Struggling to capture crisp Jupiter or Saturn images

Frequent contributor

Sep 8, 2023

How high was the planet when you took the images? Anything less than 30 degrees is very likely doomed to failure but you want to go at it when is as high as it can get. And seeing rules supreme with planetary imaging so if the seeing isn't good you're just wasting time. I mean really good, steady as rock good.

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Oskari Nikkinen

Sep 8, 2023

Are you using a barlow with this setup? Theoretical ideal sampling for planetary can be approximated to: Ideal f ratio = pixel size in microns x4. So in the case of your 3.76 micron it would be roughly f/15 so a 1.5x barlow needed. I am not math savvy myself so couldn't tell you exactly what reasoning was used to arrive to that conclusion, but some other math savvy people have so i trust that. But safe to say that you are probably a little bit undersampled if you are at f/10.

Other than that, you need frames, lots and lots of frames. Think in the tens of thousands rather than thousands. For best results you really ought to use a capture computer that is capable of supporting full USB3 speeds so that you can cram as much frames into a recording as possible.

Collimation needs to be better than perfect for ideal results as well. Very small issues lead to obvious loss of sharpness for planetary stuff. Another thing that cant be overlooked is focusing. You need to spend some time with focusing on the planet itself (not on the Moon, or on a star, or with autofocus but manually) to get the best results. You could spend half or more of your time racking the focuser in and out in search of that perfect micron small spot where the planet is at its sharpest. This is tricky if the seeing is not very good, because your focus will go in and out with seeing.

And one more thing, the elevation of the planet needs to be as high as possible for best results. Below 30 degrees we start to see serious issues and below 20 degrees will be very difficult. Ideally the planet should be as high as it can possibly be.

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Sep 8, 2023

The first problem is drizzle 3x. Get rid of it. I had the exact same problem and it completely went away when I stopped using drizzle. Image became much sharper, even when I end up resampling x2 or x3. The second problem is you need to use a barlow for approriate sampling. Ideal f ratio would be F/18.5, so a 2x barlow bringing you up to f/20 would work well.

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Norman Tajudin

Sep 9, 2023

I would agree with Alan that seeing is everything. I have an incredible Maksutov with high magnification (f/15) but I live at sea level here in Huntington Beach, California. I have now accepted that I can't try to capture at that magnification given that I'm punching through a lot of turbulent air. I can't wait to take it out to some dark sky locations in the future though…

Clear skies,

HBNorm

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Topic starter

Sep 9, 2023 · Edited: Sep 9, 2023

andrea tasselli:
How high was the planet when you took the images?

about 25° - my current max at 52N latitude -
plus turbulences that the video would dance.

So you mean I was doomed anyway and did not make major mistakes?
Frustrating but somewhat comforting ... Thanks !

Arny

Topic starter

Sep 9, 2023

Ashraf AbuSara:
The first problem is drizzle 3x. Get rid of it. I had the exact same problem and it completely went away when I stopped using drizzle. Image became much sharper, even when I end up resampling x2 or x3. The second problem is you need to use a barlow for approriate sampling. Ideal f ratio would be F/18.5, so a 2x barlow bringing you up to f/20 would work well.

I tried without drizzle, but no difference, the 320p solutions just were too small. But resampling is a good idea.

Barlow I did not dare for the worse f-ratio - I am already at 0.28"/pixel.
What would it help to go down to 0.14"/pixel?

Topic starter

Sep 9, 2023

Oskari Nikkinen:
Theoretical ideal sampling for planetary can be approximated to: Ideal f ratio = pixel size in microns x4. So in the case of your 3.76 micron it would be roughly f/15 so a 1.5x barlow needed. I am not math savvy myself so couldn't tell you exactly what reasoning was used to arrive to that conclusion, but some other math savvy people have so i trust that. But safe to say that you are probably a little bit undersampled if you are at f/10.

Thanks for your advice.
Even though I don't get, why f/10 is too little, I buy that many of you know from experience :-)

Focus is indeed painful and close to impossible with bad seeing. Good to know that manual beats auto- or starfocus - taking half an hour or more was necessary.

Topic starter

Sep 9, 2023

D. Jung:
Did you remove the protective film from the telescope?

Indeed I thought of something like that :-)

Frequent contributor

Sep 9, 2023 · Edited: Sep 9, 2023

Arny:
Barlow I did not dare for the worse f-ratio - I am already at 0.28"/pixel.
What would it help to go down to 0.14"/pixel?

Not one bit. In fact it would have made it worse. Stick with Jupiter this season (and the next and the next too). Look at the thing with an EP at high magnification (>300x) and if it looks steady for more than a fraction of a second then have a go at it. I'd recommend no more than 14"/px in the best of seeing and less if seeing isn't great (but at least decent).

Sep 9, 2023 · Edited: Sep 9, 2023

Ashraf AbuSara:
The first problem is drizzle 3x. Get rid of it. I had the exact same problem and it completely went away when I stopped using drizzle. Image became much sharper, even when I end up resampling x2 or x3. The second problem is you need to use a barlow for approriate sampling. Ideal f ratio would be F/18.5, so a 2x barlow bringing you up to f/20 would work well.

