Observing saturn with 8" dobsonian

[HSK]

Hi all.
I was wandering how well you can see Saturn with 8" dobsonian and with its standard 10 & 25mm eye pieces. I observed it once and it was no clearer than bright star. I could have been looking at the wrong object but I used star walk iPhone star finder. I was a bit dissapointed not to be able to see any ring.

Thanks

Tom

[Kevnool]

You should see Saturn quite well ........well put it this way you wont miss it.

Even see it in a 4 inch as well.

Yep no problems there.

Cheers Kev.

[SteveB]

Hi Tom,

I have been able to make out the rings on my little 60mm Tasco, they were very small though. I am looking at buying an 8 or 10" Dob & look forward to seeing Saturn through it.

[astro744]

Saturn is rising after midnight and not at its best (hightest altitude) until dawn. Tomorrow morning it will between the Moon and Spica in Virgo. It has a yellow appearance and similar brightness to Spica.

The rings are quite closed (closer to edge on) but quite visible in your 8" telescope particularly with the 10mm eyepiece. If you didn't see rings then it may be possible you had a different object in view.

[HSK]

Thanks for the replies all. I'll be staying up again to see if I can see through cloud tonight.

Thanks

Tom

[Esseth]

Yeah i have been trying to get my first look at it for the last few weeks, but its been cloud and rain every attempt lol

[floyd_2]

The first scope that I ever owned was a 4" Tasco reflector, maybe 20 years ago (0.96" eyepieces and all). I had no idea how to set it up, or how to point it at anything of note. The first object that I ever managed to point it at turned out to be saturn. There was no mistaking it, rings and all...and I was hooked.

In an 8" you'll see plenty, and there'll certainly be no mistaking what you're looking at. Just make sure your scope is collimated and you'll be on a winner!

Dean

[HSK]

I was looking at jupiter and orion nebula just than and cloud... Hopefully it won;t be at 2 in the morning. Just because of Saturn, everyday I stay up until 3 in the morning and wake up at midday!!! :) I'm getting used to it.

[DavidU]

Try a 5mm if the atmosphere is steady.Keep the scope outside for as long as possible to get the mirror as close as possible to the air temperature.
A cool telescope gives better images.
cheers !

[mental4astro]

A mate of mine, and fellow IISer, Hickny, had an 8" f/6 dob until recently. We spent many hours using and comparing objects with his scope and my f/4.5 17.5" dob. Saturn amoungst them.

As a visual experience, I actually prefer the image provided by his 8" dob. The clarity of detail provided by the slightly slower scope outperformed the overly glary image in my big dob.

Sure, the big dob did show fainter moons, but not by much. On one occassion, where my scope revealed 6 moons, his showed 5. Most impressive.

Titan, Saturn's biggest moon, is the easiest one to spot, especially now that the rings are still quite shallow in inclination. Make a couple of little drawings of what you see with your two eyepieces, noting all the stars in line with the ring system. Then come back to Saturn after 4 or 5 hours and compare your drawings to the new view. Even the next night is OK as the Planet will not have moved too much compared to the background stars. More experience will begin to reveal more.

My first view of Saturn was by chance while tracking Mars some 27 years ago. I think the echo of my 'WOOHOO' can still be heard! This was using my 50mm Tasco refractor at 30X! Absolutely unmistakable. You will surly have no problem with your 8" dob.

[HSK]

I'm excited but the sky better return clear by 2... Thanks for all the informations

Cheers

Tom

[erick]

Tom, I think you weren't on Saturn. In an 8" dob the disc is very clearly seen, as are the rings. Lovely cream/yellow colour as well. Saw it the other night at a Summer School at 4am in an 8" SCT. Got all the "Oooohs and Aaaaahs" from the first timers who got up at that time. I also had it in a 4" short tube refractor. A lot smaller, but just as distinctive.

[HSK]

Thanks I guess I was just looking at a star. In about 2 hrs later I'll be out to observe Saturn and mars. I already got the telescope out too cool.

Hope cloud stay away!!

Thanks

Tom

[snoozy]

Happy New Year :)

Hi,

My name is Susie and have just registered. I love astronomy and studied this topic a few years ago now. During my studies of the moon, a particular terminology has eluded me and wondering if anyone out there could help me.

My question is: What is the name given to the effect of the moon's edge when not a full moon? The view through a telescope provides such a fine detail of the craters and the curvature (spelling). I do remember from my studies that there was a particluar name for it. Thankyou in advance.

My friend has just recently obtained a dobsonian mounted telescope. We had a fantastic night on New Years Eve observing the moon.

I look forward to discussing topics of astronomy.

Seeya,

Susie

[HSK]

Hi Susie!
Will you be observing tonight? If it's not cloudy you can see mars and saturn now. I'm just waiting for the misty cloudy to clear.

Tom

[Visionoz]

Susie

Welcome to IIS

The term you are thinking about would be probably be the "terminator" where dark & light meets when the moon is not full

Cheers
Bill

[HSK]

Ah I give up! The clouds are going nowhere. Well at least I had fun with my dogs. Will have to try again tomorrow.

Tom

good night... Morning :)

[floyd_2]

...and I thought Sydney was the only spot with endless cloud!

Dean

[Barrykgerdes]

About 20 years ago I bought my first telescope. A Tasco 114 mm reflector. It showed saturns rings but quite small at about 60 x mag. Any greater mag was blurred (poor eyepieces). I think you must have missed Saturn

Some months later I went to my first Macquarie Uni open night and looked through an 8" Dob. The view was magnificent at around 250 x mag. I was hooked I got myself an 8" Dob kit from Astro Suppliers and I have been spending all my spare cash on astronomical gear since.

