[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [ATM] Can one build a Newtonian stiff enough to use a Guide Scope?
Hi Walter, have you considered a self guiding SBIG camera ?
Jean Guy
----- Original Message -----
From: "Walter Belhaven" <wbelhaven@yahoo.com>
To: <atm@atmlist.net>
Sent: Friday, May 04, 2007 8:41 PM
Subject: [ATM] Can one build a Newtonian stiff enough to use a Guide Scope?
> Greetings,
>
> I'm considering building a Newtonian for imaging and have a fundamental
> question before I proceed. Is there a consensus of the folks on this
> list as to whether a 9" f/4.5 Newtonian (give or take an inch or a few
> tenths of an f/ratio) CAN be built rigidly enough to allow 30min
> exposures with a Guide Scope; i.e., with sub-pixel differential flexure
> at fl=1200mm or so? If it can be done, would it require materials that
> are prohibitively expensive (or heavy), making it impractical to carry
> such a beast with a modest GEM? In other words, is one all but forced
> to use an Off-Axis Guider with a Newtonian, or can a Newtonian be built
> stiff enough to use Guide Scopes?
>
> I've done lots of imaging with a very cheap 8" Celestron Newtonian. It
> has a woefully undersized secondary for imaging; primary retaining
> clips that create ugly diffraction artifacts; and it flexes like a
> Romanian Gymnast. Seems to me that there are some simple solutions to
> two of these problems -- a "right-sized" secondary, and perhaps the
> conical mirror sans retaining cilps to name a few -- but my query here
> is really whether I can "solve" the flexure problem(s) (and use a Guide
> Scope) or whether I shouldn't even bother trying (and use an OAG). To
> this end, does anyone have a design for a super-rigid 9" f/4.5 that
> they'd be willing to share, especially in regard to secondary sizing,
> materials, focuser placement, etc., etc.?
>
> Thanks,
> Walter Belhaven
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
>
>
_______________________________________________
ATM mailing list http://www.atmlist.net/