focusing DSI II on ST80 trouble

[troypiggo]

Was so excited to try out the new guide scope (Skywatcher 80mm f/5) and camera (Meade DSI II Pro) tonight...

...but couldn't get focus :(

With the camera "prime", ie connected directly into the scope's 1.25" focuser, I couldn't get focus even with it focused all the way out. The scope came with a kit of 2 1.25" eyepieces and a 1.25" 45 diagonal, so thought I'd try that. But with the camera in the diagonal it seems it was too far now, and couldn't get focus with it all the way in. Guess I need somewhere in the middle...

Similar problems when I tried it on my ED80 Pro. Just couldn't get focus all the way out prime, and with 2" 90 diagonal couldn't focus all the way in.

I'm guessing I need some sort of extension tube? How do I know or work out how long to get? It'll need to be a 1.25" one.

Anyone else have this setup with similar problems or am I missing something silly?

[Merlin66]

You'll need a 50mm extension tube to go between the focuser and the DSI.
You can't use the diagonal with the camera.
I have exactly the same set-up ( ST80+DSI IIpro) but changed the focuser to a 2" Crayford type. Gives better stability to the attachments etc etc and means I have interchangeability between all the other telescopes.

[troypiggo]

Thanks Merlin. Will look into that. 50mm still relevant to both 2" and 1.25"? Same either way? Might look into 2" focuser down the track.

[renormalised]

Ya beat me to it!!!!:P:D

[troypiggo]

Can't find them at Bintel, only the 2" ones...

[renormalised]

Try MyAstroShop (http://www.myastroshop.com.au/).

[peter_4059]

Troy,

What about one of these (unscrew the nosepiece off the front of the DSI and put this in its place then re-attach the nosepiece to this:

http://www.myastroshop.com.au/products/details.asp?id=MAS-407C

If that doesn't work and you can't find a 1 1/4" extension tube you can get a cheap barlow and screw the lens off - I got one of these and use it for that purpose:

http://www.myastroshop.com.au/products/details.asp?id=MAS-283

Happy to let you give it a try if you want.

Peter

[troypiggo]

Good idea. Just phoned York Optical (gotta go into the Valley today anyway for work), they don't have any 1.25" ext tubes, but do have 1.25" barlows for $39 so might try that. Thanks for the lateral thinking, Peter. :)

... [update] got it at lunchtime.