Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
This image was taken October 22, 2009 from my backyard in Austin, TX. It is made up of 75, 4 minute exposures for a total of 5 hours integration time. And yet, somehow, it looks like it still needs more time. I used ISO800 with dark, bias, and flat calibration frames. Equipment includes a modified Canon 40D, Stellarvue SV102ED telescope, Orion Atlas mount running on EQMOD, Starshoot Autoguider running with PhD software, and irrigation system running on a Rainbird controller. But that's another story. Processed with Deep Sky Stacker and PS.
You may notice horizontal banding in the larger size images. I'm still trying to figure out what causes it, and if it's possible to process it out. Any suggestions are appreciated.
Bigger Image Here
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
Edited by Jeff in Austin (10/28/09 09:56 PM)
|
Hermit
member
Reged: 10/26/08
Posts: 48
Loc: Northern California
|
|
What was the temperature? With a little bit of flex between your guide scope and imaging scope, hot pixels can rake across your image and give some streaks, though yours seems more severe than I've seen. Maybe have a look at your raw images and darks to see if this is the case. I think you can take out some of that with noise reduction processing like Noise Ninja, but probably not all.
Best,
Rob
--------------------
Meade LX90 LNT 8" Schmidt-Cassegrain
Standard Wedge, LX90 fork, LX200 tripod
Alan Gee II telecompressor f/5.6
Baader short 1.5cm T-adapter/T-ring
Astronomik CLS-CCD clip filter
Self modified Canon XSi with Baader UV/IR filter.
Meade Model 277 60mm refractor with Orion SSAG
Losmandy V-dovetails for balance and guide scope.
|
Nils_Lars
Post Laureate
Reged: 01/04/08
Posts: 3395
Loc: Santa Cruz Mountains , CA
|
|
Well theres always Noels tools horizontal banding removal but I think there is something else going on here , the 4 min subs and modded camera should have given you enough signal.
Maybe try processing without darks flats bias and see if it goes away.
--------------------
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/
|
jmX
super member
Reged: 04/23/09
Posts: 162
Loc: Orange County, CA
|
|
Use noels tools to remove the banding.
As for the time spent, I'm guessing light pollution is causing your 5 hours exposure to look like 20 minute results. Are you using an Ha filter? Seems like that'd be the way to go for imaging from the city.
--------------------
Jon
C6N + CG5
Skywatcher Equinox 80 + CGEM
http://jmx.ls1howto.com
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Noel's tools were used on the original, it helped somewhat but not completely. I tried a re-stack without calibration frames and the banding is still there, so then I tried a single frame and it looks like there are hints of banding. I used Kappa Sigma clipping on the original so I'll try another method next. I'm thinking the stacking process may be bringing out the details in the bands.
Thanks for the suggestions, guys.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
WarrenS
scholastic sledgehammer
Reged: 03/04/08
Posts: 892
Loc: Orange County New York
|
|
Hi Jeff,are you using a CLS filter? I've gotten the exact same problem with this red noise banding in some of my images but not all of them. I'm also using a 40D although mine is unmodded. I posted a question about this a while back but never got a satisfactory solution. So far, I've only gotten the banding while using a CLS filter, usually in warmer weather but to a lesser extent in the winter. I also use DSS to stack, and use flats, darks,and bias frames. Hopefully someone can help us both out because I don't want to stop using the CLS if in fact that's the problem.
--------------------
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
|
Tonk
Post Laureate
Reged: 08/19/04
Posts: 4349
Loc: Leeds, UK, 54N
|
|
Yikes - I've shot this under virtually the same conditions at a very similar total integration time with a modded 450D and the results are perfect - not a hint of banding. And all stacking was with DSS and Sigma-Kappa.
