Re: [ATM] Tri-shiefspiegler

["Bob May" <bobmay@nethere.com>]

I haven't built one but have looked through several at RTMC and all of them
have been spectacular instruments to view through.  They work best at the
higher powers as there is some astigmatism in the edges of a low power EP
that isn't symetrical to the view but that is very small compared to the
basic astigmatism of the EP itself in most cases.
Getting the designing program for weird telescopes from the weird telescope
page will do you in good stead if you wish to investigate the whole field of
that type of telescope.  Don't be afraid of the weird resutls from the spot
diagrams as anything within the Airy Disk will be in the Airy Disk view.
I'd also compare the spot diagrams to that of a "normal Newtonian" telescope
for really how good the scopes are.
I'll also note that the Stevick-Paul design will produce some excellent
views with a shorter focal length.
One little note of the Tri-Schief design is that the EP is on the top of the
scope so when viewing stuff near the zenith, you are more looking in the
side of the scope and that is at a nice mid-level point rather than at the
top of the scope, a trait shared by the Stevick-Paul design.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


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