cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2163
Loc: Scottsdale, AZ
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I know, I know, my standards have become very high indeed, but after imaging for several hours last night and then several hours of stacking and processing I was left with garbage.
I don't know why my flats didn't seem to take, after what I thought was careful framing it turned out to be not what I wanted and focus turned out to be a bit soft. In short a whole night wasted.
I'm about ready to throw in the towel and get some binoviewers and leave this imaging stuff to people who know what they are doing!
After 2 or 3 hours of effort I got this:
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
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www.aznightsky.com
Scottsdale, AZ
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diabolic
super member
Reged: 10/19/06
Posts: 112
Loc: Austin, TX
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I have had several nights like that. I like to think it's just another step on the learning curve ladder, but it's especially frustrating when you get nothing and didn't learn anything either.
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Will
WO Megrez 110 ED • WO ZenithStar 80 II ED • Celestron 9.25" Carbon Fiber SCT • Orion XT10i • Meade ETX-125AT
Canon 40D • Meade DSI-Pro II • SPC900NC
Celestron CGE
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D_talley
scholastic sledgehammer
Reged: 07/07/05
Posts: 890
Loc: Richmond VA
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What were your subs exposure times? How many did you take? Did you take your flats after the image run to remove the dusk specks? Did you take darks to get rid of the amp glow on the right?
I like the photo myself. Just a little more work. (It never ends)
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Dwight
SBIG ST2000xm
TEC 140 APO #74
Meade LX200 14 OTA
Orion 12.5 DOB
Celestron C8+
Celestron 102AZ
Losmandy G11 Gemini
Argo Navis
Canon 350D self mod
Hyperstar
ST-4 Guider
STV Guider
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2163
Loc: Scottsdale, AZ
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Here are the stats:
Scope: Astro-Physics 160EDF at f7.5
Mount: Orion Atlas EQ-G with EQMOD
Guiding: Orion 80mm f/11.4 Guidescope with Meade DSI and PHD as autoguider. Auto guiding exposures .5 seconds.
Camera: Canon 350 EOS XT modified.
Lights: 30 exposures of 2 minutes
Darks: 5 exposures of 2 minutes after the lights.
Flats: 5 exposures using homemade light box. Used cameras auto exposure.
Bias: 5 exposures 1/4000 second of dark.
Stacked and combined in DeepSkyStacker.
Levels and contrast stretched in Photoshop 6.0 then converted to JPG.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
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www.aznightsky.com
Scottsdale, AZ
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D_talley
scholastic sledgehammer
Reged: 07/07/05
Posts: 890
Loc: Richmond VA
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Take a look at your flats to see if they show the dust specks.
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Dwight
SBIG ST2000xm
TEC 140 APO #74
Meade LX200 14 OTA
Orion 12.5 DOB
Celestron C8+
Celestron 102AZ
Losmandy G11 Gemini
Argo Navis
Canon 350D self mod
Hyperstar
ST-4 Guider
STV Guider
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2163
Loc: Scottsdale, AZ
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Thanks Dwight.
Unless I stretch my flats out I don't see any dust specks. With them stretched out I do see the same specks as on the image. I'm wondering if my exposures were too short / long on my flats. How does one judge the exposure of a flat?
Thanks again!
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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D_talley
scholastic sledgehammer
Reged: 07/07/05
Posts: 890
Loc: Richmond VA
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Also what ISO was your camera set for?
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Dwight
SBIG ST2000xm
TEC 140 APO #74
Meade LX200 14 OTA
Orion 12.5 DOB
Celestron C8+
Celestron 102AZ
Losmandy G11 Gemini
Argo Navis
Canon 350D self mod
Hyperstar
ST-4 Guider
STV Guider
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LLEEGE
Running out of Oxygen
Reged: 03/03/05
Posts: 9079
Loc: Cloud-chester,NY
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Been down that road too. Don't quit! You'll get it. I would skip the bias frames. I don't think your flats were properly applied either. Did you correct the luminance of them before applying them? With a modded camera, you need to. Maybe not in DSS???? But I would check into that. Also, where was the histogram hump for your lights?
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"Okay! You draw the straws. I'm-a taking the parachute."
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2163
Loc: Scottsdale, AZ
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ISO 800 which is what I have used with success in the past.
Also I'm shooting from a fairly light polluted area. 2 minutes is about my maximum exposure with this setup.
Clearly there is something wrong with my flats and also probably something wrong with my processing.
I also took 2 hours worth of 2 minute exposures of M45 last night which turned out awful as well. 
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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D_talley
scholastic sledgehammer
Reged: 07/07/05
Posts: 890
Loc: Richmond VA
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I set my camera to ISO 100 and TV mode, which gives me a speed of 1/5000 of a second exposure. I was having problems with my flats and tried this mode and it worked. Are your flats RAW?
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Dwight
SBIG ST2000xm
TEC 140 APO #74
Meade LX200 14 OTA
Orion 12.5 DOB
Celestron C8+
Celestron 102AZ
Losmandy G11 Gemini
Argo Navis
Canon 350D self mod
Hyperstar
ST-4 Guider
STV Guider
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LLEEGE
Running out of Oxygen
Reged: 03/03/05
Posts: 9079
Loc: Cloud-chester,NY
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Quote:
I set my camera to ISO 100 and TV mode
This seems to be the Tonk standard. It works for me, too.
