Grimzella
member
Reged: 02/10/08
Posts: 13
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well here we go. The night started out fine. i took some dark frames with my first attempt at a bright star (Altair i think) it was 11:00 pm The exposure time was 5.7 sec. with 50 images. using Autostar Envisage.
Then i started having problems after midnight. My dark frames were not so dark (see below)
My images (the first one looked great) then they started looking bad.
and this one.. has anyone seen this issue.. is it the camera.. or the software? or is it the scope. i did not have dew or fog on the mirror or corrector plate. what could be causing this?
thank you for any help.
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Djennings
sage
Reged: 07/03/08
Posts: 217
Loc: Katy, Texas
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Hello Grim,
I am no expert by any means but it just may be the camera was getting to warm/hot. I know this camera comes with temp sensors but by touching the camera, did it feel as if it was getting hot or too warm? Were you using any filters at all or just the camera? I may not even be able to give any answers to your responses but I am sure someone on the board will be able to point you in the right direction. Also, did you make any changes to the software when all this started taking place?
DJ
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Orion EON 80mm ED
Orion ST80 Guide Scope/Starshooter
Orion 203mm F/4.9 Reflector Image scope
Orion SkyQuest 8" Dobsonian
Orion StarBlaster 4.5 on EQ Mount
Atlas EQ-G W/GOTO
Canon Rebel XT 350D
Orion Startshoot DSI II
Phillips SPC900NC Webcam
Sony DSC-F717 Digital Camera
1 Loving Wife
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DaemonGPF
Pooh-Bah
Reged: 03/22/08
Posts: 1428
Loc: New Mexico
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How do you take your darks? Do you cover the camera nose or do you cover your scope? Was there any possibility of light leaking in?
Usually when my DSI Pro IIc gets really hot, I start seeing orange, blue, purple pixels littering the screen.
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-Josh
*Orion Starblast Imaging 150mm OTA
*Orion Starblast Imaging 114mm OTA
*Meade 50mm AR short tube OTA
*Meade DSI Pro IIc
*Orion Starshoot DSCI
*CG5 mount
http://cleardarksky.com/c/AlbuqNMkey.html
My Messier Project Gallery
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Grimzella
member
Reged: 02/10/08
Posts: 13
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hello and thank you for the response.
Yes, i did have a light pollution filter on the cameras nosepiece. i did not touch the camera to see if it was warm or hot... but the temp reading in Envisage was 17degrees *C. As far as messing with the software... i may have played with the Histogram sliders or clicked auto contrast. When i made the dark frames.. i did bump up the Avg Exp to 10.. and i did not delete existing darks. 
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Grimzella
member
Reged: 02/10/08
Posts: 13
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-Josh I covered scope Lxd75 10in SN with the cover on the corrector plate end. i am not sure where light would have leaked in. it looks to be clear tonight so i may have another attempt at it.
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MartyT
professor emeritus
Reged: 09/28/07
Posts: 516
Loc: Kansas City
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You're sure it's not dew?
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Celestron CGE / C-11 (CGE-1100)
Megrez 90 FD APO / 0.8x FR/FF III
QHY8
Modified Canon 350D (Baader UV/IR Filter)
DSI Pro (guider), SPC900NC
ETX-125AT
Meade 12" Lightbridge
Astronomical Society of Kansas City
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mnaf
professor emeritus
Reged: 01/03/06
Posts: 626
Loc: Bay Area, CA
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Dew would be my first guess, too.
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~Mike
Atlas EQ-G
Orion 8", AT66ED
Discovery 80mm refractor
Meade LPI, DSI Pro, DSI Pro II
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Grimzella
member
Reged: 02/10/08
Posts: 13
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im almost positive its not dew. i looked thru the scope with a flashlight and the corrector plate and mirrors had no dew,,, they looked clear,, no fog or moisture. guess after i attempt again tonight i will be looking extra close at things like these. i even had the hair dryer out last night,, because i thought dew might be the problem too... but no change.
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Jared
Carpal Tunnel
Reged: 10/11/05
Posts: 1850
Loc: Piedmont, California, U.S.
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Quote:
im almost positive its not dew. i looked thru the scope with a flashlight and the corrector plate and mirrors had no dew,,, they looked clear,, no fog or moisture. guess after i attempt again tonight i will be looking extra close at things like these. i even had the hair dryer out last night,, because i thought dew might be the problem too... but no change.
