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Jupiter watching and a suprise


demonicrage
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hi guys, i was looking at jupiter tonight but i think my telescope isnt up to the task.

i got it up with 6.5 plossi and 2x barlow and the focus was bad but this was the best i could get as it went blurry either way i turned the focuser. after taking out the barlow i stood and looked at it with just the 6.5mm, around 20:15 i saw what i can only describe as a metorite passing just above it, just as bright as jupiters moon to the right of jupiter itself.

i hope someone else saw this tonight or im seeing things. also i need some advice about upgrading my telescope

Thanks

Kris

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What kind of scope do you have? A 6.5mm EP with a barlow would be too much mag for many scopes, and possibly too much for the seeing quality. And maybe too much for Jupiter - I've read that Jupiter does not take higher magnification very well. If the focal length of your scope is over 650mm, then you would be using over 200x magnification, which is not doable under all circumstances. I mostly use 150x on Jupiter.

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I think you could try the 25mm eyepiece with the barlow. That would give you 112x magnification - if you can't get a sharp (admittedly not very large) image at that magnification, then you need to consider what parts of the optics are preventing this. The eyepieces could be poor quality, the barlow is I think likely to be poor quality, and the scope itself might be struggling. For example, the scope might need collimation - something I have no experience of, but apparently this is quite hard to do with a Seben because of their particular design.

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One thing to be aware of with Jupiter is it has a lot of limb darkening - the thick atmosphere causes the edges of the planet to look much darker than the middle, so it is hard to find the right focus point, in comparison to saturn where the rings can look like they are cut out with a razor. To focus on Jupiter, I actually bring the moons to sharp focus and then look at the planet knowing it is in focus.

Edited by Ags
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Your scope has a focal length of 1400mm so the 6.5mm plossl with the 2x barlow lens will be giving 430x - this is far too much power for the sort of viewing conditions we get in the UK, regardless of the scope used. As has been said you will do much better with Jupter by using 100x - 150x which equates to eyepieces in the 15mm - 9mm range. The zoom might help if it's a good quality one but not if it's low quality I fear. Personally I'd get a decent quality 10mm eyepiece and stick to that for Jupiter with your scope.

PS: Unless you have already bought it, I would not recommend a Seben zoom lens.

Edited by John
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hi cheers for the info, it not a seben zoom lens, my mother is buying it for for a belated birthday present. ill see how it goes but will take your advice and get a 10mm too.

Thanks

If the zoom is good then you won't need the 10mm :)

The Hyperion zoom is great but it costs - depends how much your mum budgets for your birthday. I usually get socks etc from mine :)

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If I remember rightly (my father-in-law once had the 6" Seben) your scope has a short focal length spherical mirror coupled with a barlow built into the focuser tube (to give it the longer focal length and as an attempt to lessen the severity of the spherical aberration of the mirror). With this set up it will be difficult to obtain good images at high magnifications on anything but the moon (even when accurately collimated - which is difficult with the built in barlow). I certainly wouldn't attempt to use another barlow on it.

I think you will find you get the most enjoyable images by keeping the magnification down and hunting down targets like clusters and the brighter planetary nebulae and galaxies.

When Saturn comes back round you might also find it a more pleasing target.

When you say upgrading do you mean improving it or replacing it?

Edited by haitch
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i was meaning improving the secondary mirror and the focuser.

cheers haitch

The Seben uses spherical primary mirror and a corrector lens at the bottom of the eyepiece drawtube to produce the 1400mm focal length in a relatively compact tube. At the budget end of the market this is not a great optical system unfortunately. I doubt you could find replacement mirrors to suit the scope as it's a specialised design.

A replacement focusser would cost around £80.

Personally I think you would be best to use the Seben for low power viewing, as haich suggests, and getting used to using a scope while you put some £'s together for your next one.

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Things whizzing past my field of view isn't uncommon for me either. On only about my 3rd or 4th session ever, I saw a plane fly right across the Moon as I was viewing it through a 10mm. A few other times I've had shooting stars as well which are always a cool surprise.

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  • 2 weeks later...

There's so much space junk up there that it seems more common to see stray objects than not.

As well as ditching the additional Barlow, ditch the erecting piece, you don't need things the 'right way up', you need things a clear as possible and any unwanted glass is going to add abberation.

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A couple more things to mention..

1/ make sure you give your scope time to cool. A minimum of 30 mins and preferably an hour is good. This makes a good difference.

2/ The later the better. By midnight the sky should be a bit more settled and clear. Also be aware that below 30deg Alt the atmosphere will upset the view a lot.

3/ Try a filter. I find an 82a (light blue) filter works well with Jupiter without cutting too much light.

As has been said, in your scope a 10mm will give you the most detail under UK skies. 150x ish is best.

Better luck next time :)

Edited by Revs
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