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Crosshairs in Jupiter?!

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Hi folks

Now I'm sure this is a stupid question :iamwithstupid:but I can't fathom the answer! I took delivery of my new SW Explorer 150PL earlier today and after setting it up I marched outside for my first sight of Jupiter. Although I think I got it lined up in my scope I got very little detail (I think due to poor light conditions) but I could also see a crosshair with a black blob in the centre in the middle of the planet. It didn't matter if the planet was off centre in the eyepiece - the crosshair was still centred on the planet? Why was this? Was I seeing the planet at all or something else? I feel sure I shouldn't be seeing a crosshair at all.....should I?!!!

Enlightenment would be most welcome!


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Second what matti said, you're almost certainly not focussed. As you got the scope today you're presumably using the supplied 25mm and 10mm eyepieces, Jupiter will focus to a very small disc in the 25mm EP (too small and bright to see cloud bands, in my experience, but great for seeing the moons) but the 25mm with the barlow, or the 10mm on its own will give a more "Jupiter like" view! You'll have to re-focus when you change eyepiece or add a barlow.

Enjoy the scope, it's great fun :)

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I agree with Mattifor as well - what you are seeing is the shadow of the secondary mirror and it's support arms. That means that Juipter was a fair bit out of focus - that's why you saw very little (none I suspect) detail on the planet - even small (60mm) scopes will show the 2 main belts on the disk of Jupiter, when it's in focus.

Try racking the eyepiece slowly in and out to reach focus.


PS: Don't worry, this is a very common issue when you are starting out !.

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Just to add to what John said - when your racking the focus in and out, if the disk with crosshairs gets bigger and fainter, you're going the wrong way - as you near focus, the disk should get smaller and brighter - it's surprising how quickly you can shoot past the focus point and back out of focus again. You'll soon get the hang of it.

Good luck

John (another John)

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