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Saturn at opposition from San Diego, CA, August 2, 2021

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#1 Tom Glenn

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Posted 03 August 2021 - 02:44 AM

This is my first planetary image in quite some time.  In fact, one would have to go back over two years to July of 2019 to find my last dedicated image of Saturn, although I did image the Great Conjunction with Jupiter last winter.  Alas, limited time and perpetual cloud cover at night in coastal California has precluded me from most imaging.  However, I was lucky to obtain a clear night last night during the opposition of Saturn.  Often times these clear nights are associated with horrible seeing, but on this occasion the conditions were completely acceptable, albeit not perfect.  This image was taken approximately 3 hours after the moment of opposition, and the surge in ring brightness (Seeliger effect) is quite evident.  Saturn was 34 degrees altitude at the time of the image, which gives great promise for those of us in the northern hemisphere in the years to come as the planet continues to rise slowly.  The image was taken with a C9.25 Edge HD and ASI224mc, with a 2x TeleVue barlow and ZWO ADC.  The first version below is resized to 67% of capture scale, and the second version is 100% capture scale.  Due to spacing issues with the barlow and ADC, the original image scale is beyond the level typically supported by this aperture, however in this case it holds up well depending on your monitor and viewing conditions.  

 

Saturn-opposition-August-2-2021-TGlenn-small.jpg

Saturn-opposition-August-2-2021-TGlenn-large.jpg


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#2 Foc

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Posted 03 August 2021 - 03:46 AM

Good result Tom!



#3 Kokatha man

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Posted 03 August 2021 - 04:08 AM

Excellent Tom - & only 34°..! waytogo.gif waytogo.gif waytogo.gif Worth going inside & putting my glasses on! :) 


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#4 moonwatching ferret

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Posted 03 August 2021 - 05:07 AM

looks great I got clouded but  did get Saturn on the 1st



#5 Lopper

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Posted 03 August 2021 - 09:04 AM

Fantastic image, Tom! I'm still trying to get a Saturn image that good from my C9.25.



#6 Dan4.669

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Posted 03 August 2021 - 09:47 AM

Well done!



#7 RickD_99

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Posted 03 August 2021 - 10:06 AM

Fantastic Tom….uber inspiration for this C9.25 owner!



#8 Tom Glenn

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Posted 04 August 2021 - 03:00 AM

Many thanks for the comments Ross, Darryl, Ferret, Matt, Dan, and Rick.  Much appreciated!  It felt good to see Saturn again, and to get a reasonable result.  Because of convenience, I do the vast majority of all imaging from home, and one of the issues with the low elevation planets is that I only have a short window of opportunity on any given night because of various obstructions (houses, trees, fences).  Things start to get much better once an object rises above 55 degrees, because from my yard this opens up many more lines of visibility without obstruction.  Unfortunately, Saturn still has a ways to go to get there, although I believe Jupiter gets close to that elevation for me starting next season.  


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#9 kevinbreen

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Posted 04 August 2021 - 07:13 AM

Colours are terrific, Tom, as are the images themselves. Are your enhancing the vibrance and/or saturation in photoshop or similar once sharpened? Asking for a friend - I'm just happy for the moment to capture detail from undersampled IR captures!

#10 Tom Glenn

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Posted 05 August 2021 - 04:25 AM

Colours are terrific, Tom, as are the images themselves. Are your enhancing the vibrance and/or saturation in photoshop or similar once sharpened? Asking for a friend - I'm just happy for the moment to capture detail from undersampled IR captures!

Thanks Kevin.  Yes, I am adding some saturation and vibrance in Photoshop, although I attempt to keep it somewhat "normal" without diving too far off the deep end with exaggerated colors, although that is open to personal interpretation.  Tomorrow I will try to add another post describing some of the raw data.


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#11 Tom Glenn

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Posted 06 August 2021 - 02:51 AM

OK, so I wanted to provide a brief summary of the data, with an eye towards giving people with similar equipment a realistic set of expectations.  Because scopes of this size are very common, I frequently get questions and comments from people with similar equipment asking about capture details, especially since I am also dealing with the common problem of low elevation planets for us Northern Hemisphere imagers (although admittedly San Diego is better positioned that most U.S locations, outside of Florida and Hawaii).  There are certainly technical aspects that one must master, but also the seeing has to at least be good enough, or else you are dead in the water before you even start. 

 

There is a common misconception among many, but especially the relatively inexperienced, that there is some processing magic that can turn mediocre data into marvelous results.  This is simply untrue.  Although programs like Autostakkert are very sophisticated, it is universally true that the best images have high quality input data.  The best way to convey this is to simply look at the individual frames that comprise the raw data. 

 

With that in mind, consider the following.  I'm only going to focus on the raw data capture here, but keep in mind that the preparations, including collimation, thermal equilibrium, and focus, are all extremely important.  For this image, I used a shutter speed of 15ms for a frame rate of 66fps.  Gain was 400 on the ASI224mc, which is no problem, and the raw histogram was 50%.  I was at approximately f/30 because of the interaction between the ADC and the 2x barlow I use, which effectively makes it 3x.  I captured for 6 minutes duration, during which time I collected 23,989 frames.  Shown below is the quality graph from Autostakkert. 

