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Markarian's Chain - Help

steviemac500

By steviemac500
in Imaging - Deep Sky

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steviemac500

steviemac500

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I've been collecting data for this target over 2 nights for a total of 9hrs. There are obvious issues with a gradient i am struggling to remove and some ringing which i think is from either the deconvolution or sharpening. My concern and what i'd like some help please is the vignetting in the corners i cant fix. I calibrated all frames with flats, the RGB subs came out well with no sign at all of this issue but the Lum has got really pronounced vignetting in the corners. I used a laptop and SGP to decide on frame exposure and using my camera's guide of 25000 full well went for 12500 ADU ( I have tried more - 25000/30000). I followed Mr keller's process through but i cant help but think there is something in the calibration i am missing. Any ideas?

 

Image05_DBE_registered.jpg

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Rodd

Rodd

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Do you have LP?  I know my Lum is much more sensitive to LP than my RGB.  Also--what software do you process with?  The corners look ok to me--if you study them I suppose you can spot some vignneting.  But I prefer to study the galaxies.  Nice image.

Rodd

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steviemac500

steviemac500

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7 minutes ago, Rodd said:

Do you have LP?  I know my Lum is much more sensitive to LP than my RGB.  Also--what software do you process with?  The corners look ok to me--if you study them I suppose you can spot some vignneting.  But I prefer to study the galaxies.  Nice image.

Rodd

Thanks Rodd. My back garden has very little LP, I'm lucky in that respect. I use PI to process. I just expected the flats to calibrate out the vignetting like they did with the RGB. I'm wondering if the moonlight had anything to do with it. 

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Rodd

Rodd

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5 minutes ago, steviemac500 said:

Thanks Rodd. My back garden has very little LP, I'm lucky in that respect. I use PI to process. I just expected the flats to calibrate out the vignetting like they did with the RGB. I'm wondering if the moonlight had anything to do with it. 

Did you by chance use ABE?  That always produces vignetting like artifacts.   DBE is far better.

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wimvb

wimvb

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That's a nice image with good framing. The target seems to fit your camera and scope very well.

It seems that you have some issues with the reducer/flattener; yu have distorted stars in the corners. The bottom left corner is clean and has nice stars. A closer look at the image's background also shows that you may have overdone the deconvolution. Adjusting the global dark deringing parameter and wavelet regularisation settings can help improve. Easiest way to remove the reflection (?) in the upper right corner is to crop. If you try to image this region again when the moon is out of the way, you can verify if it is/was a reflection.

Cheers,

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steviemac500

steviemac500

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6 hours ago, Barry-Wilson said:

I would suggest that the ADU setting is too low.  QSI for example recommend 35,000 for example, QSI web page.  I have regularly used 21,000 +/- 500 for my QSI and find my flats work well.

HTH.

Thanks Barry. I looked up the Moravian and the info I found said full well of 25000. I could be wrong though!!

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steviemac500

steviemac500

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7 hours ago, wimvb said:

That's a nice image with good framing. The target seems to fit your camera and scope very well.

It seems that you have some issues with the reducer/flattener; yu have distorted stars in the corners. The bottom left corner is clean and has nice stars. A closer look at the image's background also shows that you may have overdone the deconvolution. Adjusting the global dark deringing parameter and wavelet regularisation settings can help improve. Easiest way to remove the reflection (?) in the upper right corner is to crop. If you try to image this region again when the moon is out of the way, you can verify if it is/was a reflection.

Cheers,

Hi Wim, thanks for the comments. I'm pretty sure the distortion is caused by tilt. The stock focuser is not doing a great job of holding the Moravian but I have a moonlite ordered which hopefully will solve this.

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