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Suggestions on getting better at imaging Jupiter

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#76 Lopper

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Posted 05 October 2021 - 01:23 PM

Rehling makes some very good points about local seeing effects. We might not be able to control the jet stream (yet), but we can exert some control over thermal issues closer to the ground. I've been seen on more than a few midsummer evenings spraying down my driveway with the garden hose at dusk in a (probably vain) attempt to cool the concrete a bit so it doesn't spend the entire night radiating its heat up around my scope. And if I have to point directly above a neighboring rooftop to image the planets I can tell from the on-screen view that I'm looking through more turbulence than if I move my scope to the other side of my driveway so I can image above grass, some trees, and a field. And something above my SW horizon really wreaks havoc on my seeing. No idea what it is...could be the next city over for all I know, but in that patch of sky things always look worse. Move away a bit in any direction and the seeing usually looks better.

 

Matt


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#77 HarveyDeckAstro

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Posted 05 October 2021 - 06:25 PM

That’s a good point. In NJ because of the trees my only view of Saturn and Jupiter is above my own roof, and barely clearing it. This is definitely limiting and may deny me any good seeing. I have now moved my scope to a central Pennsylvania location where I need to go for work fairly frequently. The sky is much more open and the houses are more spread out. I don’t have the scope at NJ and will miss a lot of clear nights, but this hopefully will improve the seeing when I do get clear skies at PA. Also helps with family life, wife would not complain about me fiddling with the scope all night when I am at PA :-)

#78 Cfeastside

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Posted 05 October 2021 - 09:48 PM

Very helpful thread. Thanks for sharing the knowledge!


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#79 HarveyDeckAstro

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Posted 07 October 2021 - 05:11 PM

So last night was unexpected clear night at the Central Pennsylvania location. I reconfigured the Barlow such that f ~ 20. Used the ZWO ADC. Maximum frame rate I could get was 140 fps with FireCapture on my macbook air, so I went with that. Gamma was turned off during capturing. The seeing was rated 4 in meteoblue. Really spent time focusing on features on Jupiter. Shot six videos of two minutes, 20% stacked and combined with derotation. More details seem come out this time around, and I am happy smile.gif

 

Thanks all for guiding me through the quest of getting better images of Jupiter! Hopefully I will progress more with practice.

 

Harvey

 

 

Attached Thumbnails

  • 2021-10-06-0118_54-Jupiter_Derotated_PS.jpg

Edited by HarveyDeckAstro, 07 October 2021 - 07:44 PM.

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#80 HarveyDeckAstro

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Posted 14 October 2021 - 09:10 AM

Last night was unexpectedly clear. Despite the seeing was reported to be 2/5 with jet stream 30m/s, I had to image! There was span of 10 minutes of relatively good seeing. Here is Jupiter with the GRS during that span, 4x2 minutes vids, 20 percent stacked, deroated.

 

Learned to go light on sharpening. Again spent a lot of time working on ADC and focusing. This time the 1.5X Barlow was screwed on to the nose piece of ADC, but still the overall f ~ 20. This allowed the ADC to be between the Barlow and the camera.

 

This has been a productive season of working on Jupiter. It is time to go back to DSO smile.gif

 

Harvey

Attached Thumbnails

  • 2021-10-14-0137_01-Jupiter_Derotated_PS-low-light.jpg

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#81 matt_astro_tx

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Posted 14 October 2021 - 09:17 AM

Now THAT'S a great image.  You've come a long way.  Well done!


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#82 HarveyDeckAstro

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Posted 14 October 2021 - 09:43 AM

Thanks Matt! This was only possible with the help of the CN members in this thread!

#83 Foc

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Posted 14 October 2021 - 10:07 PM

Much nicer edges!    If  I was to be fussy I would say your post No. 80 Jupiter looks a little oversaturated to me (and I am almost always guilty of applying a bit too much lipstick on my own gas giants) such that its colors are a bit too...um... red I think.  But is is definitely an image with attitude and a big improvement  from the early ones.  I have a friend who has been imaging for over a year and he would be very happy to get that result even when the seeing is decentish.

 

Don't worry overmuch about seeing prediction, attached is last nights Meteoblue 8/10 predicted seeing for my location!  Since it has been storming for days I only had the scope out to test a new saddle and some other gear but the image  serves as an example of trusting to the star twinkle  which was rapid (or the satellite view which showed a stream of fast moving cloud) rather than the seeing model.  Apologies  to those who have just eaten and who view  this image, I should have reduced it to 50% capture size to match its low resolution but I just want to make the point of not waiting until you get green lights on your seeing models unless you are lucky and have a model that is very well matched to your location.