I tried without drizzle, but no difference, the 320p solutions just were too small. But resampling is a good idea.

Barlow I did not dare for the worse f-ratio - I am already at 0.28"/pixel.
What would it help to go down to 0.14"/pixel?

The optimal focal ratio for planetary imaging is dependent on two things, your camera's pixel size and your seeing conditions. Typically for good seeing you need to aim for 5x your pixel size. If you seeing was not really that good then 3x the pixel size, and for exceptional seeing you can go upto 7x your pixel size.

This FAQ is really helpful and helped me a lot.

https://www.cloudynights.com/topic/812022-planetary-imaging-faq-updated-january-2023/

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Sep 9, 2023 · Edited: Sep 9, 2023

andrea tasselli:
Arny:
Barlow I did not dare for the worse f-ratio - I am already at 0.28"/pixel.
What would it help to go down to 0.14"/pixel?

Not one bit. In fact it would have made it worse. Stick with Jupiter this season (and the next and the next too). Look at the thing with an EP at high magnification (>300x) and if it looks steady for more than a fraction of a second than have a go at it. I'd recommend no more than 14"/px in the best of seeing and less if seeing isn't great (but at least decent).

I do not agree with this advice. I think the point here is to help them image Saturn, not to dissuade them from imaging it (or worse, tell them to wait years). I took this image only 3 weeks ago with the 533mc pro which has the exact same pixel size, and a 2x Barlow using a C11 XLT at F20. This in fact was my first attempt.

I am by no means an expert, but if I can take this image I think the OP can do just as well if not better assuming their seeing conditions are not terrible.

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Frequent contributor

Sep 9, 2023

You took that image from Southern Texas, right? What is the latitude of So.Texas, pray? I bet it isn't 52deg N. For us fellas from up North Saturn is no go zone for the next 2 years at a minimum.

Sep 9, 2023

andrea tasselli:
You took that image from Southern Texas, right? What is the latitude of So.Texas, pray? I bet it isn't 52deg N. For us fellas from up North Saturn is no go zone for the next 2 years at a minimum.

A quick search of Astrobin for folks imaging from Germany just 13 days ago this season using a C8 and a 2x Barlow from Dusseldorf:

https://www.astrobin.com/ccze18/

Frequent contributor

Sep 9, 2023

One lucky shot won't change the general outlook: Saturn isn't worth a go for high Northern latitudes, especially so for someone like the OP which isn't experienced in planetary imaging. So they shouldn't feel bad if their attempt resulted in frustration. It is the expected outcome.

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Sep 9, 2023

andrea tasselli:
One lucky shot won't change the general outlook: Saturn isn't worth a go for high Northern latitudes, especially so for someone like the OP which isn't experienced in planetary imaging. So they shouldn't feel bad if their attempt resulted in frustration. It is the expected outcome.

I am not saying they should feel bad. I think those examples just demonstrate that there is perhaps some room for improvement. I will leave a link to the rest of the "super lucky shots" from Germany this season.

https://www.astrobin.com/search/?q=&d=i&subject=&telescope=&camera=&date_published_min=2023-06-11&date_published_max=2023-09-09&country=DE&subject_type=SATURN&sort=-published

@Arny
One other important point I forgot to mention is that collimation is critical according to the best ones that do this. That FAQ is extremely helpful.

Topic starter

Sep 9, 2023

Ashraf AbuSara:
A quick search of Astrobin for folks imaging from Germany just 13 days ago this season using a C8 and a 2x Barlow from Dusseldorf

thanks for the inspiration, Ashraf :-)

Topic starter

Sep 9, 2023

Ashraf AbuSara:
One other important point I forgot to mention is that collimation is critical according to the best ones that do this. That FAQ is extremely helpful.

it is really good - thanks for linking to it, Ashraf!
Especially the intro, that almost all that counts in DSO does not in planets opens the mind to reset :-)

Arny

Thomas W

Sep 9, 2023

I took this a couple days ago using a C8 from 52N. Saturn was at about 26 degrees in altitude. Decent seeing but very poor transparency. Not the best by any means but I am happy with it given the conditions.

It is entirely possible to get usable (very subjective term!) data through low altitudes, you just need to be patient for moments of good seeing as Saturn is not favourably placed. On that particular night seeing may just have been very poor for you. Needless to say there are a hundred other things to consider. For a start try and get a barlow to operate in the f18-20 region, increase exposure to the 10-40ms region, triple check collimation and do a star airy disk test, refocus fairly often, make sure the OTA has enough cooling time to equalise, make sure you are using a UVIR cut with that camera, use an ADC as improvements are significant at these altitudes, finally record lots and lots of data but only process the best.

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Sep 9, 2023 · Edited: Sep 9, 2023

Arny:
Ashraf AbuSara:
One other important point I forgot to mention is that collimation is critical according to the best ones that do this. That FAQ is extremely helpful.

it is really good - thanks for linking to it, Ashraf!
Especially the intro, that almost all that counts in DSO does not in planets opens the mind to reset :-)

Arny

Glad to hear that! That subforum in general has excellent and very experienced planetary imagers who are very helpful too.

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