From: "Richard F.L.R. Snashall" 
To: Peter 
CC:  atm{at}shore.net
Reply-To: "Richard F.L.R. Snashall" 




Peter wrote:
> Hi,
>
> I'm considering building a folded 16" Newt with a secondary mirror
> mounted at 22.5 Degrees giving a fold of 135 degrees Vs the standard 90
> degrees. Assuming I can baffle the sky light away from the eyepiece are
> there any negative image problems which may occur such a added optical
> aberrations or excessive coma?
>

If flat, there are no aberrations added by the Newtonian secondary. But it
also won't be the traditional full ellipse of the 90 degree folding type
(OTS).  The long axis will be closer in size to the short axis.

                Rick S.

> I'd like to follow Ed Taychert's lead on this idea but I'd like to know
> if there are any negative aspects by departing from the traditional 90
> degree fold. Ed has a really nice page outlining his concept at:
> http://www.irony.com/Ed/astro/18inch/
> I've sent an email to Ed to ask his opinion but he must be out today and
> I unfortunately I need a quick response.
>
> Thanks much for your input.
>
>
> Peter

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