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Zambuto Mirrors

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#26 JimMo

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Posted 20 February 2013 - 05:30 PM

Thanks Jeff. She sure is a beauty. I was just admiring it in another thread. Cheers!

#27 jpcannavo

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Posted 21 February 2013 - 07:53 AM

Jeff
Did you say 16" at F7! And I thought I was slow! Wonder if a 2.1" secondary would have still been adequate? I guess a paracorr will never be straining your budget! Nice work!

#28 Jeff Morgan

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Posted 21 February 2013 - 06:44 PM

Jeff
Did you say 16" at F7! And I thought I was slow! Wonder if a 2.1" secondary would have still been adequate? I guess a paracorr will never be straining your budget! Nice work!


Always trade-offs. I thought a bit about the 2.14", and at first I wanted to make it work. But there were a couple of factors to consider:

1) A 2.6" already gets me below the commonly accepted obstruction threshold of 20%;

2) I wanted to take the hassle-factor out of filter use by doing the slide. Using a larger diagonal to push the focal plane further out (easy to do with that skinny light cone) and allows me mount the slide well outside of the incoming light instead of becoming a huge obstruction; and

3) At 2800 mm focal length, I wanted to fully feed an eyepiece for maximum true field. Even with my 31 Nagler I'll only be getting about 0.8 degrees! Going with the 2.14" diagonal would have been pushing it in terms of illumination (a downside of that skinny light cone).

One of the things on my mind has been the AstroSytems diagonal holder. I may order another spider and holder to swap out for evaluation and it would present the opportunity to try a 2.14 diagonal.






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