Barry

[erick]

Hi Susie :welcome:

Yes, it's the "Terminator" and, though it was not there on New Year's Eve, it'll be back!

Full Moon on that night would have been interesting but, apart from putting a purple dot in front of your eye for several minutes :D, full Moon is only good for seeing the ejector rays from the three large relatively more recent craters. Better to watch the Moon through its phases and concentrate around the terminator to really see the full wonders of the Moon.

[HSK]

it should clear during the week here I think and hope.

Tom

[Esseth]

Yeah i am hoping for it, as i am going way out of the city and i really want to take the dob out for a spin under dark skies... Crosses fingers.

[Zzapped]

Got my first view of Saturn last night.........unmistakably Saturn and I could make out the rings, my Question is, Im just using the 10mm Plossl that came with my Dob, would a Barlow make a significant difference to what I can see ?

Cheers

Z

[erick]

Under very good seeing conditions, Steve, a 2x barlow with your 10mm plossl would give a larger image which may well afford more visible detail. Sadly, such conditions might occur on a handful of nights a year. However, it is not easy to predict exactly which nights and at what times during those nights this occurs - hence this hobby is always an exciting chase in pursuit of that magic night! And you want that barlow in the eyepiece box for that very night! :)

[mental4astro]

G'day Z,

IMO, I would rather have a dedicated 5mm eyepiece than a barlow. Less glass = less loss of light. You would be better of with a decent quality EP, and they don't need to break the piggy bank. You can also throw in a wider field of view with a good EP, meaning that the object stays in view for longer as it drifts across the field. You will then be value adding to your scope by improving your EP collection.

It also means that you will have less items to fiddle around with in the dead of the night.

If you would like a couple of recommendations, PM me.

Yes, a barlow can help, but...

[Zzapped]

I must admit, im a bit confused by all the eyepiece terminoogy here, ive gathered that the trade off for greater magnification is less field of view between the 10 and 25 mm plossl's that I have, so what would be the better option for that next step up, is there such a thing as a 5 mm with a wider field of view that my 10MM ?

Cheers

Z

[floyd_2]

There's an eyepiece calculator here if you're interested:

http://www.davidpaulgreen.com/tec.html

It gives you Field of view, exit pupil, magnification etc for a range of common eyepieces. If you want a greater field of view, you could switch to a Televue Nagler eyepiece.

Using the example data on the page above, just change the Televue Nagler to 5mm, and the Televue Plossl below it to 10mm focal length and press COMPUTE.

You'll see that the true field of view for the nagler works out to be the same as the plossl. However, you're getting twice the magnification with the nagler. Naglers come at a price though.

Remember, as Erick noted, that the highest magnifications are only useful on the best nights which you may find to be few and far between. There's always a balance of magnification vs actual image resolution and a lot of the time you'll find that a bigger image isn't better. Imagine if you're viewing saturn with a 10mm eyepiece and its just the tiniest bit fuzzy on a particular night. If you double that magnification, you're also magnifying that fuzziness.

Most visual observers end up with a collection of eyepieces of various focal lengths to best suit their scope, and maybe at least one barlow to augment the collection (one barlow is cheaper than buying twice as many eyepieces). If you build your eyepiece collection properly, and throw in say, a 1.8x or 2x or 2.5x barlow, you'll hopefully never double up on magnifications between eyepieces. For example, if you have a 5mm eyepiece and a 10mm eyepiece, and a 2x barlow...the 10mm eyepiece in combination with the barlow would make your 5mm eyepiece a waste. Perhaps a 15mm eyepiece (or thereabouts) would be better. That way you would end up with 10mm / 5mm for one eyepiece, and 15mm / 7.5mm with the other. That would give you a range of 4 quite different magnifications. Of course, your economy would increase as you purchased more eyepieces.

I was always quite careful when I purchased naglers and panoptics etc, which are quite expensive, that I didn't double up on magnifications unnecessarily. I ended up with 7mm, 9mm, 12mm, 16mm, 22mm and 27mm eyepieces. This gave a pretty good range of magnifications with a 2x and 1.8x barlow. That way I could fiddle around a little and get the perfect magnification for an object for the seeing conditions on any given night.

Dean

[stephenb]

Hi Tom, as others have already pointed out, you should see the disc of Saturn and the thin rings. The rings are close to edge on from our perspective at the moment. Try to pick yourself up Astronomy 2010 (I know Bintel still have them), if you don't have it already! As Erick said, I think you were looking at a different object (a star).





Hi Suzie and welcome :hi:





Yes Steve , that's generally the go. The smaller the number of the eyepiece (25mm... 10mm... 5mm...) the higher magnification, but the compromise is that there is less light entering the eyepiece and therefore a dimmer and less-clear view. As Dean, Erick and other have said/will say, the rule is "more magnification is not always better". Let us know how you go. :thumbsup:

[HSK]

Yeah, I think I got the idea. I was looking at the wring one. You guys are embrassing me. :face:

thanks though :)

Tom

[erick]

I stared at Mars for a while one night some years ago soon after it had risen. What's it doing there and it looks a bit odd? Only had binoculars with me. Half an hour of head scratching and looking later. Damn! Aldebaran! Duuh!

[HSK]

Haha just like me. I believe I was looking at spica instead of saturn. It was the only one poking out of cloud and my star finder said it was there. The saturn must've been hiding behind the cloud next to spica. :)

Tom