To increase the Field-of-View of my William Optics Zenithstar 80 ED APO I wanted to mount my Meade Focal Reducer f/3.3 but there was a problem: the Zenithstar has a 2-inch push fit eyepiece holder and the Focal Reducer has SCT thread on both sides; my Scope Teknix Filter Wheel has T2-thread and my SC3 cameras have M42 thread!

The solution: a 2 inch to SCT adapter. But: would it focus? And how about vignetting? And coma? Of course without buying a new expensive telescope :o)

Friends pointed me to several suppliers of '2-inch to SCT thread' adapters, such as Scopestuff
While I was still considering what to do - shipment from the US to the Netherlands is a costly affair - a friend of a friend generously offered to donate a '2-inch to SCT thread' adapter, from his surplus stock. HAPPY !

The result: the focal length of the Zenithstar has been reduced from 545mm to 240mm and the Field-of-View with my ATK16IC camera is now 67.84 x 50.88 arc minutes [measured 'on the stars' with K3CCDTools]

Enough words: the following pictures are clear enough (I hope ...)

2-inch to SCT Adapter.
When inserting the adapter into the 2-inch eyepiece holder of the Zenithstar I noticed that something inside the scope was blocking the insertion:
some kind of baffle.
I could not reach focus, so I had to shorten the adapter, which is now - top to bottom - 51 millimetres high.
The adapter with the Meade Focal Reducer f/3.3 mounted [SCT to SCT].
Now with the clamping ring plus T2-ring
SCT clamping ring with T2 ring and M42 ring.
The complete setup.
The felt on the filterwheel is for this
First light of this setup.
I had to hurry because of arriving clouds, so focusing is not perfect, but it looks very promising!
Oh yes, there is some coma at the edges, but later I learned that proper focusing takes care of that.
And after some processing it looks quite acceptable already.
The result: the focal length of the Zenithstar has been reduced from 545mm to 240mm and the Field-of-View is now 67.84 x 50.88 arc minutes.
A second attempt: in spite of 80-90% clouds I could focus a bit better and am happy with pinpoint stars and no vignetting !
Comet 17P/Holmes.
November 7, 2007 20:07 - 20:16 UT.
Imaging: William Optics Zenithstar 80 ED II APO with Meade 3.3 Focal Reducer at f/3 [focal length 240 mm] ,
ATK16IC camera, Astronomik L filter.
31 unguided exposures of 10 seconds.
The complete setup, but now with an SC3 camera mounted.
[I have documented this as a 'how to' reference for myself].