From: "milton_aupperle" <milton@outcastsoft.com>

Date: January 10, 2010 4:17:10 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Mars from Toronto (now Mars from Jan10)

Hi Jim;

Nice Mars Shots. Weather in Calgary has been too cloudy / unstable to shoot anything.

Your smaller mars works out to be 0.2 arc seconds per pixel (70 pixel disk, 14 arc second Mars) and the second big mars is 0.083 arc seconds per pixel (169 pixel disk). Your definitely getting some good resolution there.

I'm not sure which Flea camera you are using (Flea 640x480 1/3" CCD is 7.4 microns / Flea 1024x768 1/3" is 4.65 microns), but the math works out to be 7.6 meter Focal Length (for 7.4 microns) or 5.5 meter Focal Length (for 4.65 microns) for the "small" Mars.

For the Large Mars shot with double barlows, that's 18.4 meter Focal Length (for 7.4 microns) or 13.3 meter Focal Length (for 4.65 microns) which is F58 or F42.

As to Astro IIDC picking the sharpest frames, what was the Gross Alignment Method set to, either "Lunar/Solar" or "Planetary"? That does make a difference with sharpness estimation method used, as Lunar/Solar looks for sharp high contrast edges, where as planetary looks for softer edges. It can make a difference in the result you get.

HTH..

Milton Aupperle

--- In Astro_IIDC@yahoogroups.com, "jimchung2338" <jim_chung@...> wrote:

Hi Willie, thanks!

I was out again this morning at about 1:30 and seeing was good and no wind turbulence so I was able to stack 130/1300 frames per channel at f15.  I took the plunge and double stacked my barlows to get at least f30 (maybe even f50 looking at the image size) and the limits of seeing became very apparent.  I found that I had to hand select my sharpest frames because AstroIIDC seemed to be confused by the presence of dust motes perhaps giving false sharpness values.  

http://tech.groups.yahoo.com/group/Astro_IIDC/files/Planetary/MarsJan10c.jpg

I had wanted to compare how my C8 on a GEM would compare but it was getting a little too cold.  The 12" mirror was definitely instrumental in shooting Mars at 15 fps at 8 metres focal length!

Jim