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What level of clarity should I expect when viewing Jupiter? 8" Orion Newtonian

beginner collimation planet
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#1 adhamh

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Posted 20 January 2019 - 01:29 PM

Hi,

 

I don't know what I should expect in terms of clarity.  I have an 8" Orion Dobsonian scope and this morning when I was viewing Jupiter with my Vixen SLV 5mm eyepiece.   I couldn't get it 100% in focus.  I think this could due to seeing conditions, poor collimation and the factory focuser not being great.  

 

I'm really not sure how in focus I was should be able to get a big planet like this.  Should it be as sharp as the NASA photos or will it always be a little more blurry than that?

 

Thanks!


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#2 Cajundaddy

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Posted 20 January 2019 - 01:34 PM

It does indeed depend on your seeing conditions, altitude above the horizon, collimation, and magnification.  Right now the planet is still pretty low but rising.  On a good night I will get moments of very clear views up to about 200x but often it is blurred and jumping around a bit due to atmospherics.


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#3 havasman

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Posted 20 January 2019 - 02:01 PM

It's never going to look like the NASA photos. But it's no fault of the scope. that's just the way it is.

 

It will look VERY good! Viewing Jupiter this time of year is a compromised exercise. Everything is bebst observed at meridian. But don't let that stop you if that's what you want to see. Observing closer to the horizon gives you much more atmosphere to peer through and that just magnifies the negative effects it presents as it washes through the extended optical path, carrying pollutants, dust, moisture and all that other content.

 

Collimation is absolutely critical. And easy. You have to know it's spot-on before you can expect your Newtonian scope to perform well. No way around it.

 

But you'll get those nights or moments when everything clicks and your scope will become a wonderful planetary instrument. Hang in there. Keep trying. work on your technique and enjoy the views.

 

One question: Does your scope focus well on other objects such as the moon and bright open clusters?


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#4 photomagica

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Posted 20 January 2019 - 02:03 PM

Carefully collimate your telescope and try again with about a 150x eyepiece. Add power only if seeing is good at this lower power. The factory focuser is likely OK - perhaps annoying but with a bit of patience it should let you get good focus.

 

Also, make yourself comfortable when observing and take your time. This is especially important on planets. I like to sit on a stool. This steadies my whole body and makes it easy to patiently wait for moments of good seeing. The eye takes awhile to attune to looking at a planet and I find I get my best views after observing for 10 or 20 minutes. The cheap folding stool I bought at Walmart is my favorite observing accessory. It makes my telescope and all my eyepieces twice as good!

 

Will what you see ever look like NASA photos? Not unless you buy yourself a Hubble space telescope or a planetary probe.  That said it is quite remarkable what can be seen in an amateur telescope. It is different, but special because it is just you, the telescope and your personal experience with the real light from the planet.

 

Let us know how it goes.

Bill


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#5 MikeTahtib

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Posted 20 January 2019 - 02:26 PM

I have only had one really good view of Jupiter.  Usually, it is a disc with a few hazy bands.  One morning, though, with my 8", I could see swirls within the bands.  They came in and out of focus constantly, so I had to watch it for those moments when the detail really popped out.  I live about 25 miles from the ocean, at an altitude of about 200ft.  When I look up my sky condition forecast on the ClearDarkSky website, seeing is almost always bad or poor, unless the night is overcast.  So I conclude my difficulty seeing planetary detail is mostly due to bad seeing conditions, rather than optical flaws with my telescopes.  


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#6 sg6

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Posted 20 January 2019 - 04:47 PM

It will be relatively small and often not "sharp".

Atmosphere causes problems and the newtonian secondary adds in a bit more. If it was low then you are looking through a wedge of atmosphere not a flat chunk and that adds in to it all.

 

My one good view was through a small achro refractor, I was trying out some new eyepieces, and Jupiter was convenient. Slight catch was it was small, very small, but good. Later this year I will try with a bigger achro - Tal 100RS, may even try the Megrez 90.

 

Think the better time will be around mid June this year. Saturn hits its best a month later for us.



#7 Sketcher

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Posted 20 January 2019 - 05:04 PM

I prefer to approach my observations without expectations.  Then, each session is a bit like a child slowly opening a gift-wrapped present.  I never know what I'll see and what I'll not see.  The more time I spend looking, (especially if I also take the time to work on a sketch) the greater my odds are of seeing more.  Yet, sometimes conditions get worse, and I end up seeing less!

 

Every night is different.  Jupiter rotates, presenting different faces at different times.  Jupiter's features are constantly changing.  Seeing conditions change.  The telescope's performance can change.

