· Get a Cloudy Nights T-Shirt · Submit a Review / Article    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] Forum Archives · Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Astrophotography and Sketching >> Beginning and Intermediate Imaging Previous   Index   Next   Threaded   Pages: 1 Orion_PKFD sage Reged: 01/22/08 Posts: 426 Loc: Vieira do Minho, Portugal Perseus Double Cluster       #3393367 - 10/16/09 04:57 PM Edit   Reply   Quote Quick Reply   Hi folks, This is a "quicky" taken on September 27: SkyView Pro 8" f/5 12x30s 20 Darks Bigger version and description at: http://astro-andregoncalves.blogspot.com/2009/10/perseus-double-cluster.html Comments and suggestions are welcome! Regards, André Gonçalves -------------------- André Gonçalves http://astro-andregoncalves.blogspot.com/ SkyView Pro 8" EQ Dob 4,5" (ATM) 60mm achromatic refractor 10x50 WA 10x25 SPC900NC DSI Canon 1000D Post Extras:       s58y Postmaster Reged: 12/12/04 Posts: 5494 Loc: Eastern NY Re: Perseus Double Cluster [Re: Orion_PKFD]       #3393660 - 10/16/09 08:53 PM Edit   Reply   Quote Quick Reply   Nice, with good star colors -------------------- Hutech 30D, SBIG ST-402 autoguider SV80S, TV102iis Old camera lenses: 800mm f/5.6, 180mm f/3.4 AP900, Barndoor tracker http://www.pbase.com/s58y Post Extras:       drksky super member Reged: 09/01/09 Posts: 113 Re: Perseus Double Cluster [Re: s58y]       #3393723 - 10/16/09 09:43 PM Edit   Reply   Quote Quick Reply   Allow me to ask something not so obvious to me. Why so many darks when you only have 12 subs? Just curious -------------------- Tony C AT8RC C6-R CG-5 ASGT ST80 w/StarShoot Autoguider Canon EOS 450D (Stock) The Drinking Bird Post Extras:       Doubleglaze sage Reged: 11/01/07 Posts: 201 Loc: Pacific NW Re: Perseus Double Cluster [Re: drksky]       #3393764 - 10/16/09 10:09 PM Edit   Reply   Quote Quick Reply   Nicely done with good colors and definition. I use this target as a motivation for improvements in my imaging and processing techniques and still haven't gotten it quite right. Yours is close! Lots of darks is good and not really correlated to how many light frames were taken. I use 30X to 50X for all my darks. The down side is the data collection time, which I generally take care of the next day after imaging if I can match temp correctly. I need a cooled CCD, among all sorts of other things Dark frames are used to determine what the non-light (i.e. dark) signal is from the camera. Once the many dark frames are combined together you can generate a "master dark" which is used to subtract out the dark signal from the image you acquired. Each dark frame has a signal associated with each pixel, and a noise component which changes the measurement of the dark signal on a frame by frame basis. Using lots of darks reduces the uncertainty of what dark signal to subtract out of each image. -------------------- Vixen VMC260L / Sphinx SXD Pentax 75 SDHF Canon 40D / 50mm f1.4 / 100mm f2.8 macro / 28-135 f/3.5-5.6 / 200mm f2.8L http://www.astrophotogallery.org/showgallery.php/cat/500/ppuser/166 Post Extras:       Orion_PKFD sage Reged: 01/22/08 Posts: 426 Loc: Vieira do Minho, Portugal Re: Perseus Double Cluster [Re: Doubleglaze]       #3394185 - 10/17/09 08:25 AM Edit   Reply   Quote Quick Reply   Thank you all, drksky, I had to throw away some subs, but 20 darks arent too much, as Doublegaze said. I was expecting 25 good lights... It was interesting to process because it's difficult not to saturate the stars Thanks, André Gonçalves -------------------- André Gonçalves http://astro-andregoncalves.blogspot.com/ SkyView Pro 8" EQ Dob 4,5" (ATM) 60mm achromatic refractor 10x50 WA 10x25 SPC900NC DSI Canon 1000D Post Extras:       drksky super member Reged: 09/01/09 Posts: 113 Re: Perseus Double Cluster [Re: Orion_PKFD]       #3394496 - 10/17/09 12:10 PM Edit   Reply   Quote Quick Reply   I'm new to digital imaging, so I was just curious. The last time I took astrophotos, I was using hypered Tech-Pan and guiding by hand. -------------------- Tony C AT8RC C6-R CG-5 ASGT ST80 w/StarShoot Autoguider Canon EOS 450D (Stock) The Drinking Bird Post Extras:       Javier1978 sage Reged: 02/12/09 Posts: 227 Loc: Buenos Aires, Argentina Re: Perseus Double Cluster [Re: drksky]       #3396280 - 10/18/09 02:15 PM Edit   Reply   Quote Quick Reply   Very nice image André! -------------------- 6" f5 Sky Watcher Reflector Eq3 mount (Dual Axis) Unmodded Canon 300 D Post Extras:       nofxrx Vendor (HyperCams & Mods) Reged: 07/12/05 Posts: 2488 Loc: Palm Bay,Florida Re: Perseus Double Cluster [Re: Javier1978]       #3397231 - 10/18/09 11:09 PM Edit   Reply   Quote Quick Reply   Agreed,very very nice ,Andre!! Well done.Star colors look great too! CS!! -------------------- Brent Oliver WO-66SD*WO-Megrez102ED-Special Edition CGE Pier-Mounted Artemis285*OrionSSII-Mono AstronomikLRGBHOS*AtikMFW HyperCams&MODS My Gallery Post Extras:       Orion_PKFD sage Reged: 01/22/08 Posts: 426 Loc: Vieira do Minho, Portugal Re: Perseus Double Cluster [Re: nofxrx]       #3401610 - 10/21/09 06:37 AM Edit   Reply   Quote Quick Reply   Thank you very much Brent and Javier! -------------------- André Gonçalves http://astro-andregoncalves.blogspot.com/ SkyView Pro 8" EQ Dob 4,5" (ATM) 60mm achromatic refractor 10x50 WA 10x25 SPC900NC DSI Canon 1000D Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 3 registered and 7 anonymous users are browsing this forum. 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