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Attempting to Observe Jupiter/Venus

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12 years 4 months ago #92694 by Graham
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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12 years 4 months ago #92697 by conor-figgy
Replied by conor-figgy on topic Re: Attempting to Observe Jupiter/Venus
Ahh, awesome... thanks guys! Yeah that's pretty much what I can see when trying to view the planets, but not the moon for some reason... I'm from Kilkenny but got to college in Dublin.

So, collimation it is then.

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12 years 4 months ago #92698 by Calibos
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 :D

Keith D.

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12 years 4 months ago #92700 by conor-figgy
Replied by conor-figgy on topic Re: Attempting to Observe Jupiter/Venus
Yeah, I'm using the three eyepieces that come standard and the barlow was bought by the previous owner.

I'll try look into this correct image prism.

Actually, you might have something there... I don't think I actually used the 6mm and the barlow together as I thought it would be too much, whoops. Hmm, perhaps I was trying to view it with an underpowered eyepiece and therefore went way way past the focus point. Well, tonight shall hopefully tell! Cheers!

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12 years 4 months ago - 12 years 4 months ago #92708 by dave_lillis
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 ?

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Last edit: 12 years 4 months ago by dave_lillis.

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12 years 4 months ago #92722 by conor-figgy
Replied by conor-figgy on topic Re: Attempting to Observe Jupiter/Venus
Just back in, when I 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. So, other than when I observe the moon; I can see the spider vanes and mirror shadow, again like the image posted previously.

I don't have a laser collimator, neither do I know any other amateur astronomers around where I live. Should I just wait until I get a chance to bring it to someone knowledgeable or invest in a laser collimator and learn how to do it myself?

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