 

Autostakkert_screen.jpg

 

The profile of the graph only gives a sense of the consistency of the seeing, not the quality.  You could have uniformly bad seeing that gives a graph profile that looks "good".  In this case, I knew from the live view that the seeing was pretty good, but not very consistent, which is shown in the graph.  So you have to look at individual frames.  Shown below are examples of good and bad raw frames, completely unprocessed aside from adjusting the white point of the image (to make it brighter) and performing an RGB balance in Registax to normalize the color.

 

Example of a good single frame---stack these!

Sat_good_f21377.jpg

 

Example of a bad single frame---avoid these!

Sat_bad_f09706.jpg

 

For this image, I had about 1000 frames that looked as good as the best example shown above, and so that is how many I stacked.  Deeper stacks also looked just fine, but no better in this case.  This will vary from capture to capture, and there is no set rule on how many to stack.  But you have to ask yourself whether your individual raw frames look more like the "good" example or the "bad" shown above.  If they look more like the bad, which is often the case, then there is nothing you can do to produce a good outcome.  So you then need to try and address what caused the bad frames, to determine if it is something that you can improve upon technically, or whether it was just bad seeing.  

 

After stacking the 1000 frames, this is the resulting stack, with no sharpening or other processing whatsoever, except for the aforementioned color balancing.  At this point, modest sharpening in any software (there are many options here) and a slight boost to color saturation is all that is needed to arrive at a very reasonable final result.  And keep in mind, this image I posted at the top of the thread is nowhere near the limitations of the scope, if only conditions were better, which will likely have to wait until Saturn rises higher in the sky for us Northerners.  And yes, an ADC is absolutely required, and will be for many years to come, likely until Saturn passes 70 degrees altitude, which for me will not happen for another 8 years.  

 

Raw stack---NO sharpening

Sat_022842-raw-stack-RGB-balance-TGlenn.jpg


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#12 dcaponeii

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Posted 06 August 2021 - 11:56 AM

OK, so I wanted to provide a brief summary of the data, with an eye towards giving people with similar equipment a realistic set of expectations.  Because scopes of this size are very common, I frequently get questions and comments from people with similar equipment asking about capture details, especially since I am also dealing with the common problem of low elevation planets for us Northern Hemisphere imagers (although admittedly San Diego is better positioned that most U.S locations, outside of Florida and Hawaii).  There are certainly technical aspects that one must master, but also the seeing has to at least be good enough, or else you are dead in the water before you even start. 

 

There is a common misconception among many, but especially the relatively inexperienced, that there is some processing magic that can turn mediocre data into marvelous results.  This is simply untrue.  Although programs like Autostakkert are very sophisticated, it is universally true that the best images have high quality input data.  The best way to convey this is to simply look at the individual frames that comprise the raw data. 

 

With that in mind, consider the following.  I'm only going to focus on the raw data capture here, but keep in mind that the preparations, including collimation, thermal equilibrium, and focus, are all extremely important.  For this image, I used a shutter speed of 15ms for a frame rate of 66fps.  Gain was 400 on the ASI224mc, which is no problem, and the raw histogram was 50%.  I was at approximately f/30 because of the interaction between the ADC and the 2x barlow I use, which effectively makes it 3x.  I captured for 6 minutes duration, during which time I collected 23,989 frames.  Shown below is the quality graph from Autostakkert. 

 

attachicon.gifAutostakkert_screen.jpg

 

The profile of the graph only gives a sense of the consistency of the seeing, not the quality.  You could have uniformly bad seeing that gives a graph profile that looks "good".  In this case, I knew from the live view that the seeing was pretty good, but not very consistent, which is shown in the graph.  So you have to look at individual frames.  Shown below are examples of good and bad raw frames, completely unprocessed aside from adjusting the white point of the image (to make it brighter) and performing an RGB balance in Registax to normalize the color.

 

Example of a good single frame---stack these!

attachicon.gifSat_good_f21377.jpg

 

Example of a bad single frame---avoid these!

attachicon.gifSat_bad_f09706.jpg

 

For this image, I had about 1000 frames that looked as good as the best example shown above, and so that is how many I stacked.  Deeper stacks also looked just fine, but no better in this case.  This will vary from capture to capture, and there is no set rule on how many to stack.  But you have to ask yourself whether your individual raw frames look more like the "good" example or the "bad" shown above.  If they look more like the bad, which is often the case, then there is nothing you can do to produce a good outcome.  So you then need to try and address what caused the bad frames, to determine if it is something that you can improve upon technically, or whether it was just bad seeing.  

 

After stacking the 1000 frames, this is the resulting stack, with no sharpening or other processing whatsoever, except for the aforementioned color balancing.  At this point, modest sharpening in any software (there are many options here) and a slight boost to color saturation is all that is needed to arrive at a very reasonable final result.  And keep in mind, this image I posted at the top of the thread is nowhere near the limitations of the scope, if only conditions were better, which will likely have to wait until Saturn rises higher in the sky for us Northerners.  And yes, an ADC is absolutely required, and will be for many years to come, likely until Saturn passes 70 degrees altitude, which for me will not happen for another 8 years.  

 

Raw stack---NO sharpening

attachicon.gifSat_022842-raw-stack-RGB-balance-TGlenn.jpg

Excellent discussion of the subject.  Thanks for taking the time.



#13 psugrue

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Posted 06 August 2021 - 01:18 PM

Thanks for the screen shots of AS3 and the detailed workflow.

 

Respect,

 

Patrick




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