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[Login] Forum Archives · 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 | 2 | (show all) Nils_Lars Post Laureate Reged: 01/04/08 Posts: 3395 Loc: Santa Cruz Mountains , CA Re: Diagonal Noise Pattern [Re: Mike Clemens]       #3400451 - 10/20/09 03:38 PM Edit   Reply   Quote Quick Reply   The problem with Dither is if your target barely fits in the FOV , guess you just have to Dither and then do a mosaic? -------------------- Erik Orion Atlas Self Hypertuned (EQMOD) Orion ED 80 Williams Optics VII reducer Celestron 8" SCT Orion Starshoot Autoguider PHD guide Canon 400D Hap Griffin Mod w/Baader filter Astronomik clip-in LP filter and 12nm Ha Stilleto CVF and Bahtinov mask Tamron 75-300mm&28-80mm lenses NexImage webcam http://www.flickr.com/photos/31986095@N05/ Post Extras:       roundel325 member Reged: 10/09/07 Posts: 31 Loc: Healy, AK Re: Diagonal Noise Pattern [Re: Nils_Lars]       #3400501 - 10/20/09 04:03 PM Edit   Reply   Quote Quick Reply   Ah-ha! Possible breakthrough! I restacked it without flat field correction and the the streaks are gone (but now with lots of vignetting of course). Then I did some reading and it seems I should lower the iso to base for the flats (some conflicting reports on this). I have been shooting all my flats at the same iso as the lights. Could noisy flats be the problem? I will reshoot the flats today and see... Post Extras:       Tonk Post Laureate Reged: 08/19/04 Posts: 4349 Loc: Leeds, UK, 54N Re: Diagonal Noise Pattern [Re: roundel325]       #3400511 - 10/20/09 04:09 PM Edit   Reply   Quote Quick Reply   Shoot a lot of flats - I shoot 36 as my standard, and shoot bias as well. You need the flats at same ISO as lights/darks/bias - IF you are adding bias frames into the mix. If you are not using bias - then aim for lowest ISO -------------------- Televue 85, GM-8/Gemini, Canon 40D (unmodded), Canon 450D (modded w/Astronomiks clip-ins - UV/IR, OWB) Coronado SM60/BF10, Baader Herschel Wedge Leeds Sky Clock Ripon Sky Clock Post Extras:       roundel325 member Reged: 10/09/07 Posts: 31 Loc: Healy, AK Re: Diagonal Noise Pattern [Re: Tonk]       #3400540 - 10/20/09 04:22 PM Edit   Reply   Quote Quick Reply   Tonk, Do the bias frames need to be shot at the same temperature at the lights/darks? Post Extras:       KevinUK Vendor (DSLR-AstroMod) Reged: 08/22/07 Posts: 720 Loc: N 51'53 W 00'25 Re: Diagonal Noise Pattern [Re: roundel325]       #3401503 - 10/21/09 03:18 AM Edit   Reply   Quote Quick Reply   The verdict still isn't out on this as far as i'm concerned, I continue to experience horizontal banding in all my images, RAW frames and stacked, irrespective of what I've tried to do. Will be watching this for further developments. Thanks for the additional insight, and at least I'm not alone, but it does seem only some of us are cursed with this annoying and destructive anomaly. -------------------- DSLR AstroMod DSLR filter removal and replacement packages http://www.dslrastromod.co.uk ------------------------------- Post Extras:       WarrenS scholastic sledgehammer Reged: 03/04/08 Posts: 892 Loc: Orange County New York Re: Diagonal Noise Pattern [Re: roundel325]       #3401630 - 10/21/09 07:03 AM Edit   Reply   Quote Quick Reply   As Tonk hasn't replied yet, bias frames shouldn't be temperature sensitive as they're shot at the fastest shutter speeds, 1/8000th of a second for instance. -------------------- Warren Astro-Tech 127EDT Celestron Onyx 80ED Astro-Tech Field Flattener C8 (circa 1983 Orange Tube) Atlas EQ-G, Orion SSAG Canon 135mm F2.8 Canon 40D, Astronomik CLS clip filter Leica, Minolta binos Post Extras:       roundel325 member Reged: 10/09/07 Posts: 31 Loc: Healy, AK Re: Diagonal Noise Pattern [Re: WarrenS]       #3402285 - 10/21/09 02:16 PM Attachment (5 downloads) Edit   Reply   Quote Quick Reply   YAY! Noise in the flats appears to have been the problem. I reshot the flats (x36) at base iso and the noise is much more under control when stretching, and no diagonal patterns. I have not tried adding bias frames to the iso1600 flats yet, which may also fix the problem. Right now I am just ecstatic because I get to go back and restack all my previous images with these low iso flats and see how much better they are! Thanks everyone for the tips! Hopefully future noobs will find this thread when they experience the same problem. The final image (severely degraded to get <100k). Unmodded camera. Post Extras:       Mike Clemens Post Laureate Reged: 11/26/05 Posts: 4255 Loc: Wasilla, Alaska 61N Re: Diagonal Noise Pattern [Re: roundel325]       #3402292 - 10/21/09 02:19 PM Edit   Reply   Quote Quick Reply   looks great! -------------------- historius apochromaticus Post Extras:       Nils_Lars Post Laureate Reged: 01/04/08 Posts: 3395 Loc: Santa Cruz Mountains , CA Re: Diagonal Noise Pattern [Re: Mike Clemens]       #3402545 - 10/21/09 04:12 PM Edit   Reply   Quote Quick Reply   Thats cool man , im glad you got it all figured out. -------------------- Erik Orion Atlas Self Hypertuned (EQMOD) Orion ED 80 Williams Optics VII reducer Celestron 8" SCT Orion Starshoot Autoguider PHD guide Canon 400D Hap Griffin Mod w/Baader filter Astronomik clip-in LP filter and 12nm Ha Stilleto CVF and Bahtinov mask Tamron 75-300mm&28-80mm lenses NexImage webcam http://www.flickr.com/photos/31986095@N05/ Post Extras:       Pages: 1 | 2 | (show all) Previous   Index   Next   Threaded   Extra information 8 registered and 10 anonymous users are browsing this forum. 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