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When drizzle integration works

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15 replies to this topic

#1 johnsoda

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Posted 23 October 2018 - 08:30 PM

Just finished drizzle integration on some undersampled data, and I think the below really shows its advantages in cases like this.  I don't think I need to identify which is before and which is after drizzling.  Details are 50 mm Sigma Art lens at f/4.0, ASI1600MM with Astrodon 3 nm Halpha filter, 104 subframes of 5 minutes each, gain of 76, CEM60EC, unguided. 

 

drizzle.png


Edited by johnsoda, 23 October 2018 - 08:34 PM.

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#2 johnsoda

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Posted 23 October 2018 - 09:11 PM

Here's a low-resolution version of the whole image - still tweaking it.

 

drizzle_integration_orion_small.png


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#3 APshooter

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Posted 24 October 2018 - 12:46 AM

Holey smoley!  That is one wide field.  Ironically I'm shooting the Horsehead as we speak, much tighter of course...



#4 tkottary

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Posted 24 October 2018 - 12:48 AM

Is this the canon version of sigma art?

#5 johnsoda

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Posted 24 October 2018 - 04:46 AM

Is this the canon version of sigma art?

Yes.



#6 johnsoda

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Posted 24 October 2018 - 05:48 PM

Full resolution available by clicking:

 

get.jpg?insecure


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#7 calypsob

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Posted 24 October 2018 - 08:10 PM

Very nice, how many hours integration?



#8 tkottary

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Posted 24 October 2018 - 08:16 PM

Yes.

thanks. Need to find a way to stop my Nikon lens.

#9 johnsoda

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Posted 24 October 2018 - 08:23 PM

Very nice, how many hours integration?

8.7



#10 Daniel Dance

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Posted 06 December 2018 - 06:07 AM

Hi  David,

 

Absolutely beautiful  image!!!

 

I'm working on a similar rig.  Can you comment on the following questions:

 

1.  I see you are using a 3nm H-Alpha filter.  Any reason you chose this over a less expensive 5nm astrodon?

 

2.  Can you comment a bit on your workflow of how you performed the drizzle integration and if there is anything you need to do during image capture to allow this?  Or is it post-processing only?

 

3.  And finally, what was your method for focusing the 50mm, especially when shooting the H-Alpha?

 

Thank you
Daniel


Edited by Daniel Dance, 06 December 2018 - 06:14 AM.


#11 Daniel Dance

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Posted 06 December 2018 - 12:15 PM

   David,

Can you also walk us through your processing workflow for this image?  Are you processing to reduce star sizes, etc... or is this pretty much how the image came out of the camera after it was stacked.

 

Thanks



#12 bobzeq25

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Posted 06 December 2018 - 04:44 PM

Lovely image.  Just a technical point.  The first image is 16 arc sec per pixel.  "Undersampled" is an understatement.  <smile>

 

Do you think not guiding is a substitute for dithering, in this case?


Edited by bobzeq25, 06 December 2018 - 04:48 PM.


#13 johnsoda

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Posted 08 December 2018 - 11:00 AM

Hi  David,

 

Absolutely beautiful  image!!!

 

I'm working on a similar rig.  Can you comment on the following questions:

 

1.  I see you are using a 3nm H-Alpha filter.  Any reason you chose this over a less expensive 5nm astrodon?

 

2.  Can you comment a bit on your workflow of how you performed the drizzle integration and if there is anything you need to do during image capture to allow this?  Or is it post-processing only?

 

3.  And finally, what was your method for focusing the 50mm, especially when shooting the H-Alpha?

 

Thank you
Daniel

1.  I've already learned that, assuming you will continue doing astrophotography, you're best off getting the best equipment you can reasonably afford, so you don't have to buy another one later.  The 3nm filter will support any future imaging I do.  I'm aware of the possible issues with narrow bandwidth filters at low focal ratios, but I think that's overblown unless you're operating at very low focal ratios.

 

2.  The workflow is pretty straight-forward.  I just do a regular integration, saving drizzle files, and then do a drizzle integration.  I do direct-mount dithering during acquisition when I don't guide.  I've found myself doing less and less processing as I go on.  Different strokes for different folks, but I prefer to have the images relatively raw and concentrate on acquisition, rather than processing.  For example, my favorite noise-reduction algorithm is more integration time. 

 

3.  Focus is probably one of the tougher things with my set up.  I find I stop and tweak it a bit at first, as the equipment temperature equilibrates, and then usually once more at the meridian flip.



#14 johnsoda

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Posted 08 December 2018 - 11:01 AM

   David,

Can you also walk us through your processing workflow for this image?  Are you processing to reduce star sizes, etc... or is this pretty much how the image came out of the camera after it was stacked.

 

Thanks

I don't process much at all, other than the usual calibration, registration, integration, drizzling, etc.


Edited by johnsoda, 08 December 2018 - 11:01 AM.


#15 johnsoda

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Posted 08 December 2018 - 11:03 AM

Lovely image.  Just a technical point.  The first image is 16 arc sec per pixel.  "Undersampled" is an understatement.  <smile>

 

Do you think not guiding is a substitute for dithering, in this case?

Well, unless you're doing a mosaic, undersampling is going to happen at these fields-of-view.

 

I do direct-mount dithering in SGP.  Honestly, I'm not sure it's absolutely necessary, but it takes very little effort and almost no time.



#16 johnsoda

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Posted 08 December 2018 - 12:10 PM

One bit of advice on the Sigma Arts lens:  it’s a fine lens, but, like many lenses, the coma is atrocious when at full aperture. It needs to be stopped down for decent astrophotography results. 


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