Newbie question on Jupiter - possible collimation needed?

[Dazaroth]

I'm an absolute beginner with an 8" Revelation Dobsonian. Absolutely love it so far, stars look awesome, looked at the pleiades and the moon (unfiltered so far, but Santa brought a really cool set of filters, barlows and plossls).

My question however is that when I used a plossl to look at Jupiter, I could see the disc of Jupiter itself absolutely fine.... but it looked like the spider on the inside of the telescope? Weirdest looking thing ever and after being all excited was a little gutting!

Anyhoo could anyone please advise on this?

Thanks muchly

[knobby]

Sounds like it was possibly out of focus ... The 4 vanes that hold the secondary mirror do cause spikes on bright objects but shouldn't be so noticeable as to spoil viewing unless oit of focus .

Could you see any of Jupiters moons , if focused they will appear as tiny pin pricks ...

Also try racking focus in and out very slowly and let the scope settle in between moves

[ronin]

Being a reflector you will get 4 spikes, Jupiter is bright so the spikes will be very obvious.

You also may need to increase the magnification - you do not say  which plossl you tried/used.

Again Jupiter is bright and unless the magnification is reasonable then the image will be bright enough that the detail is swamped.

finally what time?
If too low then the atmosphere makes things indistinct.

[John]

If the "spider" had black legs and body against the bright disk of Jupiter then the scope was not in focus as knobby describes. If the "spider" legs were spikes of light then it's the effect that ronin describes.

[wheresthetorch?]

And if it moved, there was a spider in your scope...

[Dazaroth]

Was a 9mm plossl and was black legs against the disc. Thanks guys that's very helpful I shall give another try. And add a filter

[Dazaroth]

And thankfully not a real spider! What's the actual term for these things? Spider just kinda made sense

[wheresthetorch?]

Yes, it is often actually called the spider, or sometimes the 'vanes'.

[John]

Was a 9mm plossl and was black legs against the disc. Thanks guys that's very helpful I shall give another try. And add a filter

As you get closer to sharp focus the planets disk will get smaller and smaller and the shadow of the secondary and it's supporting vanes will disappear. Personally I don't bother with a filter for Jupiter even with my 12" scope.

[Dazaroth]

Problem solved! Thanks for the advice guys, damn good viewings last night