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Astro Adj

Ideas on how I can get more detail when viewing Jupiter?

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Having had my first good look at Jupiter I'm hooked and want to get back out there and see if I can see just a little more detail. I've managed to see the darkest bands (there are 2, one either side of the equator) but not much else.

I've been looking into how to improve the situation, but come across so many ideas and tips my brain is now beginning to run for cover in case I try to cram more knowledge in! I thought now would be a prudent time to ask for help!

Okay, so my scope is a 5" Newtonian Reflector with a 650mm focal length. I've got the following EPs: 25mm, 10mm, 6mm and a 2x Barlow. If my maths is right that will give 26x, 65x and 108x magnification, or 52x, 130x and 216x with the barlow. To date the best view I've had was actually using the 6mm, and not the 6mm in combination with the barlow.

I've also tried reducing the amount of light entering the scope by putting the dust cover on then taking off the small cap. However this didn't seem to improve things much.

So, I've come up with the following ideas, and wondered if someone could clarify if any of these would work - or indeed if there is anything else I can try!

1 / Go to a darker site. I wasn't sure about this as the brightness of Jupiter isn't the issue, so would travelling out to the sticks be worthwhile?

2 / Invest in a better EP. I've seen a 4mm EP that would give higher magnification, but would this necessarily improve the detail? I'm confused as I imagined by increasing the size of the object it would be easier to see more detail, but my experiments with the 6mm and barlow contradicted this! So if I do go down this route I'm not sure if getting a higher-power EP would be best, or a better quality 6mm? Or maybe a better quality barlow?

3 / Use some kind of filter. I found that I've actually got a Moon filter (I thought it was a cap for my 10mm EP until I realised I had a spare cap and it had 'Moon' written on it!) but haven't used it. In fact I can't seem to get it to fit on any of the EPs...am I doing something wrong? If the Moon filter is not effective on Jupiter, is there a better one to consider?

4 / Buy that 12" Auto Skyliner dob in August's Sky at Night magazine and grovel to my wife for the next few months...

Any and all ideas / explanations will be welcomed!

Thanks!

Adrian

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Hi Adrian,

Jupiter is quite low in the sky so you are looking through quite a lot of atmosphere which will affect seeing. There is a limit to how much magnification is possible before the image degrades - I guess you've already found that out by trying the 6mm with the barlow.

I have a 12" FlexTube and looked at Jupiter a few days ago. The eyepieces used were all Pentax XWs and the best view was with the 14mm (107x), although the 10mm (150x) was tolerable. So your 108x and my 107x are equivalent despite my bigger aperture and premium eyepieces.

Mike

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My suggestion would be simply to keep observing Jupiter. With practice you will find that you can pick out more details in the moments of good seeing. On a good night, with my 4" scope I can see quite a lot of details:

http://stargazerslounge.com/observing-planetary/85673-jupiter-quick-grab-go-session.html#post1272190

A few nights ago I viewed Jupiter with my 12" dobsonian and, while the features were a little easier to pick out, there was not a whole lot of improvement over the 4" refractor. I put this down to the fact that, with Jupiter being fairly low in the sky, we are looking though a lot of atmosphere, light pollution and heat from the ground ebbing away - these factors affect a larger aperture scope more than a smaller one.

When I was a lad (this was 35 years ago !) a mate and I borrowed a 60mm refractor and observed Jupiter from my bedroom window for many nights, drawing what we could see each night - I still have those drawings and I'm always suprised at the details we captured with such a smaller scope, especially towards the end of the period when our eyes had become "trained" in picking out the faint contrast details.

Nights of good seeing will help and a yellow filter can help improve the contrast a little as well bit, IMHO, it's time spent at the eyepiece that helps most though.

John

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Thanks for the reply Mike. That's interesting, and definitely tallies with what I noticed when observing. So it seems that, with current viewing conditions, 108x magnification is my best bet. That's one part of the puzzle solved!

Can I ask if you noticed a difference when you upgraded your eyepieces? Now that I know the magnification I should be using, getting a better barlow doesn't seem to make a lot of sense, but do you think a better eyepiece (I've been looking at the 6mm TMB planetary one) would help?

Thanks again for the help.

