Re: [APML] Newton-cassegrains: opinions sought

["Rick Krejci" <apml@ricksastro.com>]

I just acquired a CN212 and use it for digital photography.  Here is a Canon
10D image using newtonian mode

http://www.ricksastro.com/Gallery/htm/10D_M42.htm

It is slightly cropped and still shows some elongation in the Corners.  I'm
using the standard (if you can call anything standard in Tak land) Wide T
ring, so I'm assuming the spacing from the corrector should be OK.  I may
need to experiment some.

Here is a SXV-H9 CCD image in cassegrain focus with their f9.9 reducer:
http://www.ricksastro.com/Gallery/htm/SXV_m1_cn212cat.htm

Thus far, after about a month of ownership, I like it quite a bit, but I
might be concerned if I were using it for a full 35mm frame in newt mode.
The optics are fantastic, and the focus shift is minimal.  Collimation is
very solid when changing optics and it takes about a minute.  I've had an
8", 10" and 11" SCT, and I would choose the CN212 over any of them, mostly
for it's flexibility and pinpoint optics.

Rick Krejci
http://www.ricksastro.com/


----- Original Message ----- 
From: "Emmanuele Sordini" <vega@bloomingstars.com>
To: <astro-photo@seds.org>
Sent: Thursday, January 08, 2004 4:23 PM
Subject: [APML] Newton-cassegrains: opinions sought


> Hi all,
> searching for a more advanced light bucket than a vanilla SCT, I thought
> about going for a top-quality Newton-Cassegrain (~f/4 - f/15), such as the
> Tak CN-212 or others. That would make two instruments for the cost of a
> single one. My fields of activity are:
>
> 1) deep-sky film photography (otherwise, I wouldn't be posting on APML
> :-)), and
> 2) high-resolution planetary imaging with webcams.
>
> Anybody have experience with such instruments, especially as compared to
> equally-sized SCTs? I feel that they might be better overall, but with
some
> drawbacks (less compact, more sensitive to local turbulence, and a hassle
> to collimate, especially when switching configuration). Furthermore, they
> don't seem to be very popular among amateur astronomers.
>
> Any opinion/advice will be highly valued.
>
> Thanks in advance and clear skies,
> Emmanuele Sordini
>
> _______________________________________________
> Astro-Photo mailing list
> Astro-Photo@seds.org
> http://seds.org/mailman/listinfo/astro-photo
>
>


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