 

A planet like Jupiter requires patient study and experience in order to approach seeing all that the more experienced observers can see -- even when they're using smaller telescopes.

 

Happy observers are those who observe without expectations.  They're happy to see whatever it is that they see; and they know that patience and persistence has its rewards.

 

There are too many variables to predict what you should or should not see when you're observing Jupiter.  Keep looking.  Experiment with whatever you may have to experiment with.  Discover what works best for you.  That which works best for me may not work so well for you.

 

Visual astronomy is a journey in discovery -- not just the discovery of stars and planets, but also discovery of one's self and one's capabilities.  Looking at (studying) Jupiter through a telescope is far different than looking at any photograph or image of the planet!


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#8 JoeInMN

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Posted 20 January 2019 - 09:16 PM

I second all comments re: the importance of collimation; nothing else will matter if this isn't right. It's not really hard to do, but does take a bit of practice and patience. Equally important is giving the scope enough time to cool down when you take it outside. Until your mirror's core and surface temperatures even out enough, its figure will be altered enough to throw the image out of whack, and warmth coming off of the mirror will create thermal currents in your tube as well. Don't start out with the high magnification; use lower power first, and bump it up gradually as the seeing allows. Don't expect an eyepiece-filling view of the Red Spot. Yucky seeing can be the issue, and of course there's nothing you can do about that except wait for a better night, short of moving to a mountaintop or something. And, once you have everything aligned and cooled down under a decent sky, observation itself takes practice. In average seeing, the image quivers and blurs in and out of focus, and details that appear in those instants of clarity sort of accumulate in your brain, and your ability to see those details improves with time. I'm probably not describing this in the best way, but that's how it seems to work.


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#9 Jon Isaacs

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Posted 21 January 2019 - 10:15 AM

Lots of good advice so far. 

 

I just want to stress the importance of stable seeing.  Currently Jupiter is low on the eastern Horizon on the early morning.  One is looking through a great deal of air, it's very likely unstable air so the views are unlikely to be crisp.. 

 

For observers in the northern hemisphere,  Jupiter is not well situated this time. From 32 degrees north, Jupiter reaches about 35 degrees elevation.  From 45 degrees,  only about 23 degrees. 

 

Ideally, an elevation 45 degrees or more is desired,  30 degrees can be decent, 20 degrees rarely is. 

 

Jon



#10 adhamh

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Posted 23 January 2019 - 11:14 AM

It's never going to look like the NASA photos. But it's no fault of the scope. that's just the way it is.

 

It will look VERY good! Viewing Jupiter this time of year is a compromised exercise. Everything is bebst observed at meridian. But don't let that stop you if that's what you want to see. Observing closer to the horizon gives you much more atmosphere to peer through and that just magnifies the negative effects it presents as it washes through the extended optical path, carrying pollutants, dust, moisture and all that other content.

 

Collimation is absolutely critical. And easy. You have to know it's spot-on before you can expect your Newtonian scope to perform well. No way around it.

 

But you'll get those nights or moments when everything clicks and your scope will become a wonderful planetary instrument. Hang in there. Keep trying. work on your technique and enjoy the views.

 

One question: Does your scope focus well on other objects such as the moon and bright open clusters?

Thanks!  Yes, I can get very good focus on the moon.  I have not tired viewing other things yet.



#11 adhamh

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Posted 23 January 2019 - 11:17 AM

Carefully collimate your telescope and try again with about a 150x eyepiece. Add power only if seeing is good at this lower power. The factory focuser is likely OK - perhaps annoying but with a bit of patience it should let you get good focus.

 

Also, make yourself comfortable when observing and take your time. This is especially important on planets. I like to sit on a stool. This steadies my whole body and makes it easy to patiently wait for moments of good seeing. The eye takes awhile to attune to looking at a planet and I find I get my best views after observing for 10 or 20 minutes. The cheap folding stool I bought at Walmart is my favorite observing accessory. It makes my telescope and all my eyepieces twice as good!

 

Will what you see ever look like NASA photos? Not unless you buy yourself a Hubble space telescope or a planetary probe.  That said it is quite remarkable what can be seen in an amateur telescope. It is different, but special because it is just you, the telescope and your personal experience with the real light from the planet.

 

Let us know how it goes.

Bill

Yes, a chair is a must have.  My back...

 

I'll keep practicing the collimation.  I'm not doing it right before every viewing with is something I should start doing.