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My eyepieces were acquired when I retired. Within reason, cost was not an issue (no mortgage, bills or kids) so I could afford good eyepieces from the outset.

My initial purchase was this ... Eyepiece Sets - Meade Series 5000 Super Plossl Eyepiece Set but after a year or so I had the opportunity to borrow one of these Pentax - Pentax XW 5mm

The Meade eyepieces are excellent but no match for the Pentax. Looking through the Meade 5.5mm was like looking through a pinhole compared to the Pentax "porthole" - I now have a set of Pentax XWs :)

So, yes, upgrading your eyepieces does make a difference but more to do with eye relief, field of view, brightness etc rather than magnification.

If you are looking at planets. magnification is important to allow you to see more detail. If you are looking at DSOs the extra magnification is normally pointless - something small, faint and fuzzy becomes a bit bigger but fainter and fuzzier.

Don't dismiss barlows though. A decent one will not degrade the view and will allow you to spend your eyepiece budget on fewer but better quality eyepieces.

Mike

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I agree with what John has said. When I first looked at Jupiter through my 6" scope it was really low and all I saw was an orange blob. The more time I have spent viewing the more I see (obviously there is a limit). Last night I spent a couple of hours as the seeing was so good. During brief periods when the air was really steady I could see fine bands that I had not noticed before. The maximum magnification I used was about x200 (although I seem to be able to go much higher on Saturn). Good eyepieces/barlow do make a difference but time and patience is also important.

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As usual, I agree with John. You should know, however, that resolution increases directly with the size of the scope, so a 12" scope has 2.4 times the resolving power of a 5" scope. What this means is that the bigger the scope, the finer the detail you can see. Also, the quality of your eyepieces affects your view to some extent. To this date, the best view of Jupiter I have ever had was through a 6" f.8 Newt with a Pentax eyepiece.

I was out looking at Jupiter last night, through my 105mm refractor, and could see the equatorial bands most of the time, and occasionally for tenths of a second I could see all the bands and zones. I was using the refractor because it is said to get better contrast than the Newtonian, and also because it looks way cool.

It is a matter of spending the time to look at your target until you begin to see things you haven't seen before.

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Thanks again for the replies everyone.

I have decided to stick with exactly what I've got for now. I want to find the limits of my equipment before I start making any changes so I'll be able to appreciate any upgrades.

It sounds to me that the weakest link in my observational chain is, well, me! I'll continue observing to get more experience and report back if I manage to eek out any more details. I'm thinking about sketching, but my drawings are awful...maybe I need more practice there too!

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Remember to make sure your scope is well collimated and that it's had time to cool down (with the cap off) to the ambient temperature. A hour should do it for your scope.

It's my understanding that the amount of fine detail visible on bright extended objects such the Moon and larger planets will be heavily influenced by the presence (or not) of high frequency fluctuations in the atmosphere. These are generated by the presence of the jetstream at around 30,000 feet. On nights when the jetstream is overhead you will be very unlikely to see fine detail, however little the low frequency fluctuations in the atmosphere are. Low frequency fluctuations are mainly caused by winds (very low frequency), thermals (lowish frequency) and terrestrial heat sources such as roofs, boiler exhausts etc. These make a image appear to dance about, wobble or distort. High frequency stuff makes the image look indistinct and blurred. Most nights in the UK have a bit (or more!) of both.

You can get a jetstream forecast at:

Metcheck.com - Atlantic Jet Stream Forecast - [updated on 22 August 2009 at 21:00] - Weather Feeds - Live Data - Long Range Weather Forecasts

Note that the forecast is for midnight, therefore for a forecast for say a Wednesday night you need to look at Thursday's forecast. Next week's forecast is pretty appalling with the jetstream almost exactly overhead in the UK. (sigh)

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I'm thinking about sketching, but my drawings are awful...maybe I need more practice there too!

This is a great idea Adrian !.

Setting aside the quality of the results, the process of sketching requires careful observing so it will help you percieve more details.

John

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Just some comments on the above:

- A darker site may help - not because of the brightness issue, but because there is less air pollution out in the sticks, and less turbulent air from people's rooftops etc.

- As a general rule, you won't see any more detail using an eyepiece shorter in mm than the focal ratio of your scope. So for an F5 scope, a 5mm eyepiece shows you the most detail. Smaller eyepieces will show a "larger" image, but there won't be any more information revealed in it.

