Jupiter woes.

[nephilim]

Hi all, I'm new to all this & bought my first scope only a month or so ago (Skywatcher 130m EQ2), i've only managed 2 observing nights thanks to terrible weather.

My question is this- I used my first un-supplied eyepiece 3nights ago (Meade 5000 HD-60 9mm) I homed in on Jupiter and it was amazing, the contrast was great & the image sharp with 2 VERY distinct cloud bands visible. The problem was when I put in my 2x Barlow, although the bands were visible (faintly) the whole image itself seemed quite 'blurry' and wouldnt snap into focus properly , I do understand the limitations with my scope but I'd have thought that at the 200x the Barlow & 9mm would produce would be easily attained as the 'recommended' mag is 260x for a 5.1" mirror. Also I noticed that the scope itself was covered in a thin film of ice when i brought it inside ( I'd cooled the scope sufficiently b4 using it) I'm wondering if that would affect the mirror, maybe my 'untrained eye' needs a bit more practice or the scope really is pushed to its limits with 200x.

Thanks for reading.

[JamesF]

It's entirely possible that the sky conditions just weren't good enough to support that kind of magnification at the time you tried. There is a huge variation in the quality of the atmosphere from night to night and it's far from obvious when it's going to be at its best. When the seeing is poor quite often a barlow will just make things worse.

There are a few other things you could check though. It's not uncommon for dew to form on either the primary or secondary mirrors. A dew shield should help with that. You can buy them, or make your own out of camping mat.

If you had great views recently then it's unlikely that the collimation is very far out unless the scope has been knocked, but it's sensible to check collimation every so often. Some people use a laser for that whilst others use a Cheshire eyepiece. It's largely down to preference I think.

James

[DirkSteele]

As well as the suggestions offered up by James, I would ask what Barlow you used? Often the lower quality examples supplied as standard equipment with a scope are not great, and this may have contributed to the degraded image.

[JamesF]

That's a good point. The Skywatcher 2x barlows seem to be hideously variable in quality. Mine was awful. Don't bin it if you replace it though. They make create extensions for imaging if you remove the lenses

James

[breezy]

think my skywatcher barlow was one of the slightly naff ones cos its a marked improvement using my tal

[fredster]

I've been out twice this week looking at Jupiter and i experienced the same thing on both occasions, that was a break down in image quality above 150x. Up to 150x the view was sharp and detailed. Above 150x it was mushy and lacking. For me it was purely down to the conditions. Wouldn't mind betting, as James said, it was just down to the skies being poor.

Could be the barlow but don't bin it just yet. Give it a few more chances before you condemn it to the bin.

[nephilim]

Thanks for the advice!! I had wondered about the Barlows quality as it was the one supplied with the scope (Along with Skywatcher 25mm & 10mm, the 25mm is fine but as a glasses wearer i found the eye relief on the 10mm akward hence buying the Meade 5000 9mm which is far better) I just assumed barlows would be more or less the same ( obviously not haha) I'll use the Barlow for a few more sessions & if the results are similar then I'll invest in a better one. Any recommendations would be greatfully recieved. Thanks again .@James, a colminator sounds like a wise (and nessesary) purchase!

[fredster]

The Revelation 2.5x Apo barlow is a half decent barlow for the money (under £40). In fact its only really between that and the much loved Tal 2x (which is nigh on impossible to source now) for a budget barlow. Above that prices rise steeply to the Orion Short Plus, Celestron Ultima and Televue 2x barlow.

[username]

One thing to remember when trying to view jupiter is that it doesn't take magnification too well.

The detail on Jupiter is low contrast, faint brick coloured bands on a cream background, the structure in the bands have got quite subtle colour differences too.

When you increase magnification jupiter becomes dimmer in the eyepiece which will make it harder to make out all the faint contrast.

My best views of jupiter have been at x100 to x130 magnification. Try and resist the temptation to go to high magnification and keep the magnification to 1 X or 1.25 X your aperture in millimetres. The image will be smaller but much sharper plus if you keep looking you will start to see surprising detail.

[FarSide]

It's not anything to do with the quality of the barlow, i don't think. Jupiter generally isn't very appreciative of high magnification anyway especially at long focal lengths. At long focal lengths seeing conditions become far more pronounced and obvious making the quality of the view degrade.

