Re: Celestron C9.25

From: Roger Hamlett (rogerspamignored_at_ttelmah.demon.co.uk)
Date: 07/12/04 

Date: Mon, 12 Jul 2004 10:19:24 GMT

"Reef1969" <reef1969@aol.com> wrote in message
news:20040711174605.29691.00001293@mb-m18.aol.com...
> Mass produced scopes will likely vary sample to sample. I don't think
you can
> make an accurate blanket statement that the 9.25 SCT is the best. I
have owned
> two 9.25's, and both were good samples. I am sure there are bad samples
out
> there. No matter what people tell you the mirrors for the 9.25 are not
figured
> with magical dust. That being said they make an excellent all purpose
scope.
The 'key', is that the C9.25, uses a different design from any other mass
production SCT. It has a longer focal length primary mirror, and then a
more gentle magnification applied by the secondary. This makes it
fractionally more forgiving of surface errors in the primary, gives a
flatter focal field, and makes the focusser a little 'finer', together
with reducing the sensitivity to mirror shift. The 'downside', is that it
requires a slightly larger secondary for the same FOV. However in general,
the 'plusses', do seem to outweigh this 'minus'. The other issue this
creates, is that the scope is larger and heavier than 'normal' for it's
aperture.

Best Wishes

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