Williams Optics ZS 66 mm not focussing.

[Guest]

A fried has the above refractor. It has a two inch collar where the two inch diagonal if attached. He has told me that he is not able to bring to focus. Any suggestions on a remedy please. Does it need focus tube extensions? 

Edited April 17, 2020 by Guest

[johninderby]

It needs a 2” SCT diagonal. Apparantly won’ focus with a regular push fit diagonal.

https://williamoptics.com/download/support/zenithstar66sd_A4.pdf

[ollypenrice]

John's right.

Olly

[AdeKing]

4 hours ago, johninderby said:

It needs a 2” SCT diagonal. Apparantly won’ focus with a regular push fit diagonal.

https://williamoptics.com/download/support/zenithstar66sd_A4.pdf

Martin,

John and Olly are right, if he is using the original focuser.

The 1.25" visual back threads off and reveals a standard SCT thread to which you can add an SCT diagonal.

The outside diameter of the original drawtube is almost the same outside diameter as a standard 2" nosepiece.

The photo above shows a standard 2" nosepiece sat on top of the drawtube, it won't fit inside, the drawtube is far to small.

Out of interest how has your friend attached a standard 2" push fit diagonal as you can see from the photos, there is no way to do that with the standard Focuser, it's 1.25" or SCT fit only.

Actually, I think WO did originally produce an accessory that made it suitable for a 2" push fit diagonal, does he have that? Or has he fitted a different focuser?

I'm pretty sure I had no probs reaching focus with a w/o 2" SCT diagonal in standard config.

I could never get rid of the focuser slop in mine so in the end I fitted a Moonlite.

Regards,

Ade

Edited April 17, 2020 by AdeKing
Clarified a point.

[johninderby]

The is a WO 2” SCT extender that may have come with the scope so easy to think you can fit that and use a push fit diagonal..

[Guest]

I think that an adapter was fitted to the focusser draw tube and the the normal two inch nose diagonal. 

[AdeKing]

11 minutes ago, Grumpy Martian said:

I think that an adapter was fitted to the focusser draw tube and the the normal two inch nose diagonal. 

Is he running out of inward focus travel or outward focus travel? 

With a 2" diagonal I assume he's running out of inward travel movement.

Is it all 2" eyepieces that won't focus or just a particular one?

I know that in some of my OTAs I have certain eyepieces that will only reach focus with a 1.25" diagonal. However most of my EPs are either 1.25" or dual fit 1.25"/2" fit.

Ade

[AdeKing]

42 minutes ago, Grumpy Martian said:

I think that an adapter was fitted to the focusser draw tube and the the normal two inch nose diagonal. 

According to this thread on CN, there is an in-focus issue with this scope when using the SCT to 2" adaptor and certain push-fit 2" diagonals.

https://www.cloudynights.com/topic/82593-problems-with-my-wo-66-sd-scope/

If the 2" nosepiece of the diagonal he has unscrews it might be easier for your friend to just get an SCT fitting for the diagonal which would gain valuable in-focus distance and may well let it gain focus.

https://www.firstlightoptics.com/adapters/william-optics-sct-adapter-for-2-diagonals.html

I think blue and red versions of this adaptor are also available.

Edited April 17, 2020 by AdeKing

[Guest]

Thanks. My friend is going to order the SCT adapter for his WO diagonal. Let you know how he gets on. 

[Guest]

Focussing issues now rectified thankyou.An SCT adapter was bought as advised. The telescope now focuses correctly.

[AdeKing]

Glad to know that it worked Martin.

Ade