From: Alan Friedman <alan@greatarrow.com>

Date: January 31, 2010 5:17:50 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Mars at Opposition

Nice work on a very cold night Jim! I was out for an hour and half and spent about the same amount of time getting the feeling back in my fingers when I was done.

Milton, there is little advantage to an obstruction-free design for imaging. This is not the case with visual observing, of course.

best regards,

Alan

On Jan 31, 2010, at 4:33 PM, Milton Aupperle wrote:

Hi Jim;

Very Interesting comparison. Thanks for sharing.

Have you ever explored a chiefspiegler design:

http://home.isoc.net/~ejones/

http://home.isoc.net/~ejones/index_files/CHief%20info.htm

http://www.cloudynights.com/ubbthreads/showflat.php?Cat=0&Number=2652523&page=0&view=collapsed&sb=5&o=all&vc=1

I'm thinking that my next scope will likely be in the 10 to 12"
aperture range, but without any secondary obstruction.

TTYL..

Milton Aupperle

On 31-Jan-10, at 1:49 PM, jimchung2338 wrote:

> Saturday night was a little warmer than the -19ºC of Friday night
> and the seeing was supposed to be better according to CSC. I figured
> it would never get better than this so I took the plunge.
>
> This was going to be a C8 vs 12" dob Mars Opposition imaging shootout.
>
> I have this old C8 from the 1990s with the earlier Starbright
> coatings and not the Starbright XLT. And it's really unusual, it
> came with a white paint job from the factory, apparently Vixen sold
> it when Celestron & Vixen shared product line back then. The Ronchi
> tests have always been very good and I've gotten very sharp
> planetary images from it. I wanted to see how good my stock 12"
> SkyWatcher dob mirror would fare against the C8 standard.
>
> As you can see, the C8 reveals far more albedo detail despite its
> smaller aperture. Now this is going to bug me and I'll have to have
> the SW mirror stripped and refigured!
>
>
>
> http://tech.groups.yahoo.com/group/Astro_IIDC/files/Planetary/MarsOpposition2010.jpg
>
>
> Jim