Click here if you are having trouble logging into the forums Cloudy Nights - Official Forums of the 2009 International Year of Astronomy Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User   You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Astrophotography and Sketching >> DSLR & Digital Camera Astro Imaging & Processing Previous   Index   Next   Threaded   Pages: 1 Bob Brunck member Reged: 06/09/08 Posts: 16 Loc: Corvallis, Oregon NGC7008 stock Canon 40D and 25" f/5 (no Banding)       #2622779 - 09/04/08 02:15 AM Edit   Reply   Quote Quick Reply   Hello All, I was fortunate to have an opporunity to do some imaging in the high desert of Central Oregon near Prineville last new moon. After enjoying a few hours of visual observing I focussed my imaging efforts on NGC7008. After processing the 12 subframes that I acquired I discovered that the best result was obtained by averaging the three best 240 sec subframes. These frames had the best guiding. I am finding now that I can consistently focus the camera accurately with live view I also need to have very precise guiding, with no wind at all, no bumping the ladder, and no walking on the concrete pad. At the focal length of the 25" f/5 scope this is a special challenge. This image was obtained with a stock Canon 40D with a 25" f/5 Obsession and Televue photo Paracorr on a Tom O. aluminum dual axis equatorial platform. With the Paracorr the focal length of this system is 3632 mm. This image is the average of the best 3 x 240 sec subframes taken at ISO 800. The ambient temperature was 51oF to 49oF during the imaging. The autoguiding was done with an 8" f/4 guidescope, a Q-guide camera, and PHD software. Since I have started using the 40D for astro imaging I have sometimes seen horizontal banding in my subframes when they are stretched. I am now starting to realize that when I use the 25" scope, to which I have added extensive baffling to elliminate stray light, I never see the horizontal banding in the 40D frames that I sometimes see with my 12.5" scope. I have not yet added a shroud or the same light baffles to the 12.5" and when any stray light is evident in the images I see banding in the 40D frames. When there is no stray light I do not see the banding. I have never seen banding in my dark frames. Has anyone else ever noticed this ... ? Bob -------------------- Bob Brunck 25" f/5 Obsession on Dual Axis Eq Platform 8" f/4 Guidescope 12.5" f/4.8 self-built Dob with Lightholder optics Canon 10D & 40D unmodded http://www.robertbrunck.com/ Post Extras:       nickatnight professor emeritus Reged: 04/14/08 Posts: 643 Loc: Santa Clarita, CA (LA Suburbs) Re: NGC7008 stock Canon 40D and 25" f/5 (no Banding) [Re: Bob Brunck]       #2622834 - 09/04/08 03:47 AM Edit   Reply   Quote Quick Reply   That's lovely Bob. Are you saying that's only 12 minutes of exposure on that dim p-neb? Wow! I wish I had that 25" scope for planetaty nebulas...and everything else up there for that matter. -------------------- nickatnight Celestron CPC 9.25" GPS Lumicon 2" LumiBrite Diagonal Meade s5000 18mm UWA, Meade 6.7mm UWA, Parks G.S-5 10mm, Celestrom 40mm Plossl Parks 2x Barlow, Meade Tele-Extender Celestron f6.3 Focal Reducer Lumicon UHC Filter and Deep Sky Filter Canon Rebel XTi (prime) Canon Powershot G9 (afocal) Canon EOS T-Ring and Parks T-Adapter Lumicon Univ DigiCam Adapter Post Extras:       Bob Brunck member Reged: 06/09/08 Posts: 16 Loc: Corvallis, Oregon Re: NGC7008 stock Canon 40D and 25" f/5 (no Banding) [Re: nickatnight]       #2626457 - 09/05/08 10:35 PM Edit   Reply   Quote Quick Reply   Hello Nick, Thanks for the feedback, and yes that was with just 12 minutes of exposure. I was surprised too. I was however a little disappointed in the general lack of H-alpha response. I know it's an unmodded camera but my old unmodded 10D did a bit better in H-alpha. The central region of this planetary should have been a bit more red/purple. Bob -------------------- Bob Brunck 25" f/5 Obsession on Dual Axis Eq Platform 8" f/4 Guidescope 12.5" f/4.8 self-built Dob with Lightholder optics Canon 10D & 40D unmodded http://www.robertbrunck.com/ Post Extras:       s58y Post Laureate Reged: 12/12/04 Posts: 4861 Loc: Eastern NY Re: NGC7008 stock Canon 40D and 25" f/5 (no Banding) [Re: Bob Brunck]       #2626541 - 09/05/08 11:31 PM Edit   Reply   Quote Quick Reply   Great image of this seldom-seen object. This image was taken at almost 10x the focal length I normally use. -------------------- Hutech 30D, SBIG ST-402 autoguider SV80S, SV66 guidescope AP900, G-11, Barndoor tracker http://www.pbase.com/s58y Post Extras:       Bob Brunck member Reged: 06/09/08 Posts: 16 Loc: Corvallis, Oregon Re: NGC7008 stock Canon 40D and 25" f/5 (no Banding) [Re: Bob Brunck]       #2629857 - 09/07/08 10:04 PM Edit   Reply   Quote Quick Reply   Hello All, I've gotten some helpful feedback and decided to go back in the processing of this image to "lighten it up a bit". I went back to the original 16 bit master TIFF file and stretched it a bit more and set the black point a bit lower. I think it helped. There many more faint stars visible now ... My thanks to Tom, Bob -------------------- Bob Brunck 25" f/5 Obsession on Dual Axis Eq Platform 8" f/4 Guidescope 12.5" f/4.8 self-built Dob with Lightholder optics Canon 10D & 40D unmodded http://www.robertbrunck.com/ Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 13 registered and 27 anonymous users are browsing this forum. 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