This sort of points to a poor sensor in your camera, certainly something is up and its possibly to do with the RAW images either the raw lights and or the calibration images, from your comments. Its the strongest suspect
DSS certainly behaved very well for me so I'm less inclined to say its DSS misprocessing - but if your misset DSS options it can do strange things. Maybe if you can list the DSS settings you used we can check that you are not doing anything truely unusual (like using an inappropriate debayering mode)
--------------------
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
|
Tonk
Post Laureate
Reged: 08/19/04
Posts: 4349
Loc: Leeds, UK, 54N
|
|
Something else to try - stack only a small subset of your images and see what that brings out. In could be that some images in the full stack are misregistered and sigma-kappa can cause these out of alignment images to "ghost" along the misregistration axis. Check the delta X,Y values that DSS has measured for each image
How many stars are you letting DSS use for alignment. I use > 5000 on images like these deep in the milky way. More stars in the image and less you are using for restristartion increase chances of misalignments
--------------------
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
|
templec
member
Reged: 08/01/09
Posts: 51
Loc: Hendersonville, TN USA
|
|
The 40d's are notorious for having banding problems. I have it in my 350d on occasion, when I use ISO 800 and stretch the image REAL hard. My opinion, ISO 1600 will do you better for faint nebula...and I don't see the banding in my 350d at 1600. FWIW...
- Craig
--------------------
Orion 10" f/4.7 Newtonian
Astro Tech AT8IN 8" f/4 Newtonian
Orion 80ED
William Optics ZS66
Atlas EQ-G w/EQMOD
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Quote:
Hi Jeff,are you using a CLS filter? I've gotten the exact same problem with this red noise banding in some of my images but not all of them. I'm also using a 40D although mine is unmodded. I posted a question about this a while back but never got a satisfactory solution. So far, I've only gotten the banding while using a CLS filter, usually in warmer weather but to a lesser extent in the winter. I also use DSS to stack, and use flats, darks,and bias frames. Hopefully someone can help us both out because I don't want to stop using the CLS if in fact that's the problem.
Ahh! Good point, I forgot to mention the filter - IDAS LPS P2.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Tonk, thanks for the suggestions! Here are the settings used:
Link to settings screenshot
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
Tonk
Post Laureate
Reged: 08/19/04
Posts: 4349
Loc: Leeds, UK, 54N
|
|
OK - try it again not using mosaic mode -
turn off both "cosmetic" hotpix options
--------------------
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
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Here's what I've tried over the last 2 days...
Standard mode stacking (not mosaic) without "cosmetic" hot pixel optios - no change
Stacking the flats only and stretching - no horizontal bands
Stack using Median combine - has bands
Stacking the darks ony and stretching - has the horizontal bands. This suggests it's either in the camera or has something to do with the stacking, or a combination of both. I'll be trying Nebulosity for stacking next, although I'm not expecting anything diffrent.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
guyroch
sage
Reged: 01/22/08
Posts: 253
Loc: Ottawa, Canada
|
|
Canon 40D are know for horizontal banding. Try dittering your camera every 10 shots or so during your next session. This may help to reduce the banding.
--------------------
750mm 6" Skywatcher Reflector f/5
Celestron CG-5 GT mount
SSAG autoguider mounted on Orion 80mm short tube
Canon 40D unmodified / TC-80N3 remote timer
Orion SkyGlow for Astrophotography light polution filter.
Orion AccuFocus & Bahtinov mask
Bushnell 8x42 h2o® Waterproof Binoculars
Sky Atlas 2000.0 Field Version (Laminated)
Plenty of patience and a wife that doesn’t quite understand my love for clear skies, but let’s me go out anyway ~ thanks honey bunny 
|
guyroch
sage
Reged: 01/22/08
Posts: 253
Loc: Ottawa, Canada
|
|
Also, if you plan using Nebulosity, you might want to try the Bad Pixel Mapping instead of standard dark substraction. This may (or not) help by not transfering the banding noise you also have in your darks - but I not not sure. Remember that in Nebulosity if you use normal dark substraction you do not supply bias frames. However, with bad pixel mapping you do.
Good luck
--------------------
750mm 6" Skywatcher Reflector f/5
Celestron CG-5 GT mount
SSAG autoguider mounted on Orion 80mm short tube
Canon 40D unmodified / TC-80N3 remote timer
Orion SkyGlow for Astrophotography light polution filter.
Orion AccuFocus & Bahtinov mask
Bushnell 8x42 h2o® Waterproof Binoculars
Sky Atlas 2000.0 Field Version (Laminated)
Plenty of patience and a wife that doesn’t quite understand my love for clear skies, but let’s me go out anyway ~ thanks honey bunny
|
Tonk
Post Laureate
Reged: 08/19/04
Posts: 4349
Loc: Leeds, UK, 54N
|
|
Quote:
Stacking the darks ony and stretching - has the horizontal bands.