Perhaps the dew is on the filter rather than on the corrector plate... It certainly looks like dew--everything fits. Sudden severe loss of contrast. Contrast uneven across the frame (see how our fourth image has a "clear" window near the bottom of the frame that is still clean)... There was almost certainly dew somewhere in your imaging train.
I have gotten images just like that when ice started building up on the window in front of my CCD chip. Your camera isn't cooled, so it can't be ice, but dew would look about the same.
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- Jared Willson
- Fluorostar FLT-110 w/ TEC optics
- Vixen VC200L
- Astro-Physics Mach1 GTO
- Stellarvue SV80S
- Takahashi Teegul SP Mount
- STL-11000
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Grimzella
member
Reged: 02/10/08
Posts: 13
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i guess it is possible that it is dew... since i didn't see it.. maybe it was on the LP filter. now that i know what dew may look like, i can look for it harder. My dew sheild is not heated (yet) - This was my very first time with imaging.. so i got happy when i got that first shot. but as the night went on (scope was outside for about 4-5 hrs) After about 3 1/2 hours pictures started degrading. but being inexperienced in astrophotography i guess i didn't look to see where dew can be, and what effect it has on photos. thanks to you guys, i can look at these issues with new hope. thanks again everyone.
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scully1234
super member
Reged: 09/04/07
Posts: 139
Loc: Rush, NY
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Hey Grim,
That first shot is pretty cool !
Colorize it and its a winner !
Your images look like dew is slowly forming on the IR filter in the nosepiece of the DSI II. If this happens again, pop the camera out of the diagonal or whatever extension adapter you're using to connect with the visual back and check it. If you see a milky fog on it give it a quick shot with the hair dryer.
I get this all the time on my DSI guide cam.
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Astrophotographer wannabee !
Celestron C8 XLT on the CG-5 mount
Meade 70mm AZ guide scope
Nikon D50
DSI color
Canon A530 point-n-shoot
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snowdragonusa
professor emeritus
Reged: 09/04/07
Posts: 637
Loc: Denver, CO
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Hey Grim,
The first shot looks great! The second looks like light leaking in during the dark frame take. When the lens cover is on there should be no light at all. If it were dew being seen on that dark frame then it would still lead to a light leaking issue. Even if you had a huge finger print or dust mote on the CCD, a dark frame would not pick that up... unless there is light leaking in. The last shot looks like the "dark" applied to the first image which makes sense. The second image does look like dew though it could very well be light leaking as well.
So, try this little experiment.
1. Connect your DSI to your desktop. Don't worry about the scope right now. If you have the filter slider make sure that is set in AND place filters in the slider. I have read about light leaks WITH filters in let alone without. Also be sure to leave the lens cap on the DSI to simulate a Take Darks environment.
2. In a well lit room with everything hooked up like you were going to take the best M31 image ever seen (sans scope) hold the DSI up to a light source and look at the Envisage preview screen. Is there any thing but darkness or some hot pixels? If so, you have a light leak. If not, then you need to move to the scope and see if there is light leaking there.
3. Set the scope up just like outside. Note: Attempting a polar alignment while inside the house could prove futile... entertaining, but futile.  Connect the DSI to the scope just like you normally would.
4. Get into a "Take Darks" mode by covering the scope just like you would in the field. Now take a bright light source and move it all around the scope. Take your time and move slowly. There may be a leak coming from around the focuser, or perhaps the draw tube...
See if this does anything for you.
Another though about the possibility of dew... Dew forms on the top surface of an object when the surface temp has dropped below the dew point. The only way that you would have gotten dew on the CCD is to leave it exposed pointing up to the sky (i.e. no filters of covers). Alternatively, getting excited about your first really cool star picture and breathing heavy onto the CD would have caused condensation for sure!
In Colorado and other colder environments we have to worry more about frost than dew. But unless you are in a cold area (right now) then that isn't an issue.
Lastly (and this is my personal favorite) this could be interpreted as an amazing shot of noctilucent clouds, or a launch rocket trail, or the foam on a freshly poured coffee!
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Adam
12" LX200R
AT80mm piggyback
DSI Pro, DSI-C, LPI
Denver Astronomical Society
Brighton Astronomical Group
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