Attempting to Observe Jupiter/Venus was created by conor-figgy

Hey guys! I'm a relatively new amateur astronomer and tonight I tried to view Jupiter and Venus through my Celestron AstroMaster 130EQ. So, when I managed to get it in my scope this is what I saw:

Apologies for the crude ms paint drawing. The grey is the planet and the black is the structure of the mirror holder (as far as I can see). So, my questions are:

1) Why can I see the struts of the holder? I've observed the moon many times and it's never been in the way.
2) I couldn't get either planet into any recognisable focus, and ideas to why?

Thanks!

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Replied by dave_lillis on topic Re: Attempting to Observe Jupiter/Venus

have you tried focusing on the moon and then moving the scope to jupiter without changing focus,
On bigger dobs, you do get the vains holding up th secondary as spikes on the brightest stars.

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go.
+ 12"LX200, MK67, Meade2045, 4"refractor

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Replied by dave_lillis on topic Re: Attempting to Observe Jupiter/Venus

I have to say, Im having trouble interpreting your image, do you mean you see a circular disk with zero details and 4 lines or are you seeing a fuzzy jupiter with almost no detail and 4 lines ?
If the bright illumination/planet image in the center perfectly center or is it oblong/lobsided.

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go.
+ 12"LX200, MK67, Meade2045, 4"refractor

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Replied by dave_lillis on topic Re: Attempting to Observe Jupiter/Venus

yea, definitely sounds like it's out of focus, maybe there is a loose mirror somewhere and it's shifting when you move the scope, you need someone experienced to look at it for you.

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go.
+ 12"LX200, MK67, Meade2045, 4"refractor

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Replied by Graham on topic Re: Attempting to Observe Jupiter/Venus

Sounds like colimination

In a misaligned scope, the star is out of focus and will appear as a doughnut shape with a dark center. If your telescope is misaligned, this dark patch will be perfectly centralised within the bright ring. This is actually the shadow cast by the secondary mirror, and you may also see the spider veins (as in the figure below). When the optics are in need of alignment the dark patch will be off center.

Source

If it is collimated then perhaps it is collimated with mirror travelling too far up the tube?

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Replied by Calibos on topic Re: Attempting to Observe Jupiter/Venus

Not so fast. Its unlikely anything to do with collimation. If you are seeing anything like your diagram or that photo you are looking at a grossly out of focus image.

Are you using the eyepieces that came with the scope?

I read that the scope has some kind of correct image prism thingie for Terrestrial viewing. Can this be removed? It might be preventing you reaching focus for celestial objects.

You do realise that even with a barlowed 7mm giving you about 150x that Jupiter in the eyepiece wont look much bigger than the full moon looks to your naked eye when you look up at it. ie. Are you sure you aren't bypassing perfect focus when the image of Jupiter is at its smallest and sharpest because you are saying to yourself, "Nah, shouldn't be that small!" 'Fraid it is mate

Keith D.

16" Meade Lightbridge Truss Dobsonian with Servocat Tracking/GOTO
Ethos 3.7sx,6,8,10,13,17,21mm
Nagler 31mm

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Replied by dave_lillis on topic Re: Attempting to Observe Jupiter/Venus

Your sharpest image will always be with the longest mm eyepiece, leave the barlows out, it's also the lowest power, so the smallest image. If that doesnt work for you, then the higher power eyepieces are only going to be worse, presuming they all reach focus.
If you are seeing exactly the image from 4 posts ago, then your eyepiece is not focused, maybe your primary mirror is too far down the tube ?.
if it is what you're seeing then your moon images must be out of focus aswell and look mushy/blurry/soft.

In that image from 4 posts ago, it is slightly out of collimation, but you still be able to see some sort of image when focused. What do they brightest stars look like through the lowest power eyepiece when focused , are they dougnnuts?, flaired with a fan like comet tail, or like boiling dots/points ?

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go.
+ 12"LX200, MK67, Meade2045, 4"refractor

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Replied by dave_lillis on topic Re: Attempting to Observe Jupiter/Venus

conor-figgy wrote:

tried to observe a star it looked like the image posted earlier and the boiling dots/points as I focused "out" if you know what I mean.

hmm, interesting, so when you get the boiling point for the star, thats the focus position and that'll be the focus position for every object in the sky with that eyepiece obviously. i'm kinda wondering are you thinking that the scope is focused when the focuser tube is fully racked in, by what youre saying.
The boiling is normal unfortunately, the atmosphere and thermals in the scope causes it.
IF you are seeing stars like that, then there is nothing wrong. Spider vains are normal on the brighter stars when focused, nothing you can do about it. If you view of Jupiter is very small, you could get spider vains there aswell.
If you move the scope to Jupiter and all you see is a fuzzy disk without changing focus or eyepeice, then I'm left wondering is this a "unrealistic expectation" thing going on here,

Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go.
+ 12"LX200, MK67, Meade2045, 4"refractor

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