Edit: Username had it before me. lol

[JamesF]

Perhaps it's at long focal lengths or with smaller apertures that magnification of Jupiter doesn't perform well visually. I had some stunning views of Jupiter at 240x with lots of detail to be seen, but that was in my 10" f/4.7 dob.

James

[username]

Perhaps it's at long focal lengths or with smaller apertures that magnification of Jupiter doesn't perform well visually. I had some stunning views of Jupiter at 240x with lots of detail to be seen, but that was in my 10" f/4.7 dob.

James

Yep you're right, 240x in a 250mm scope isn't pushing it too far.

I don't want to go in to exit pupil and everything in the starting out section but keeping the magnification approximately equal to the aperture of your scope in millimetres makes sure jupiter is bright enough for you to resolve the low contrast detail

[nephilim]

I'll give it another go with the Barlow wen the seeing is better but if there's no change i'll stick with the smaller view as even with a 9mm I was very happy with what I saw and as 'username' from Sweden wrote the more I study it the more I'll see, thanks again everyone (Very helpful).

[fredster]

I'll give it another go with the Barlow wen the seeing is better but if there's no change i'll stick with the smaller view as even with a 9mm I was very happy with what I saw and as 'username' from Sweden wrote the more I study it the more I'll see, thanks again everyone (Very helpful).

Sounds a great plan

[username]

I'll give it another go with the Barlow wen the seeing is better but if there's no change i'll stick with the smaller view as even with a 9mm I was very happy with what I saw and as 'username' from Sweden wrote the more I study it the more I'll see, thanks again everyone (Very helpful).

Patience at the eyepiece is the key to getting the most out of observing planets. With the atmosphere bubbling away above us distorting the image we have to wait for the moments when the best image is available. Also, as the detail on Jupiter is hard to see you need to practice seeing it. It's like anything, practice makes perfect.

When I first got my scope I was a bit unimpressed; compared to my old 60mm tasco I thought it wasn't much of improvement. I could see the bands in my old rubbish scope and the same in my new scope. It was only when I started forcing myself to keep my eye to the eyepiece that I started seeing much more.

Another thing you might try depending on your type of barlow. On your barlow lens can you unscrew the lens assembly from the bottom of the silver tube? If you can then you can screw this bit in to the bottom of the 9mm eyepiece like a filter. The the barlow lens acts like an ~1.5x barlow and now 2x. Your 9mm gives you 100x at the moment and this will put it up to around 150x. The image won't be as bad as it is at 200x.

Still make sure you give the lower magnifications a chance.

[username]

Sorry, I can't edit.

The the barlow lens acts like an ~1.5x barlow and now 2x.

should be

'The barlow lens acts like an ~1.5x barlow and NOT 2x.'

[Astro Imp]

All the above is relevant to the OP but also consider that at the moment Jupiter is still quite low in the Eastern sky which means you are looking through a lot of our atmosphere. Later when it is higher you are looking though less.

[nephilim]

Thanks 'username' I'll try putting the lense in the ep.

[Moonshane]

as well as all the other good advice, another reason to observe Jupiter a bit higher is that heat plumes from central heating etc destroy the seeing locally and this is more likely when the planet is lower in the sky.

[E621Keith]

If you are using over 200x magnification, seeing will become the main limitation.

I'm usually limited to under 200x magnification in my home in Southampton, but can often push over 250x in my parent's home in Middlesex. The local geography and how that affects airflow in my area probably contribute to this.

Your telescope can probably achieve near it's theoretical magnification limit in the still air in a remote desert mountain top, but not under the turbulent sky in UK.

[LukeSkywatcher]

I agree with what has been said. The poor views were down to a combination of pushing the scope past what it can do and the atmospheric conditions.

[Johannes]

I was looking at Jupiter last night with my 10" f6.3 dob with a 12mm eyepeice at 133 x and it was very fuzzy. I could make out two bands . But when I was out two nights ago it was so good I saw five bands across Jupiter. You get good nights and bad nights so keep observing you will see detail with practice. John

[Blurred Image]

I've recently started using colour filters to improve the contrast of the cloud belts. Blue works a treat, but even a moon filter can help. Just an idea, it's really down to personal preference.

N.