Planetary Focusing Help

[IAmMummRa]

Hi all!

My kids and I are new to astronomy and we have purchased a Celestron Astromaster 130 (http://www.celestron.com/astronomy/celestron-astromaster-130eq.html) in hopes of observing planets mostly. We've had pretty good success looking at the moon, nice and sharp w/ pretty decent magnification using the 10mm eyepiece (able to see mountain ranges around the edges, cool). So far so good, let's try Saturn, it's visible in the sky these days.. Womp womp. The best we can get at a reasonable level of sharpness is barely enough to see the rings sticking out around the side of the planet and still painfully small in the viewer (my 8 year old swears she cant see the rings). Attempts to zoom in are instantly met by extreme blurriness and eventually the appearance of cross hairs (from one of the mirrors?) in the center of the planet. I have the collimation accessory and i've used it a bunch of times in hopes that i've simply not aligned everything properly, but these are met w/ the same result, beautiful moon, disappointing everything else. So at this point i'm wonder if it's maybe the stock eyepieces are just Rubbish? or are they too low of magnification and should i buy a 5mm eyepiece? or are the mirrors not aligned properly yet? I've kinda gone as far as i can on my own here, definitely in need of some advice.

Thanks so much!

[nightfisher]

It wont hurt to do a collimation check again, and it could well be worth trying a better eyepiece, a good one to get would be the 8mm BST starguider from skies the limit @ £47 do you have an astro club near you that you could take your scope to and maybe try some other eyepieces in it

[David Smith]

The problem with Saturn at the moment is it's low altitude. This means it is never high enough to get a clean view which in turn allows the magnification to be ramped up. A new eyepiece as nightfisher suggests may well be a good move as the supplied 10mm eyepiece is not the best which won't help.

[Russe]

This scope's ability to magnify tiny planets is not the greatest with a focal length of 650mm.

The 8mm BST is great though. But if your collimation is good then I'm afraid the planets low altitude might make it difficult. Jupiter will be a much more rewarding subject later on in the year.

And, if Celestron's Barlow lense is as Rubbish as skywatcher's, then that would be an option too.

[AndyWB]

I was looking at Saturn using a 5mm BST in my Skywatcher 130p (which has a similar 650mm focal length, so a very similar spec scope) two nights ago, and had something of the same; it felt like I couldn't get it in focus at all. It was still recognisably Saturn, though. I think this was due to it still being twilight, and it's low in the sky. I ended up using the 8mm, which gave a smaller, sharper image. It was about the size of a pea, I'd guess, and still a little blurry - you're never going to get images like Cassini!

I would expect you to be able to see the rings though. I can see them at quite a low magnification.

When you say "zoom" what do you mean? Taking out an eyepiece and putting in another?

Oh, and the crosshairs are the shadows of the supports for the secondary mirror. If you see those, you're WAY out of focus.

[Pappy Nick]

@ IAmMumRa - I too think you may be confused about the focus knob's function - it does move in and out but, as far as I'm aware, it doesn't zoom. Zooming tends to mean increasing/decreasing the magnification and is usually done with a Zoom Eyepiece. As AndyWB says, if you can see "crosshairs" then it sounds like you're out of focus.

When Saturn's higher in the sky and it's a nice, clear, dark, cold, crisp winter's night you'll be surprised at the difference in what you can see through your 'scope.

[IAmMummRa]

Wow, thanks everyone for your insight.

By zoom, i apparently meant focus, sorry, newb here

I'll also try the 8mm eyepiece suggested.

Thanks so much!

[AndyWB]

... it does move in and out but, as far as I'm aware, it doesn't zoom.

Unless it has a built-in barlow lens - in which case, it could have a 'zoom'. But it didn't mention that on the spec for the scope.

I'd try and borrow an eyepiece rather than rush out and buy one; I'm not sure that's the issue.

[IAmMummRa]

Much better results this evening.. completely reset my scope in the tripod, culminated once again and found a good comfortable height to view / focus at. Extremely sharp view of Saturn w/ very obvious separation between the planet and the rings with both 10mm and 20mm eyepieces.. very cool stuff. Still rather small in the viewfinder but i'll take it!

[AndyWB]

That's more like what I'd expect! Could be collimation or conditions.

Yes, it is small. A higher power eyepiece like the 8mm would increase it's size, and a 5mm even more, but even then its still small. And I've not had much luck with the 5mm in the last month if so (it's blurry), so I've been using the 8mm. It feels right.

But it's probably always going to be small!

[gbeecham]

Good to know that you get see the rings with the Skywatcher 130p!! If the cloud ever clears in Essex I will be out like a shot! How much longer have we got before Saturn goes away for a while?

[AndyWB]

Good to know that you get see the rings with the Skywatcher 130p!! If the cloud ever clears in Essex I will be out like a shot! How much longer have we got before Saturn goes away for a while?

Conjunction is in November, and I guess how long it is depends on where you're viewing from and how much atmosphere you want to view through. For me, I'd guess a month or so, though I'm new at this myself.

Regarding the rings in a Heritage 130p - they're hard to miss when they're open wide! On a stable night I think I 'saw' the Cassini division too (I say 'saw' as, apparently, technically the scope is too small to resolve it - but your eye is good at interpolating, so you perceive it anyway, if that makes sense). I've also seen 4 of the moons on another night, with a shroud fitted around the open truss to improve contrast