In which case here is your suspect! Try
1) Stretching a single dark - do you see any banding?
2) Stack - without using darks for calibration. If the banding goes - then your darks were the cause
3) How and were did you take your darks. Straight after the lights while still on the scope, or elsewhere like garage. Were you close to aor well away from other electrical equipment while taking these darks
--------------------
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
|
WarrenS
scholastic sledgehammer
Reged: 03/04/08
Posts: 892
Loc: Orange County New York
|
|
Hi Jeff, good analysis. No surprise there's no banding when you stacked flats only. I've been doing some more testing and reevaluating my older data. My observations about the red banding so far:
1) Red noise in darks made worse when using my CLS filter in warm weather. Increases with longer subs. Much worse at 1600iso than 800, no surprise there.
2) No banding noticed when not using the CLS filter.
3) Never occured before I began autoguiding. When autoguiding, never occured in "freezing weather". I started autoguiding in February.
4) Several posters reported that the 40D was subject to banding, although I never saw that particulat type of banding.
5) Worse when using darks in stacking.
The banding seems to me to be caused by a combination of excess red noise caused by my LP filter combined with the 40D's tendency to possibly show horizontal banding. I don't think it's a function of any DSS stacking necessarily.
My guess is the banding should disappear when I'm shooting in cold weather this winter, if that's the case I may make a lunchbox/gelpak cooler described in a post here last summer.
--------------------
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
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Quote:
Quote:
Stacking the darks ony and stretching - has the horizontal bands.
In which case here is your suspect! Try
1) Stretching a single dark - do you see any banding?
2) Stack - without using darks for calibration. If the banding goes - then your darks were the cause
3) How and were did you take your darks. Straight after the lights while still on the scope, or elsewhere like garage. Were you close to aor well away from other electrical equipment while taking these darks
Stretching a single dark shows bands. More in the red and blue channels than green. The uncalibrated stack has bands as does a single frame after stretching. The darks were done from 3am to 5am immediatly after the images. Temps were within 2-3 degrees and without any thing else on the same power strip. So I think the darks are acquired and processed ok.
I'm starting to think its either a camera limitaton that can be averaged out by dithering, or maybe a camera problem, because the bands seem to be there before any processing takes place. I'm not ruling out a camera limitation because I may just be over stretching. Today I re-processed M42 from last year using my unmodded 50D and I'm getting similar results after processing the same way.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Warren, I'm starting to think that it's a camera limitation...I didn't have this problem before autoguiding, either, and I'm stretching pretty hard to bring out this faint target.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Guyroch - I will definatly try dithering next time... I think it will help.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
Jeff in Austin
scholastic sledgehammer
Reged: 02/26/07
Posts: 801
Loc: TEXAS
|
|
Quote:
The 40d's are notorious for having banding problems. I have it in my 350d on occasion, when I use ISO 800 and stretch the image REAL hard. My opinion, ISO 1600 will do you better for faint nebula...and I don't see the banding in my 350d at 1600. FWIW...
- Craig
I will try ISO1600 next time...people seem to be getting good results with it.
--------------------
There's nothing like having a supportive family, including Second Grader w/ scope, curious toddler, and lovely wife.
Supporter of Austin CSC, Austin CalSky.
|
WarrenS
scholastic sledgehammer
Reged: 03/04/08
Posts: 892
Loc: Orange County New York
|
|
Quote:
Quote:
The 40d's are notorious for having banding problems. I have it in my 350d on occasion, when I use ISO 800 and stretch the image REAL hard. My opinion, ISO 1600 will do you better for faint nebula...and I don't see the banding in my 350d at 1600. FWIW...
- Craig
I will try ISO1600 next time...people seem to be getting good results with it.
I'd be interested in your results at 1600 ISO Jeff. Shooting at 1600 guaranteed I'd get the banding. 800 ISO would be more hit or miss.
--------------------
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
|
Previous
Index
Next
Threaded
Edit
Reply
Quote
[Re: 