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"Okay! You draw the straws. I'm-a taking the parachute."
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LLEEGE
Running out of Oxygen
Reged: 03/03/05
Posts: 9079
Loc: Cloud-chester,NY
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How did you focus?
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"Okay! You draw the straws. I'm-a taking the parachute."
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Qkslvr
Pooh-Bah
Reged: 06/23/06
Posts: 1316
Loc: NE Ohio, US
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Make sure your flats aren't clipping, they won't work right if they are, and you have to check each color channel.
I always use bias frames, and I usually reuse them. And DSS does have an option for matching temps. At some point if my subs get good enough, I'll worry more about matching temp.
Quote:
I set my camera to ISO 100 and TV mode, which gives me a speed of 1/5000 of a second exposure. I was having problems with my flats and tried this mode and it worked. Are your flats RAW?
At ISO 100 and 1/5000 of a second that has to be pretty close to as quick an exposure as your camera can do, right? I would think your light source is very close to being to bright.
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Mike
Onyx 80ED/N8/CG-5/40D
Edited by Qkslvr (01/11/08 12:56 PM)
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3463
Loc: Doylestown, PA
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When looking at the histogram a flat should be about half the full well.
How were the flats processed and used? They should be normalized and divided into the bias and dark corrected lights.
Keep at it and it'll come together.
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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D_talley
scholastic sledgehammer
Reged: 07/07/05
Posts: 890
Loc: Richmond VA
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It seems that you would still have more image after an hour worth of time with that 160EDF scope.
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Dwight
SBIG ST2000xm
TEC 140 APO #74
Meade LX200 14 OTA
Orion 12.5 DOB
Celestron C8+
Celestron 102AZ
Losmandy G11 Gemini
Argo Navis
Canon 350D self mod
Hyperstar
ST-4 Guider
STV Guider
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Dave M
Post Laureate
Reged: 08/03/04
Posts: 4928
Loc: N.E Ohio
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Quote:
Thanks Dwight.
Unless I stretch my flats out I don't see any dust specks.
Thanks again!
Chris,
Here`s what a typical RAW flat of mine looks like before
calibrated in Images Plus.
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Dave
Meade 16" F4.5 EQ Starfinder
Meade 10" SCT / Losmandy G11
Tak FSQ106ED
Canon 20D
SBig ST-4
http://www.spacew.com/gallery/image006006.html
Ps 19:1 The Heavens Declare the Glory of GOD.
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Mike D
scholastic sledgehammer
Reged: 08/15/07
Posts: 864
Loc: South GA
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I hope you don't mind me hijacking here, but I'm struggling with this also and hopefully someone has an answer.
I read in Jim Solomon's AP Cookbook at:
www.saratogaskies.com
of the necessity to take lights, darks, flats, AND dark-flats or flat-darks.
Anybody take flat-darks using DSS?
Or do you bother taking flat-darks?
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Vixen SXD
Vixen ED80Sf
Hutech 350D
STI Stiletto
Meade 2080
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Qkslvr
Pooh-Bah
Reged: 06/23/06
Posts: 1316
Loc: NE Ohio, US
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flat darks become important if you have to take long exposures to make your flats.
I make sky flats, and they are short enough I don't worry.
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Mike
Onyx 80ED/N8/CG-5/40D
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MartyT
professor emeritus
Reged: 09/28/07
Posts: 682
Loc: Kansas City
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(I'm just now figuring out this whole "flats" thing myself, so anyone should feel free to correct me if I'm wrong.)
Quote:
Unless I stretch my flats out I don't see any dust specks.
You won't - that's normal. Bring a flat image into Photoshop and do an "auto levels" -- you should be able to clearly see the dust and the vignetting. Don't save the image or anything, just use PS to check that it looks right.
If you didn't already, you should be using Tv for exposing the flats - that will adjust the exposure time automatically. I'd leave the ISO at 800 unless your light source is so bright that it saturates the image (check the back-of-the-camera histogram after taking the flat to see if it's fairly well centered.) -- I'd find a less-bright light source if you can't get a good exposure using the same ISO you're capturing your astro images
For me the first order of business seems to be building a light box of some sort; the "t-shirt over the objective" didn't really work well for me on the couple of occasions that I tried it...
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Celestron CGE / C-11 (CGE-1100)
Megrez 90 FD APO / 0.8x FR/FF vIII
QHY8, 350D, DSI Pro, SPC900NC
KWIQ Guider (QHY5)
ETX-125AT
12" Lightbridge
My Astrophoto Gallery
Astronomical Society of Kansas City
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cvedeler
Carpal Tunnel
Reged: 12/20/05
Posts: 2163
Loc: Scottsdale, AZ
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Thanks everyone for you encouragement and advice.
Luke, I focused with a Stiletto IV. My daughter was bugging me while I was doing it so I don't think I did it as well as I would have liked.
I reprocessed my M45 and it looks better. It seems the flats worked this time.
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Chris Vedeler
Astro-Physics 160EDF
Astro-Physics 900GTO
Q453HR / QHY8 CCD camera
Canon 450XSi
----------------------------
www.aznightsky.com
Scottsdale, AZ
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