Guest Steve Posted June 2, 2012 Share Posted June 2, 2012 Just picked up a 2nd hand Williams Optics Zenithstar ZS66 Petzval refractor for use as a grab and go, and potentially for imaging. It looks in very nice nick to me, considering it is reasonably advanced in age. It came without any eye-pieces or diagonal, but I had read it would take a 2" SCT thread, so assumed all would be OK. The problem is that I have screwed on my WO 2" diagonal and Baader Hyperion zoom, and the only distance I can focus on is between 6 and 10 feet away. Not so useful for deep sky objects!!! Same thing when I tried with a 1.25" diagonal and eye piece. Am I doing something stupid? I've seen mention of extension tubes - do I need something along these lines? (I'm desperately hoping it is me and not the scope!) Link to comment Share on other sites More sharing options...
Tweedledee Posted June 2, 2012 Share Posted June 2, 2012 www.optcorp.com/pdf/WilliamOptics/ZenithStar66Manual.pdf The above pdf might be useful. It shows extenders in use when fitting diasgonals. Cheers Link to comment Share on other sites More sharing options...
Guest Steve Posted June 3, 2012 Share Posted June 3, 2012 Ah yes - I'd found that previously but not cottoned on to the extension tube bit. I'll test this by holding the diagonal away from the eye-piece and see if it helps.... Link to comment Share on other sites More sharing options...
Guest Steve Posted June 3, 2012 Share Posted June 3, 2012 Yup - holding the diagonal about 1" away from the scope with the focusser fully extended I can focus on the tree tops. So I need a 2" diameter extender tube at least 1" long. Spend, spend spend! But the good news is the scope sits happily on my old photo tripod. About as stable as the Greek economy right now, but it will avoid having to get an additional mount in the short term. Link to comment Share on other sites More sharing options...
Guest Steve Posted June 3, 2012 Share Posted June 3, 2012 Solved. The 1.25" diagonal + eyepiece was too short - it needed an extension even when racked full out. The 2" diagonal was too long - it was going in the right direction when racked right in. When I put my 1.25" eyepiece inside the diagonal I was able to achieve focus. Then light dawned and I realised the diagonal already has a 2" extender in, I guess to provide a bit of clearance when fitted to the SCT. When I took it off and screwed the diagonal directly to the scope and added my Hyperion zoom - Bongo! (That is a typo - but I like it!) This all getting a bit heavy for my little tripod unfortunately, but I don't think I have a chance of getting another so soon after buying the scope. AH well. So, I might have to consider using a bit more of my Baader Solar Film and consider getting up early on Wednesday morning after all.... Link to comment Share on other sites More sharing options...
glider Posted June 4, 2012 Share Posted June 4, 2012 Lots of odd extension tubes and bits here, http://www.scopesnskies.com/AstroBoot Link to comment Share on other sites More sharing options...
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