- The "standard" SkyWatcher barlow is just a single uncoated lump of glass, and so it is not very good. I do not know how much better (if at all) the "deluxe" barlow is, that comes with some SW scopes.

- The moon filter should screw on to the bottom of the eyepieces if it is a standard size

- A blue filter will help you see more of Jupiter

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Hi Adrian, I agree with you that sketching is a very good Idea....I'm useless at art but I've started sketching and i think its improving my observational skills no end.....when sketching something you have to actually ask yourself whats there,, rather than letting the view wash over you...if that makes sense.

The other night ( and just about every night I'm observing the planets )I fiddle and tinker with various combos of ep's and my one planetary filter and barlows ....some nights my 7mm gives me the best views, other times it's my 26mm barlowed.....I guess what i'm trying to say, is that each night is different.some nights you can boost the mag quite high and still see detail other nights ya' have to back off and use less mag to see the detail.

The other night I looked at jupiter for hours and In that time there were periods of fantastic seeing and the next it was carp...I tend to pick out more detail with both my eyes open,but looking with one eye into the ep ( I can't do this on DSO's as they aren't bright enough) .It's taken a little practice but seems to work well for me on the planets........ keep at it and you'll rewarded for your troubles...:o

regards craig :)

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Hi Adrian, I agree with you that sketching is a very good Idea....I'm useless at art but I've started sketching and i think its improving my observational skills no end.....when sketching something you have to actually ask yourself whats there,, rather than letting the view wash over you...if that makes sense.

The other night ( and just about every night I'm observing the planets )I fiddle and tinker with various combos of ep's and my one planetary filter and barlows ....some nights my 7mm gives me the best views, other times it's my 26mm barlowed.....I guess what i'm trying to say, is that each night is different.some nights you can boost the mag quite high and still see detail other nights ya' have to back off and use less mag to see the detail.

The other night I looked at jupiter for hours and In that time there were periods of fantastic seeing and the next it was carp...I tend to pick out more detail with both my eyes open,but looking with one eye into the ep ( I can't do this on DSO's as they aren't bright enough) .It's taken a little practice but seems to work well for me on the planets........ keep at it and you'll rewarded for your troubles...:)

regards craig :D

yes i totally agree with keeping both eyes open i have found this definatly works for me :o

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Thanks again for the advice, everyone.

@ Michael - very interesting, thanks for the link. I've added it to my list of weather sites and will check it regularly.

@ John - I can see what you mean, when I sketch I seem to interrogate the image more than when I just look at it. In doing so I've already noticed some additional detail!

@ Vulpecula - Thanks for the tips. I really should travel out to a dark site more, I'm fortunate in that there are some really good ones near me. However my wife won't allow me to go alone, and sometimes it's hard to find a friend to accompany me on a bit of spontaneous star gazing!

Very interesting point regarding the EP size and detail. That would explain why using the 6mm with a 2x Barlow doesn't resolve any more detail - the equivalent EP would be 3mm. However if I combine the 10mm with the Barlow... Speaking of Barlows, I'll be buying a Tal 2 x soon as I don't think the SW one is up to much really.

Thanks also for the tip on the moon filter. I've been holding up to me eye, then peering through the EP! I should have checked the bottom of the EP but it never occurred to me!

@ Craig - I know exactly what you mean, I was sketching the other night and picked up some detail on the south side of Jupiter that I'd never seen before. And actually, the finished sketches aren't THAT bad. Too bad I can't draw a good circle, though.

Seeing plays a huge part, doesn't it? As I understand it if the seeing is bad, when you switch up EPs you are magnifying not only your target but also the atmosphere, which exacerbates any atmospheric nasties such as the issues Michael mentioned above. On nights like that you're definitely right about keeping the magnification low!

Interesting tip about keeping both eyes open. My current technique is to open both eyes but cover the left one - I find constantly squinting is actuall quite painful so resorted to this. I look like a goon but thankfully it's always dark when I do it! I've also got a headband / flannel combination that I use in extreme cases, but this one really marks me out as a buffoon. Comfy, though.

@ Dazraz - thanks for confirming - I'll be sure to give this a go!

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