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AlphaOrionis

Ideal magnification to see jupiter's details/red spot?

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My telescope is struggling pushing 180x magnification, I make out the details but they are blurry. At 90x my image is very clear and sharp, but I can't make out the red spot. The telescope appears to have a limit of about 160x.

I'm about to buy a new eyepiece, and the best deal I can get right now is for a 128x. Will this be enough to make out details/red spot/moon shadows? Or should I try and find the ideal eyepiece that could push 150-160x to be safe?

Thanks!

Extra info:
ED80 80mm f/7.5 with a 6.7mm Explore Scientific and a 2x Televue Barlow (this gives me 90x and 180x)
Im looking at the ES 4.7, which would give me 128x

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You don't need really high powers to see these details. Good conditions and spending some time examining the planet will reveal them at around 120x - 130x or so.

As the aperture reduces so the ability to tease out the more subtle details becomes more challenging and I'd say that 80mm is going to mean that you need to work quite hard to see the Great Red Spot clearly but it should come as you get more experienced. The spot is often on the "wrong" side of the planet so not always visible from Earth.

Moon shadows are probably easier to spot than the GRS because, while small, they are strong contrast features against the surface of the planet.

Jupiter does not seem to respond to very high magnifications as well as, say, Saturn does so stepping down a little can often bring a more contrasty view albeit on a smaller scale.

 

 

Edited by John
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I was viewing with 91x magnification this past week and saw the moon's shadows when visible, the GRS and countless detail. Going to 150x made it a bit larger but the quality of image deteriorated. At about 250 - 300 x it was pointless viewing. 

John 

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When it's there, I can see the red spot at 111x. At that power it's possible to observe some details also. With the ES 4.7mm, 212x, I can get a great view most of the time, not always.

So I switch between 111x,  212x.

111x the view is always clean for Jupiter. (; 

Edited by N3ptune

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139x is always a winner for me.  A few days ago I collimated my 10" scope and 208 showed glimpses of sharpness on a night the weather seemed terrible for viewing. 

So I suppose:

Make sure your scope is aligned.

Use Stellarium or similar software to predict when the red spot will be visible.

Get a good eyepiece in that 128x - 140x range.

Try to catch Jupiter when it is high in the sky when there is less atmosphere between you and it to blur the image.

Get a comfy chair and get out there!

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Very large range of magnifications will allow you to see "detail", depends on what level of detail you expect or want. Also what you consider as "good" comes into it. Some people consider bigger with a little loss of sharpness as acceptable/better and others do not (myself). I have observed Jupiter down at magnifications around 50x or a bit less. I was testing the BST (Paradigm) 8mm out on a 350mm focal length achro.

This is likely the input concerning why a planetary observer will have eyepieces that alter in small increments. I would consider a good 4mm, 5mm, 6mm, 7mm, 8mm, 10mm then 12mm as required and that is on a 600mm focal length ED or TAL 100. One of them should deliver the balance between detail and scale that I like, or more correctly would find optimum at that observing session.

The scope is a factor also. Something like a CPC 9.25 with good eyepieces cooled and collimated will deliver a lot better then a Skywatcher ST 80 with the supplied eyepieces. If the scope is one of the Bird-Jones cheap designs then even less again I suspect.

 

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I was working at 110x max during the week and saw lots of detail including the GRS. I then tried at 180 and it started to go mushy.

The theoretical limit for small scopes is 2x aperture so the OP's set up would be OK for up to 160 in theory. Mine should be 400+ but I have never under UK skies been able to get that.

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Three nights in a row this week I managed very clear and sharp views of Jupiter including the GRS. This was with the 200 Dob and a WO 6mm EP giving 200 Mag. Stepping down to the BST 8mm giving 150 mag was quite stunning if a little smaller than the 6mm. I guess I was lucky with the seeing. Jupiter was really high in the sky and it wasn't quite astronomical twilight and I was getting plenty of moonshine from the moon

Edited by Sirius Starwatcher

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I am reading this thread and I wonder.. how in the world is it possible to watch Jupiter at 300x or 400x ? (With a clear view)


We know about the atmospheric conditions, they are bad in our regions (Canada and UK), there is the collimation factor for the instruments, the size of the instrument could play in the limitation. Also, we don't have an observatory on the top of a high plateau too like they have in South America.

--> But what if I get a good 18 inches reflector instead of a 8 inches one? will I be able to reach a super clear view at 212x for Jupiter? or even 300, 350x ? (Which is for me, impossible to get right now)

or

The bottom line is, and, considering the previous reasons 160x, 180x, ~200x, would be the usual limitation for all small telescopes ?

