Is this vignetting?
- Larry 1969
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Re: Is this vignetting?
Larry
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
- UlteriorModem
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Re: Is this vignetting?
Here is my pass at just the single frame completely un-calibrated. There is a good deal of vigenetting in the data made worse by the high levels of sky glow. Neither of which you can do much about. A good set of calibration files will help with that though.
L_0090_ISO800_180s__56F by Tom Whit, on Flickr
Current Equipment:
Mount: Celestron CGX-L
Scope: 130mm f7 APO
Cam: ASI071mc-pro
- startoolsastro
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Re: Is this vignetting?
The issue is most likely failure to remove stacking artifacts. In the image you posted I can see a one pixel high stacking artifact at the top and at the bottom, as well as a one pixel wide stacking artifact to the left and to the right.
For some reason,
If stacking artifacts are not removed not removed (cropped), Wipe will, in turn detect the darker-than-real-background artefacts and will then locally back off, as it doesn't want to clip your signal by subtracting the bias/gradients it found from it. Wipe is - by design - very careful.
From the docs;
Preparing data for the Wipe module
^ Leaving stacking artifacts in will cause Wipe to interpret the anomalous data as true background, causing it to back off near the location of the artifacts.
It is of the utmost importance that Wipe is given the best artefact-free, linear data you can muster.
Because Wipe tries to find the true (darkest) background level, any pixel reading that is mistakenly darker than the true background in your image (for example due to dead pixels on the CCD, or a dust speck on the sensor) will cause Wipe to acquire wrong readings for the background. When this happens, Wipe can be seen to "back off" around the area where the anomalous data was detected, resulting in localised patches where gradient (or light pollution) remnants remain. These can often look like halos. Often dark anomalous data can be found at the very centre of such a halo or remnant.
The reason Wipe backs off is that Wipe (as is the case with most modules in StarTools) refuses to clip your data. Instead Wipe allocates the dynamic range that the dark anomaly needs to display its 'features'. Of course, we don't care about the 'features' of an anomaly and would be happy for Wipe to clip the anomaly if it means the rest of the image will look correct.
Fortunately, there are various ways to help Wipe avoid anomalous data;
- A 'Dark anomaly filter' parameter can be set to filter out smaller dark anomalies, such as dead pixels or small clusters of dead pixels, before passing on the image to Wipe for analysis.
- Larger dark anomalies (such as dust specks on the sensor) can be excluded from analysis by, simply by creating a mask that excludes that particular area (for example by "drawing" a "gap" in the mask using the Lassoo tool in the Mask editor).
- Stacking artefacts can be cropped using the Crop module.
- Larry 1969
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Re: Is this vignetting?
I think I understand. My first step is AutoDev then Bin 50%.
I guess crop should be my next step instead of wipe.
I will reprocess this and report back.
Larry
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
- Juno16
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Re: Is this vignetting?
Let us know how that works out. I always use Intersection stacking in
Scopes: Explore Scientific ED102 APO, Sharpstar 61 EDPH II APO, Samyang 135 F2 (still on the Nikon).
Mount: Skywatcher HEQ5 Pro with Rowan Belt Mod
Stuff: ASI EAF Focus Motor (x2), ZWO OAG, ZWO 30 mm Guide Scope, ASI 220mm min, ASI 120mm mini, Stellarview 0.8 FR/FF, Sharpstar 0.8 FR/FF, Mele Overloock 3C.
Camera/Filters/Software: ASI 533 mc pro, ASI 120mm mini, ASI 220mm mini , IDAS LPS D-1, Optolong L-Enhance, ZWO UV/IR Cut, N.I.N.A., Green Swamp Server, PHD2, Adobe Photoshop CC, Pixinsight.
Dog and best bud: Jack
Sky: Bortle 6-7
My Astrobin: https://www.astrobin.com/users/Juno16/
- Larry 1969
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Re: Is this vignetting?
I was confused with the processing process. I was using the wipe module to bring out the stacking errors then cropping...
I have a better understanding now. Thanks for all the help and patience!
Larry
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
- Star Dad
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Re: Is this vignetting?
Orion 203mm/f4.9/1000mm, converted TASCO 114mm/f9/1000mm to steam punk, Meade 114mm/f9/1000, Coronado PST, Orion EQ-G, Ioptron Mini-Tower and iEQ30, Canon 70D, ASI120MM,ASI294MC, Ioptron SkyHunter
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