Astromart

June 9, 2009 05:49 PM Forum: CCD Imaging and Processing/Deep Sky

Coma Cluster - Abell 1656

Charlie, Jason,
Thanks for the comments.

Charles Hakes said:

I like the crop version. Just need more time... Any idea of the sensitivity ratio between your DSLR and your other "astro" cameras?

Charlie

I don't have any quantitative comparison just yet. I can say that the DSLR (on ISO800) is noticeably less sensative than my Art285 camera (like an ATIK16HR - Sony CCD ICX285). I would guess that I need to expose 2x to 3x longer for similar S/N and even that is going to have diminishing returns given the CMOS sensor in not cooled and is generally noisier and is 12 bit.

June 11, 2009 10:30 PM Forum: CCD Imaging and Processing/Deep Sky

Drift NS - 7479

Posted By Jim Thommes

Charlie,
Its nice to get picture data from an activity you don't expect to yield as such. Nice image.

June 11, 2009 10:33 PM Forum: CCD Imaging and Processing/Deep Sky

Drift EW - 6543

Posted By Jim Thommes

Nice capture Charlie. Like Mike says, the hard part is done if you want to go back and get some shorter subs.

June 13, 2009 09:25 PM Forum: CCD Imaging and Processing/Deep Sky

M6 and NGC 6416

Posted By Jim Thommes

Thanks for the comments folks.

David, I too notice the star strings. I think there is something about our visual wiring that draws our eyes to them.

June 14, 2009 08:38 PM Forum: CCD Imaging and Processing/Deep Sky

NGC 4565 - more mount fiddling

Posted By Jim Thommes

Nice image Charlie. I am glad to see you get productivity out of your fiddling activity. Seems like "frosting on the cake".

I think NGC 4565 is an attractive target. It is particularly fun if you get a good seeing night as there is lots of detail. A visit with the color filters is worthwhile as well.

On the mount, are you concerned that the DEC slop is impacting your tracking in DEC? (so you are not DEC guiding?) I have always wanted to figure out how to do a Dec equivalent to the "East side heavy" approch with RA. Of course that implies a deliberate polar alignment offset which seems counter intuitive. Seems that where I am out now is most of my tweaking is done and I suspect differences I see are related to sky position and slight balance / mount differences in those positions. Further tweaking seems to achieve at best diminishing returns and at worst conflicting results. What is your main tweaking area now - Are you tweaking balance optimums? or gear engagement? or what?

June 14, 2009 08:41 PM Forum: CCD Imaging and Processing/Deep Sky