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You can get very clear detail at 300-400x but just have to wait longer and be quicker at 'seeing it' - imagers often use even more than this (or the equivalent). However, our eyes don't work like that and in general for visual astronomy, magnification is restricted to perhaps about 200x for Jupiter on all but a handful of special nights per year. A large aperture though even working at modest magnifications does in my experience provide more detail in fleeting moments of good seeing than a smaller aperture. With a smaller aperture you do get more time to tease detail out as the image is more stable so it's a bit swings and roundabouts really.

 

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1 hour ago, N3ptune said:

I am reading this thread and I wonder.. how in the world is it possible to watch Jupiter at 300x or 400x ? (With a clear view)


We know about the atmospheric conditions, they are bad in our regions (Canada and UK), there is the collimation factor for the instruments, the size of the instrument could play in the limitation. Also, we don't have an observatory on the top of a high plateau too like they have in South America.

--> But what if I get a good 18 inches reflector instead of a 8 inches one? will I be able to reach a super clear view at 212x for Jupiter? or even 300, 350x ? (Which is for me, impossible to get right now)

or

The bottom line is, and, considering the previous reasons 160x, 180x, ~200x, would be the usual limitation for all small telescopes ?

As has already been mentioned, seeing conditions dictate how high magnification you can go.

Another aspect is the scatter and floaters in our eyes. I've found I can generally use about 50% higher mag when binoviewing than in cyclops, the more relaxed eyes produce less scatter and floater, just as Nigel mentioned here

I've used 320x binoviewing in C8 in good seeings, the small festoons inside/near the main bands are much easier to pick out when the image is bigger.

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Ok (Sorry for the hijacking here, but it's interesting)

I will resume to this, viewing Jupiter at 300, 350x with my 203 x 1000 reflector is possible but rare. I will have to wait longer and be quicker at seeing the clear details. (I don't have anything to look at 300x right now so it's not possible to test but I see the explained point at 212x power, I wait and then the details are revealed for a few seconds.

The binoviewer can improve the situation in good seeing conditions in helping my eyes grasp the details so it's possible to push the magnification a little bit more.

Has for trading my 8 inches for a 18 inches, the 18 inches will improve the details on a clear day but I might have less stability over all to watch Jupiter ; but when it works it's rewarding.

===========
--> Is it common for people who have large dobsonians telescope (18, 20, 28 inches) to use power like 350, 400 x to watch Jupiter? or they are stuck at 200x most of the time?
 

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Is the lesson here that unless you are in a location with excellent seeing more than 200x magnification just is not going to be that useful?

Assuming so, does anyone have a good average "seeing conditions" map as opposed to a light pollution map which someone here linked me to an excellent one.

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I think there is something about the characteristics of Jupiter's surface features that means that very high magnifications, generally, just don't do the trick with it.

With Jupiter, the different features take the form of changes in contrast and tint. These changes are subtle rather than hard edged so throwing really high magnifications at them actually tends to make them less distinct rather than plainer to see.

Saturn seems to respond better to high magnifications when examining details in it's ring system because such features are marked by much less subtle contrast / brightness variations. Try and see atmospheric details (as opposed to shadow features such as the ring shadows) on the disk of Saturn itself and you find that they are much more elusive than Jupiters features so the high magnifications that are effective on ring features mask the much more subtle disk features.

It's all about understanding a bit about your subject and the conditions you are observing under and then having some options in your "toolkit" to experiment with to find which teases out what you want to see :icon_biggrin:

 

 

Edited by John

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I've often wondered if Saturn is easier to get higher magnifications with because the rings appear comparatively bright compared to the planet surface, yet Jupiter is very bright (high albedo) compared to its background. I've had some stunning views of Jupiter in twilight at around 180 - 200x (130mm aperture). Often I have difficulty at 100x at the moment. Mind you, I have been observing a lot with a 90mm Mak. I think to see any real detail on Jupiter you need at least 4".

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A seeing map or a list with average statistics for each country would be nice. (: I found 2 interesting maps searching for that: Cloud cover and Water vapor and I am simply trying to correlate famous observatory spots with these 2 maps, It seems like there is a link:

http://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MODAL2_M_CLD_FR&d2=MYDAL2_M_SKY_WV

Chile for example they have almost no clouds and water vapor has the map shows, they are on a special spot, maybe a special stream?

Hawaii: Less clouds then average and more vapor then Chile,

South pole: No clouds, no vapor

Australia Coonabarabran, same thing

===============

UK and Canada: Lots of clouds, not much vapor.

