Q. using 2" accessories on older C8?

[mental4astro (Alexander)]

Hi all,

Having a 'new' older orange tube C8, can I use a 2" diagonal and 2" EPs with it?

Currently it has the 1.25" visual back that winds into the back of the C8.

Is the bore of newer C8's bigger?

I've used my Masuyama 35mm EP with it, and it's left me like a kid in a lolly shop. Now I want more!

Cheers,

Mental.

[Gama]

From memory, the threads havent changed.
So it should screw right on.
Bore size, im not too sure, but i remember seeing many 2" diaganols on the old tubes.



Theo.

[erick (Eric)]

I bought an old C8. It came with a 1.25" visual back which I sold. It also came with a GSO diagonal which screwed on without a problem and I have used that for a few years.

But I bought a GSO 2" visual back and it only screwed on a turn and a half. Then I recently bought a 2" 10:1 GSO focusser for SCT and, same deal.

A machinist has now adjusted these new accessories to make them fit the old C8 thread. If you Google, you will find that this is a known problem for the old Celestron C8s - there is information on Cloudy Nights and elsewhere. Nominally, they are 2" 25tpi threads, but something is different about them.

You'll just have to try. The GSO SCT diagonal that came with it looked to be unaltered and it fitted?

I suggest that you tuck the C8 under your arm and march into Andrews or Bintel and experiment.

[mental4astro (Alexander)]

Cheers lads.

Off to Bintel or Andrews then, hi ho, hi ho, hi ho...

[Barrykgerdes]

Originally Posted by erick

I bought an old C8. It came with a 1.25" visual back which I sold. It also came with a GSO diagonal which screwed on without a problem and I have used that for a few years.

But I bought a GSO 2" visual back and it only screwed on a turn and a half. Then I recently bought a 2" 10:1 GSO focusser for SCT and, same deal.

A machinist has now adjusted these new accessories to make them fit the old C8 thread. If you Google, you will find that this is a known problem for the old Celestron C8s - there is information on Cloudy Nights and elsewhere. Nominally, they are 2" 25tpi threads, but something is different about them.

You'll just have to try. The GSO SCT diagonal that came with it looked to be unaltered and it fitted?

I suggest that you tuck the C8 under your arm and march into Andrews or Bintel and experiment.

I had the same thread problem with a Chinese Mak. I could not get the telescope in the lathe without disassembly so I deepenned the thread in the focuser slightly so it would screw on but not so deep that I could not use it on its correct thread.

Barry