#12 adhamh

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Posted 23 January 2019 - 11:20 AM

Thanks to everyone for the good advice.  I think my collimation is questionable, but the seeing conditions were the biggest issue.  Over the summer when Jupiter was high I did get better views, so that dang atmosphere is definitely an issue...


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#13 Miranda2525

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Posted 23 January 2019 - 05:45 PM

Hi,

 

I don't know what I should expect in terms of clarity.  I have an 8" Orion Dobsonian scope and this morning when I was viewing Jupiter with my Vixen SLV 5mm eyepiece.   I couldn't get it 100% in focus.  I think this could due to seeing conditions, poor collimation and the factory focuser not being great.  

 

I'm really not sure how in focus I was should be able to get a big planet like this.  Should it be as sharp as the NASA photos or will it always be a little more blurry than that?

 

Thanks!

Right now Jupiter is far too low to get any good views. Wait until it gets higher in the coming months. This years apparition isn't a favorable one, as it doesn't get really high anyways.


Edited by Miranda2525, 23 January 2019 - 05:45 PM.


#14 hamishbarker

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Posted 24 January 2019 - 04:24 PM

For an idea of how bad seeing can be, next time it's really windy look at a bright star at medium to high power. It can be so bad it looks more like a globular cluster than a star!

#15 Deep13

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Posted 25 January 2019 - 04:33 AM

Most likeky the peoblem is thermals. That scope has no ventilation around the mirror, so it takes a long time to cool off. As it cools, warm air runs off the mirror face and up the inside of the tube, causing turbulence.

#16 MikeHC8

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Posted 28 January 2019 - 09:22 PM

Some one said look at it for 10 or 15 minutes at a time, also give your eyes 20 minutes to adjust to night sky.  I agree so much with chair, and for big times have a back also with the chair.  I'm still newbie but I feel a adjusted scope then comfort 2nd.  Just relax, so much to learn.  I just excited just to see planets and trying to make out details.  I feel practice and practice and never give up, I was lucky in Colorado with clear steady sky, you'll will never forget it when it happens.



#17 MikeBOKC

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Posted 29 January 2019 - 08:57 AM

Jupiter is just very sensitive to seeing conditions, because there is so much detail there. As some have noted it pays to be patient and observe for a while; it tends to come in and out of clarity as atmospheric conditions change. The key thing to remember about Jupiter is that you are dealing with two atmospheres here, ours and its. Other than during Mars opposition for a  brief time, that is not true of any other telescopic target.

 

Another tip I learned long ago was to focus on the moons and not the planet. Get them as clear discs and you will won't be futilely trying to chase focus on the planet.



#18 penguinx64

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Posted 12 February 2019 - 12:15 PM

Maybe try lowering magnification to 150-200x with an eyepiece between 8-6mm?  Sometimes lower magnification helps with Jupiter.  I've seen some bad nights where anything over 90x was too much.  I like 195x for Jupiter on a good night.



#19 Steve Cox

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Posted 13 February 2019 - 07:35 PM

As about everyone  above has mentioned already - seeing, cooldown, collimation.  And even when seeing is excellent, I have trouble if the planet is directly above a neighbor's roof, especially in the summer where thermal radiation and even airflow from A/C units interfere and reduce "seeing" in that one area by a factor of 2-3 on the Pickering scale.

 

I'll also echo what Felix directly above states, reduce magnification.  Unlike the Moon and other planets, Jupiter is (to me) very sensitive on magnification.  Anything above around 1 exit pupil for a given scope (or stated more simply - eyepiece focal length is the same as the given scopes focal ratio) softens the views I get on Jupiter.  For my 6" f/8 refractor, I seldom use eyepieces shorter than my 6mm; for my f/10 C90, usually nothing shorter than 9mm.

 

edit - 

The best view I've ever had of Jupiter with any of my former scopes was with my old 12" f/5, where I could easily use a 4mm eyepiece without the scope even "breathing".  375X was easy in that scope on even a halfway decent night.

 

To the OP - I would estimate a 6mm eyepiece would be the most you'd want most nights for your 8" f/6, and maybe a good 4mm on the very best of nights and conditions.


Edited by Steve Cox, 13 February 2019 - 07:40 PM.


#20 phillip

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Posted 13 February 2019 - 08:35 PM

All is well covered.

Be sure and check for the GRS Great Red Spot when rotates to view. Decent conditions easy.

Also Jupiter's lunar shadow transits I never tire catching.

It is abit low for best view, but reasonable conditions should bring above in view near easily.

Enjoy it's a fun Watch!

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