
Can you explain, or upload a photo to describe what exactly moving around.

[HunterGeo]

Hi Ken,

The focus ring itself moves from side-to-side when it is loosened enough for the crosshairs to be in focus.

I just spoke with Luke at Andrews (as I needed to order a pillar extension tube for the mount) and asked him about the eyepiece. He had the same issue with eyepieces that he had in stock, so it's a problem with the design of that eyepiece itself.

We decided that I would superglue the focus ring onto the eyepiece once I've got it in focus (which I have just done). Hopefully that fixes it. Will post here once it sets and advise how it went.


Cheers,
Dave

[Astro_Bot]

It's a common problem with that (cheap) design. The top does indeed wobble if screwed up any distance, which affects line-of-sight to the crosshairs and therefore accuracy.

The problem with glue alone is that you don't know that the top part is straight/centred when the glue sets.

The top of the eyepiece unscrews completely, so I used cardboard shims (with a hole in the middle - trial and error to find the right thickness) so that the top part could be screwed down tight (and straight) at the right focal point. I later found some rubber mat that was the right thickness and used that as it was less likely to unscrew compared to cardboard. A large machine washer might also work.

If you try any of these and find they work, you could glue them in place permanently, but I don't see the point as you can simply tighten the top part before use.

HTH

[HunterGeo]

True. By the time you posted, I had already glued it together. Thankfully, though, the glue was unsuitable for the surfaces and it didn't set, so I can remove the glue and will put in a locking washer.

I smell a trip to Bunnings tonight! :D

Thanks for the tip.

[HunterGeo]

Small washer wedged in between the top part and the eyepiece proper worked perfectly. Thanks again. :)