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Old 03-09-2008, 01:37 PM
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erick (Eric)
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Join Date: Dec 2006
Location: Gerringong
Posts: 8,548
SCT Newbie (very) - questions

Unexpectedly, I have become the owner of a lovely veteran C8

http://www.iceinspace.com.au/forum/s...ad.php?t=33982

I was primarily after the Argo Navis for my 12" reflector, but have fallen for the C8, though I've only had a few brief looks through it and have yet to complete collimation. It's going to be nice little compact grab-n-go scope for me. (If you call that non collapsing tripod "portable" - one review says it is like wrestling an octopus, to get it folded up and into the car!) I've bought the right size DewNot heater to try and keep the dew off the corrector plate. I've disassembled the base, cleaned and re-greased, fitted a modern socket for the 240V power to the RA motors. I've bought a wedge and put it all together and - looked up at the clouds

BUT, out my window today , so tonight is the night to try again.

OK, first questions:-

1. Collimate with the diagonal in place? Yes?

2. With the basic fork mount, I could fix the diagonal (it's a GSO 2" quartz) in a set location for observation. However, up on the wedge I will have to rotate the diagonal to get it into the right viewing position. Hints? Can I do this effectively without buying anything else? All I have done at the moment is smear a fine layer of grease () on the flat mounting surface of the diagonal and tightened it by hand. I seem to be able to rotate it, but I have to watch that the locking collar remains tight. What is the chance it will just flip around unexpectedly and dump my eyepiece on the ground? Tricks to stop this happening?

3. Testing the diagonal mechanical performance. I reckon I centre a star, then rotate the diagonal on the scope and see how close the star stays to the centre? As well, I reckon I also try to monitor collimation by star testing at different rotation positions? Yes?

4. I picked up a 2" helical focusser:-

http://www.iceinspace.com.au/forum/s...ad.php?t=35183

I intend to find a way to fit it to the diagonal in place of the 2" eyepiece holder currently fitted into it. I will remove the current holder, hold the helical in approximate place with a few different eyepieces and see if I can pull focus. Anything wrong with my theory? And if that works, anything wrong with the practice - eg. will turning a helical focusser on the diagonal just stuff everything up? Eg. mechanically? Yes, I need an adapter to fit the helical to the diagonal and I have someone ready to quote turning up one for me. I gotta do it cheaply. Aluminium and I just flock the inside of the adapter tube?

That's more than enough questions to get started!

ps. thanks to all the great folks on IIS who have sold me this equipment for very fair prices.
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