extremez
member
Reged: 03/10/07
Posts: 79
Loc: South Glens Falls, NY
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what determines the exposure length of imaging DSO's? can you judge by the histogram of the frame? i was out last week and shot somewhere up to 80 images of m31 at anywhere from 20-30 secs. i didn't have that great of a polar allignment so i didn't go for longer.
putting 20 frames together with registax and messing around doesn't bring anything out.
are exposure times too short? is it my processing? any idea or thoughts?
here's 1 frame from that night. it's 30 seconds so you will see some trailing due to the bad allignment.
M31
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nofxrx
Pooh-Bah
Reged: 07/12/05
Posts: 1460
Loc: palm bay,florida
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I would think that 80 frames would give you something,not APOD worthy,but something...
Try DeepSkyStacker.Its free and is designed for DSO image processing/stacking.
Registax is made for planetary processing.Could be your problem.
Try stacking them all in DSS and see what you get...
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Kolenka
professor emeritus
Reged: 06/01/08
Posts: 600
Loc: Seattle Area, WA, USA
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Also be aware that M31 is tricky because of the bright core, with the very dim outer regions. If you are starting out, it can be tough as it requires 2-3 different sets of exposures of different lengths to get a really good shot.
Usually the histogram will give you an idea, but with how bright the core is, you could get fooled. So really, you should go by what shows up in the subs, because if it doesn't show up in the sub in some way, it won't show up in the final image.
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cam1936
sage
Reged: 08/01/08
Posts: 242
Loc: Alberta, Canada
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On a lot of DSO objects it's as long as you can go without trailing or without background noise washing out your picture. On M 31 it's as long as you can go without trailing and without burning out the core because it's so bright.
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ChazK
Pooh-Bah
Reged: 11/23/05
Posts: 1453
Loc: Melbourne, Florida
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You need about 2-3 hours for M31. To beat the S/N ratio I shoot for 2 minute subs at the very least. Drift alignment will have to spot on unless you AG
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ChazK
Pooh-Bah
Reged: 11/23/05
Posts: 1453
Loc: Melbourne, Florida
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Sorry as to your M31 image. You have more data there than you think. You need to increase the RGB using curves in photoshop or some processing software. What program are you using?
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Tak TOA 130mm/NJP Temma2
Tak FS 60CB
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extremez
member
Reged: 03/10/07
Posts: 79
Loc: South Glens Falls, NY
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I'm using PS elements 5 with Noels tools. I can't seem to find a turorial on processing though. when you say increase RGB what do you mean?
I did download DSS and stacked 67 images of various exposure lengths. This is what i tweaked out of it.
M31 2nd attempt
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I'm a newbie and loving it!!
C8-SGT XLT w/ CG-5 mount
William Optics ZenithStar 80
Orion ShortTube 80(guide scope)
Canon EOS Rebel XT unmodded
Philips SPC900NC webcam
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scully1234
super member
Reged: 09/04/07
Posts: 146
Loc: Rush, NY
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Hey Extremez your second attempt is excellent for such short exposures !
Use the POLAR ALIGN MOUNT utility in your handset and try again. The polar align utility will give you very good polar alignment. It doesn't take long at all to run through it. Once you have done it you should be able to get two or three minute exposures.
If you can manage about 25 one minute exposures for the core then 25 two minute exposures for the outer arms you will get some very nice results !
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Astrophotographer wannabee !
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Edited by scully1234 (10/04/08 09:41 AM)
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Nils_Lars
scholastic sledgehammer
Reged: 01/04/08
Posts: 988
Loc: Santa Cruz Mountains , CA
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Much better , just add some more longer subs and youll have a great shot there.
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Erik
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Stardaug
sage
Reged: 08/03/08
Posts: 210
Loc: Ontario, Canada
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@extremez - your first image looks exactly like mine. I had the same problem. From what I've learned from the helpful people on here, I just needed more exposure time and more shots to stack. Your second attempt is much better. I'm hoping to achieve some better results soon. I've got the astrophotography bug!
Cheers!
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Shawn / Ontario, Canada
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