Magnification for Cassini Division

[M4lcs67]

Just so I know in my own mind what equates to magnification. Is it the aperture x the focal length of the scope? Where does the size of the eyepiece come in? With both fine tuning rings attached to my 10mm Hyperion it comes down to around 8.2 mm I think. Would I be advised to get a more powerful eyepiece than that? Obviously it is always seeing depended.

[rowan46]

magnification is focal length of the scope divided by the focal length of the eyepiece

[DanH]

Hi Maic,

Magnification is equal to focal length of the scope divided by the focal length of the eyepiece used.

For example : A 960mm scope (focal length) with an eyepiece of 12mm will provide you with a magnification of 960/12 = 80

[DanH]

Sorry for the triple answer...

[michael.h.f.wilkinson]

Sorry for the triple answer...

Sorted

[M4lcs67]

Thanks loads, fellas.

So apeture doesn't come into it? I was confusing myself I think.

[Qualia]

So apeture doesn't come into it? I was confusing myself I think.

The Cassini Division is a weird one in my experience and I'd suggest you check out your local seeing conditions and one night when the conditions are very good, head out about 12.30am with a decently cooled telescope (frac or newt) with the mission to do nothing else but view Saturn. Just sit with him and keep your eyes peeled. And if you're not successful the first night, go out 4 minutes earlier and just keep coming back, time and time again.

In my experience, it isn't something I can observe all the time and generally, I have more luck finding really faint fuzzies, or clearly making out six, brightish Saturnean Moons than ever seeing the Cassini Division. I honestly don't know why this is, but when you see it you'll know. It is not like you have to do averted vision or anything. It's like a 4b, reasonably thick pencil line drawn around the ring.

Although aperture isn't necessarily important, it really does help for it just makes the object brighter and so makes seeing things easier. Nevertheless, I've found that with both the 4" and 10", I never really need to be over-stepping 140x to 170x.

Just keep at it. The CD is one of those weird ones and perhaps adds to that frustrating mystery of Saturn.

[John]

The Cassini Division is a bit easier to see with my 4.7" refractor than it is with my 4" and much easier with my 12" dobsonian. Steady seeing conditions make a lot of difference though as, perhaps to a lesser extent, do eyepieces that minimise light scatter around bright objects.

[knobby]

I think that the common mistake is to try too much magnification... Saturn is much sharper at lower mags but we all want to see it bigger I do it myself, but as has been said the seeing isn't too great at the moment.

try to accept that ' it is small' and unless you have a huge aperture / focal length scope on a night of good seeing... That's it... Its small... Its raving miles away

but seriously if you want to see casini, then start at a lower mag, maybe 100 x and just concentrate on getting the best focus you can. Then, just stare... And stare... It will pop out in a moment of good seeing

Once you've seen it then try upping the mag a bit and try again.

Keep at it and good luck.

Oh, did I mention make sure your well collimated and cooled if its a reflector

[M4lcs67]

Thanks for the additional advice and tips. It really must be the holy grail and It will be just a case of trial and error then? And also a sensible magnification that allows it to come into focus. I have been guilty of throwing a shed load of magnification at certain things in the past, but all it gives you is a blurred image. I have learnt that in order to get a nice clear image you do need to reign in the mag.

[spurius]

I cant see it in my scope. I have a 8inch reflector although its essentially less than that due to the secondary mirror blockin some light. I used both a 4mm and 6 mm eye pieces and my scope is 1200mm focal length. I have absolutely no idea what the actual magnifications are but I couldnt see any gap in the rings. What size eye piece would I need to see the cassini division assuming all else is good? Smaller eye pieces seem to have higher magnification but lower resolution so I dont know how small I can go. Saturn is at its best about now afaik.

[spurius]

Also I can see 2 small dots next to saturn. Im assuming the brighter one is titan, whats the next brightest of saturns moons and how much smaller is the cassini division?

[Moonshane]

if Titan is a pea then the Cassini division is a thin pencil line. it's easily seen in my scopes (from 6" - 16") from about 100x. you need to await moments of good seeing, have your scope cooled and collimated and look in the right place. a lot of people think it's near the middle of the rings but in the eyepiece it looks almost 2/3rds of the way out.

[John]

This is quite a good illustration of the principle features of Saturn and it's ring system:

[Moonshane]

nice one John I fear they are imagining Encke's Division!

[Donkeiller]

Saw Cassini at x77 last night. But much better at X120. Less good at x150.

[mdstuart]

On another post someone pointed out the earths moon would fit through the Cassini division!

mark

[moffer]

Not difficult at x150 a few nights ago despite mediocre seeing. Cassini Div was a lot more difficult and not seen with certainty..

[moffer]

Oops...wrong thread!