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Captured by
Douglas Rollain

Lion Nebula SH2-132 - RC71

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Posts Made By: Jim Thommes

February 13, 2006 05:53 AM Forum: CCD Imaging and Processing/Deep Sky

M78 - Less McNeil

Posted By Jim Thommes
Thanks for the comments guys.

Yeah, amazing that one year its there and the next its not. I had heard rumors that McNeil's Nebula was captured in some archival 1966 image. It would sure be interesting to see that. I guess if a nebula is excited by a variable star it will be variable as well? Anyway, this one seems like an extraordinarily long cycle if thats what it is.

February 18, 2006 11:52 PM Forum: CCD Imaging and Processing/Deep Sky

Sharpless 2-240

Posted By Jim Thommes
Dennis,
Cool image. I hadn't considered this one before, but it looks like an interesting wide field object.

Congrats on the capture and the processing.

February 20, 2006 01:00 AM Forum: CCD Imaging and Processing/Deep Sky

Seagull Nebula - HA-RGB

Posted By Jim Thommes
Thanks for the comments guys.

Eric, Witch Head you think? Well maybe so. Perhaps that's what I should call it considering my sorry attempt at the real Witch Head.


February 22, 2006 05:55 AM Forum: CCD Imaging and Processing/Deep Sky

Seagull Nebula - HA-RGB

Posted By Jim Thommes
Dan, Dean,
Thanks for the comments...

Dan, I did use noise reduction while the background level was a bit high. The motling got kind of noticeable as a result.

February 25, 2006 11:23 PM Forum: CCD Imaging and Processing/Deep Sky

Bode's Galaxy M81

Posted By Jim Thommes
Johannes,
Very nicely done. Congrats!

Looks like the big aperture and long focal length really brought out the detail. Very sharp and impressive.

February 26, 2006 11:23 PM Forum: CCD Imaging and Processing/Deep Sky

NGC 2903

Posted By Jim Thommes
Thanks for the comments guys.

Daniel, Thanks for noticing the improvement. Some of that is more experience, some is better equipment. This is such a fun activity!

March 10, 2006 04:21 AM Forum: CCD Imaging and Processing/Deep Sky

NGC 2903

Posted By Jim Thommes
Nice shot Dan. Nice bold color - especially the red and the stars. I like the lesser clipped image better as well - thanks for the rework.


March 10, 2006 04:26 AM Forum: CCD Imaging and Processing/Deep Sky

M-81 and M-82

Posted By Jim Thommes
Michael,

Looks good to me on the M81 / M82. I liked your M101 too.

March 11, 2006 06:17 AM Forum: CCD Imaging and Processing/Deep Sky

A couple of Messier Open Clusters

Posted By Jim Thommes
Gee guys, thanks for the comments and encouragement.

Sorry Jeff, no more Messier Opens in the oven, the rest are some obscure NGC's.

March 11, 2006 06:05 PM Forum: CCD Imaging and Processing/Deep Sky

6.3 SCT focal reducer on a refractor?

Posted By Jim Thommes
Mark,
I have used a 0.63 SCT reducer on my Megrez II refractor and have several images on my website with this set up. I am pretty satisfied with its flatness, but I do have to process out some secondary spectrum.

Be careful with back focus. I do not use the adapter because I picked up a 0.63 reducer at a swap meet that was machined to a short 2 inch nosepiece - so it fits further in the focuser than it would with the adapter you mention.

Now the Megrez I use is known for it's deep infocus, yet I don't think I can do anything past a 0.5 reduction and still reach focus. I know Steven recommended a CCD back distance of 110 mm, but I believe the FL of the 0.63 reducer is about 230mm and my calculations would put the CCD at about 85 mm back distance.

So I guess the advice here is be prepared to shorten the reducer to CCD distance in order to achieve focus. If you can reach focus on a 0.63 reduction, fine, but you may have to bring in that distance and settle for a 0.66 or 0.72 reductions.

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