Some things are missing but.. it seems like there is a link.

Edited by N3ptune
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Another factor could be usable exit pupil size in relation to the object. On my f/12.7, 102mm Mak an 11mm and a 12mm Plossl would give me an 0.8mm and 0.9mm exit pupil respectively. I found that the nearer I got to a 1.0mm exit pupil the sharper Jupiter became at a magnification high enough to see detail. A 13mm eyepiece gave me 100x for about a 1.0mm exit pupil.

On my 90mm (f/11.3) Mak a 10mm EP will give 100x for a 0.8mm exit pupil, a 9mm EP will give 111x for a 0.7mm. I've seen the GRS (just about) at 111x although it helped that I knew roughly where it was (I obviously wasn't using Stellarium lol).

A 159x on my 130mm (f/6.9) Newtonian revealed the GRS and much more detail for a 0.8mm exit pupil and a 136x was even sharper for a 0.95 mm exit pupil (17mm & 20mm eyepieces combined with a 3x Barlow).

As Jupiter is not the easiest of targets to see clearly, the only corollary I can conclude from this is that the capability of being able to see the GRS is very much as dependent on aperture size and achieved exit pupil width as atmospheric conditions.

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With my 4" refractor, I find about 130x. With the C8, about 180x. To much magnification  , & Jupiter , just gets blurry.

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i can make out the GRS with my 76mm refractor typically using 80X - 96X  (0.95mm - 0.7mm exit pupil)l. I am more accustomed to planetary observing with a 200mm scope, which helps to determine familiarity at visually resolving features when using a smaller scope. 

 

 

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To the OP, a 2x Barlow I ordered arrived yesterday.  My 30mm lens on my 1250mm 10" dob with the Barlow installed gives me 83x magnification. 

Sure the planet was smallish but it was a beautiful view, sharp cloud bands, I could see all the moons. It was great. 

FWIW, I could still tell it was Jupiter with my 6mm in the Barlow at ~400x and it was bigger.  It was different though, fuzzy, had to keep chasing it.  Felt like I could see air waves from passing cars lol.

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1 hour ago, MarkVIIIMarc said:

To the OP, a 2x Barlow I ordered arrived yesterday.  My 30mm lens on my 1250mm 10" dob with the Barlow installed gives me 83x magnification. 

Sure the planet was smallish but it was a beautiful view, sharp cloud bands, I could see all the moons. It was great.

I agree, I saw Jupiter yesterday and it was astonishing at 80x, somewhat that magnification is great and the view is so clean (; Complementary to more magnification but mandatory also (to my taste).

 

 

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Using my ED80 for Jupiter, best mag to see detail is x150 - but I have gone higher!

Chris

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I think it is all down to seeing. Having more high powers helps find out what is the best view for you. 

As said above, I also agree that Jupiter is a bit more difficult than the Moon, Saturn or Mars on magnification.

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On 21/04/2016 at 00:34, AlphaOrionis said:

My telescope is struggling pushing 180x magnification, I make out the details but they are blurry. At 90x my image is very clear and sharp, but I can't make out the red spot. The telescope appears to have a limit of about 160x.

I'm about to buy a new eyepiece, and the best deal I can get right now is for a 128x. Will this be enough to make out details/red spot/moon shadows? Or should I try and find the ideal eyepiece that could push 150-160x to be safe?

Thanks!

Extra info:
ED80 80mm f/7.5 with a 6.7mm Explore Scientific and a 2x Televue Barlow (this gives me 90x and 180x)
Im looking at the ES 4.7, which would give me 128x

With the ED80, I would expect you to be using 180x on Jupiter only very rarely and on the best nights.  Most of the time the maximum best power would be in the 130-160 range - again depending on seeing conditions.  If you have to use a barlow make sure it is high quality - I prefer not using one unless absolutely necessary and good quality, a poor one would be more of a hindrance than a help to tease out fine Jupiter details. You have a Televue so should be OK.  Another good rule of thumb is to keep increasing the power until you cannot see any more detail then go back to previous (lower) power.  Time to get a couple more EP's if you've only got one or maybe two, 90x is a little too low for planetary and 180x is a bit too high for 80mm. Once the power is set, also remember to be patient (most details don't pop out immediately) and learn to record what you see, this helps you become a better observer and see more detail over time.

Edited by t0nedude

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Hiya,

My scope is similar to yours (Esprit 80mm) and the eyepiece that gives the best views of Jupiter that I have experienced is the Pentax XW 3.5mm. If your timing is right to catch the GRS and seeing allows it is easily visible :icon_cyclops:

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