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Saturn

justin138

By justin138
in Observing - Planetary

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justin138

justin138

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Morning folks,

Set the alarm for 4am to see the ringed planet and wasn't disappointed! Best I've ever seen it, lovely shadow of the rings on the planet and looks like a big diamond in the sky, fantastic!

Using my 10" F5 Revelation with a X2 Barlow and a 12.5mm eyepiece, I only caught what I think was a fleeting glimpse of the Cassini division. Now I would have thought it would be more prominent than it was.

Question is: what do I need to see the division clearly, more magnification? Filters? New scope with different F number? :rolleyes: The seeing was a bit iffy with some boiling but there were moments of remarkable clarity.

Be interested on your thoughts on this as I must confess to being a tad disappointed with no Cassini division but still well pleased with the general view of this lovely planet!

Cheers

Justin

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justin138

justin138

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No Cassini with the dob... :shock:

Tell me about it Kain, was expecting a simply PERFECT Cassini but was no there! The shadow on the planet body was very clear so thought Cassini would be too. Ho hum!

Scope was collimated about a week ago and hasn't been whacked too much since then! I think I'll re-collimate anyway and try again tomorrow. Perhaps my laser collimator needs collimating.

i did wonder if I needed higher mag but with F5 dob, X2 Barlow and 12.5mm, was getting 203x which should be enough?

Guess there's always tomorrow...... :rolleyes:

Cheers

Justin

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justin138

justin138

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You can see the cassini division in a 4" scope or even smaller

Read this article:

http://www.cloudynights.com/item.php?item_id=1132

Although the rings are closing up at the moment

Excellent article Gordon, bit heavy for this early hour though! I shall re-collimate today and try again tomorrow morning. Saturn was very bright, wonder if this might have some bearing on it or am I missing the point somewhere?

I will also try the Smellyscope as well, see what happens.

Cheers

Justin

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justin138

justin138

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Well folks, up at 5am for the Ringed One and with the 10" F5 Rev, 2X Barlow and 12.5mm eyepiece, there were discernable cloud bands and where the rings crossed the body, was so solid with a lovely shadow on the body. I'm sure I saw the Cassini Division for a split second as well

Seeing wasn't bad, the Moon washed the sky out a bit and there was a layer of haze up high.

I think I need more magnification as Saturn still looked a bit too small for my liking so I think a nice 6mm is on the shopping list.

Justin

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mike bacanin

mike bacanin

Posted
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hello justin

read the posts with interest. after the first possibilities of colimation and adequate cooldown of optics, the atmosphere,eyepiece choice and observer experience come into play. try to get a high quality eyepiece for your scope when you buy a 6mm. at f5 the eyepiece will probably play a big part in getting a good image. also the more you observe, the more you will see. i have seen cassini's in an etx 90 at about around 100x fairly easily in reasonable seeing, so i am sure your scope will do the job.

sometimes even a great scope struggles to show planetary detail if seeing is poor.however last year i looked at saturn through someone's 10 inch orion reflector (think was f 5) with radian 12mm and barlow and view was awesome. i am sure your patience will be rewarded.

regards

mike

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justin138

justin138

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Thanks for that guys, it was hazy high up so guess this played its part (and maybe also having been out of bed for 20 mins before starting observing with bleary eyes :rolleyes:)

Was looking at getting one of these http://www.scopesnskies.com/prod/90.html people seem to say nice things about them and the wider FOV is appealing too.

8 days to payday and counting............ :D

Justin

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Chubster

Chubster

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MOrning all...I too was out this morning to look at saturn and have to say I was a bit disappointed, could see her OK but she was tiny. What can I do to get "up close and personal" if anything. Was using meade 2x shorty with 12.4mm initially then went down to 10mm eyepiece supplied with scope. Still a wonderful sight but was hoping to get a little bit closer ! Thinking of doing some imaging but if that is the best I can get may have to think again :)

Chubster

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Kaptain Klevtsov

Kaptain Klevtsov

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The field of view of a Toucam is about the same as if you were using a 6mm EP, or so I'm led to believe, so the image scale would be about double what you saw in the 10mm EP, then add the Barlow and you're getting there. The trade off between image scale and being able to get the thing on the chip (and keeping it there) is the issue with planet imaging.

Captain Chaos

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russ

russ

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I had no problem seeing Cassini with the ED80 last year. But the rings have closed considerably this year, so Cassini won't be as easy to see. Throw in some naff conditions and that may explain why you couldn't see it.

As already pointed out, one key to planetary observing is spending a good amount of time at the eyepiece allowing your eye to adjust.

But also getting a good high power eyepiece. Orthoscopics are cheap and top notch but not particulary nice to use. Spending a lot of time at the eyepiece with one does not appeal. I ditched my orthos in favour of the Burgess/TMB Planetary Eyepiece. Sooo nice to use, excellent contrast, sharp and best of all for you, it was designed with dob users in mind. It has a 60degree FOV which is sharp edge to edge, with no lateral colour. Perfect! And it's reasonably priced too.....£69 from SCS Astro.

Regards

Russ

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MartinB

MartinB

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This might sound a bit wacky but you could try stopping down your scope. F5 is tough on the optics. Great for deep sky but you don't need that sort of speed for saturn. You could try cutting out a circle of cardboard and placing it over the front of the scope and bring you down to an aperture of 6". this would bring you close upto F8. Your contrast would suffer so the bands might not be as clear, and you would loose some resolution so the encke division wont be on, but any optical collimation problems would be sorted. It would be an interesting thing to try.

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Kaptain Klevtsov

Kaptain Klevtsov

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OK so the simple answer is to do with the focus of the 'scope. If you imagine the cone of light from your primary mirror coming to a sharp point, you have to put your eyepiece or camera at that position so each part of the image is a dot of very tiny size. You have to get the focus spot on because a little bit either side and you are moving along the cone of light. The disk shaped image gets bigger each side of the correct focus position as you will have seen down the eyepiece. You are looking at the cone some distance from the "point" of the cone. If you reduce the aperture the cone starts at the big end much smaller so the cone is more pointy. Moving the eyepiece or camera along the more pointy cone results in a smaller disk. It's easier to get good focus with a higher f/ ratio.

Slower refers to the time taken to generate an image on a camera. Block up most of the end of the 'scope and you get less ligt so it takes longer = slower.

Captain Chaos

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mark RD

mark RD

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I find a simple meade 4000 15mm eye peice showed up the Cassini Division very well though my 127mm refractor, not seen saturn this side of the year though.

I wouldent have thought an f5 scope would be too good on the planets.

RD

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