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  • poor seeing 2a.jpg

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#84 CrazyPanda

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Posted 14 October 2021 - 10:21 PM

Meteoblue is way off for my location. Every time it says local seeing conditions are 5 and 4, the seeing is meh. Meanwhile, I frequently get great views (and images) when it says seeing is 3 and 1 (but also get very bad views and images when it says the seeing is 3 and 1).

The speed of the jet stream is often the most reliable indicator of bad seeing. No matter how good local seeing is, if the jet stream is above 30, there is almost always a limit to detail I can see and capture.

 

But there's no substitute for just going out every clear night and doing as long of an imaging session as possible. You might get 15 captures, and maybe one is good.


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#85 HarveyDeckAstro

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Posted 15 October 2021 - 08:43 AM

I will tone down the saturation:-)

Indeed, I find the predictions of seeing in medeoblue questionable. It is fun to imaging no matter what, and often there are brief quiet periods.
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#86 Achernar

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Posted 15 October 2021 - 05:28 PM

You can get good images with an 8-inch, but you need to limit recordings to one or two minutes at most due to the rapid rotation of the planet. Check the instructions to see what the size of the camera's pixels are in microns, you want to use an effective focal ratio no more than about five times the size of the camera's pixels. Any greater only extends exposure times, reduces and frame rates, increases noise due to the use of high gain settings, all with no increase in resolution. I use a ZWO 290MC camera which has 2.9 micron pixels on my 8-inch SCT, and to get the optimum image scale possible with this telescope, I use an Antares 1.5X Barlow with that camera, and a 3X Barlow with my ZWO 174MM monochrome camera because it's pixels are 5.8 microns wide. Therefore the effective focal ratios are F/15 and F/30 respectively. Use a small  area of the chip to speed up the frame rate, and use your histogram function in the capture software to adjust the exposure time and gain to get a maximum brightness value between 60 and 80 percent. Use the USB 3.0 port if your computer has one. If you have a laptop with a solid state drive, use that because it can record video faster. You should be able to reach 150 fps on Jupiter and 50 fps on Saturn. Faster frame rates are beneficial, but watch the gain. Don't overdo it because the noise that causes will appear after sharpening. Also, get an atmospheric dispersion corrector if you don't have one. The atmosphere causes color fringing because it acts like a weak prism, and an ADC removes it.

 

Taras


Edited by Achernar, 15 October 2021 - 05:29 PM.

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#87 Achernar

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Posted 15 October 2021 - 05:42 PM

You can get good images with an 8-inch, but you need to limit recordings to one or two minutes at most due to the rapid rotation of the planet. Check the instructions to see what the size of the camera's pixels are in microns, you want to use an effective focal ratio no more than about five times the size of the camera's pixels. Any greater only extends exposure times, reduces and frame rates, increases noise due to the use of high gain settings, all with no increase in resolution. I use a ZWO 290MC camera which has 2.9 micron pixels on my 8-inch SCT, and to get the optimum image scale possible with this telescope, I use an Antares 1.5X Barlow with that camera, and a 3X Barlow with my ZWO 174MM monochrome camera because it's pixels are 5.8 microns wide. Therefore the effective focal ratios are F/15 and F/30 respectively. Use a small  area of the chip to speed up the frame rate, and use your histogram function in the capture software to adjust the exposure time and gain to get a maximum brightness value between 60 and 80 percent. Use the USB 3.0 port if your computer has one. If you have a laptop with a solid state drive, use that because it can record video faster. You should be able to reach 150 fps on Jupiter and 50 fps on Saturn. Faster frame rates are beneficial, but watch the gain. Don't overdo it because the noise that causes will appear after sharpening.

 

Taras



#88 HarveyDeckAstro

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Posted 22 October 2021 - 05:28 AM

Yes, I am doing most of these things now. It appears that 3 minutes is still fine for Jupiter; AS3 can handle the amount of rotation. There is a recent thread about it on this forum.

#89 dcaponeii

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Posted 22 October 2021 - 06:48 AM

There have been lots of threads on duration of videos for Jupiter. Three minutes is reasonable even with my 12”. Restricting yourself to less than 2 minutes will limit the number of frames to work with during stacking.
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