Best eyepiece for Saturn.

[srv]

I finally got to see Saturn last night with my 2week old 10" dob
and was a bit disappointed.

Started out with 25mm eyepiece and then progressed to my 6mm.
With the 25mm the image was great although quite small,
with the 6mm it was very hard to see into the smaller hole eyepiece
and the image was a little blurry.

I guessing that I'm seeing why the GSO eyepieces are maybe just
average and that's why people have said to me that I would later on
want to upgrade/purchase new eyepieces.

That being said, what's the best eyepiece (magnification) to use
for eg: Saturn ?

Also should I be looking at getting a new eyepiece (good quality)
or just get a 2" 2x barlow to use with my 2" GSO 32mm eyepiece ??
I enjoy looking through the 2" 32mm GSO eyepiece as it has a nice large
easy to see viewing angle.

thks.

[jjjnettie]

Hi,
The 2" GSO Barlow has an adaptor so you can also use it with the 1.25" EP's.
I reckon you'll get view you want with your 15mm ep barlowed, and on a very good night, which is pretty rare, try the 9mm ep.
While the GSO plossls aren't top quality pieces of glass, they certainly aren't as dodgy as some may make them out to be.
"Serviceable" is a good word to describe them.

[rmcpb]

Matt,

Saturn is a real challenge as it has very little contrast so don't expect too much apart from the major cloud bands. Can you see the Cassinni Division in the rings? If so you are not doing too bad especially as the rings are more side on this year. This is a good test of your seeing, mirror temperature and collimation.

If you are looking at a barlow I will go a bit against the normal advice given here and suggest that you get an apochromatic 1.25" 2x barlow like the Orion Shorty Plus or Celestron Ultima. Combine one of those with your selection of 1.25" lenses, especially the 15mm,and you have a great range.

Some points:

Make sure your mirror is cooled to ambient.
Use a fan on your mirror
Collimate your scope as best you can


Planetary/luna observing is great but can be very frustrating at times.

Cheers

[erick]

Hi srv

With your 6mm GSO plossl, you are just over 200x. At that level, the seeing conditions probably start to blur out your image. On those rare nights of good seeing, you may be very pleased with the view. (By the way, are you waiting until Saturn has reached a good elevation and not looking through too much atmosphere?)

I wasn't very happy with my 6mm GSO plossl, solely from the eye relief which was so poor that I could not get in close enough to see the whole field of view. Apart from being better glass, I was happy when I got my Vixen LV 6mm - great eye relief and could see the entire field of view.

Yes, there are plenty of reasons to have a barlow available. One reason is that, with a barlowed eyepiece, the eye relief improves. That can make that 9mm plossl much easier to see through. 9mm + 2x barlow gives you 278x in your scope. Very useful magnification when the seeing is good

As Jeanette said, the GSO 2" 2x barlow comes with a 2"-->1.25" adapter for the smaller eyepieces. They seem to be reasonable workhorse barlows for an economical price.

Be ready with some counterweights for your scope (eg. speaker magnets) - the barlow plus the 26mm kellner will make it top heavy.

[erick]

Yes, more fun is to wait a few months until Jupiter is well up, then target that at high magnification. Look for a moon transit (or occasionally a double moon transit). Watching for the shadow of the moon(s) move across the surface is a good test of you equipment plus seeing and quite exciting! :thumbsup:

[mrsnipey]

I used my 8-24mm Baader Hyperion zoom (at 8mm) with a 2x Barlow that I got with my dob on the weekend and the views of Saturn were spectacular.

Moves across the field of view quite fast but I had the nudge down pat by the end of the night. Damn mosquitos nearly bled me dry though.

The cheap plossl eyepieces I got with the dob don't even come close at that magnification. The 15mm and 25mm are clear and sharp without the barlow but Saturn is just too small to really appreciate it.

It's a big step to take buying a good eyepiece (especially the first one) but I don't regret it at all. Not with views like that.

[rider]

I was also looking at Saturn this week (prior to the standard Brisbane 100% cloud cover)

I tried a number of coloured filters to improve the view - then I accidently put a nebula filter on and... WOW!

Saturn was close to the full moon, but I still got a great view.

Rider

[OneOfOne]

maybe up to a magnification of 1x per mm of aperture? Or a little less, something around 200-250x should be usable under reasonable conditions for your scope. About 2x per mm is about the best on the best night...which is not going to happen very often.

Expecting much more than this is like thinking your car is actually able to get to the fastest speed indicated on the speedo...without having to drive over a very high cliff :lol:

[Solanum]

I was looking at Saturn at around midnight on the 24th and the seeing here in Mildura that night was excellent (best I've seen in months - it's been awful this summer).

I could clearly see the Cassini division using my 6 mm eyepiece and didn't need to resort to averted vision. I could also see the (limited) variation in cloud colour and darkness reasonably well.

I hated the GSO 6 mm Plossl, which is why I replaced it early. The minute eye relief and tiny eye lens make using it unpleasant. However, this is inherent in the Plossl design. I think a 9 mm Plossl is the lowest focal length that is comfortable to use. If you do replace your 6 mm don't get a Plossl if you don't like the one you've got! On the other hand, I have found this summer, that the seeing has very rarely been good enough to use the 6 mm, so beware that if you spend a bit more money like I did, you won't use it all that often.

On the 24th I played around with my GSO 2x Barlow as the seeing was so good. My 9 mm Barlowed gave views with similar detail to my 6 mm on it's own, but with a larger image. My 6 mm Barlowed, was a wonderfully large image, but probably showed less detail than when not Barlowed.

Sorry if all that is a bit waffly, but hopefully it gives you some idea of expectations from another relative newbie.

[Jen]

:hi:Hi im from Swan Hill do u have any get together nites in Mildura oh and yes that was a bit waffly u got me all confused lol im still not sure which eyepiece ended up being the best :thumbsup:

[Solanum]

Jen,
There is a Mildura astronomy club, 'Oasis Stargazers Club' the not especially informative website is here: http://mc2.vicnet.net.au/home/astrogroup/web/index.html

It looks like the person running it has recently changed as it was run by a friend of a friend, but now lists someone else as the contact. They have monthly public viewing nights. However, I have never got around to going along or joining (three small kids), so I know no more about it.

As for the best eyepiece for Saturn, I think I was saying the same as the others- there isn't one! When it comes to the planets you want as much magnification as you can, but the 'seeing' is rarely good enough for more than 200x (a 6 mm eyepiece with my scope), recently it has rarely been good enough even for that. Magnification is calculated as focal length of scope divided by focal length of your eyepiece (in the same units). e.g. my 1200 mm focal length scope with a 6 mm eyepiece gives a magnification of 200x (1200/6 = 200).

[Jen]

Hey i found it cheers thank you :thumbsup:

[janoskiss]

IME, the best EP for Saturn in your scope is more often than not a good high contrast 12mm in a high contrast 2x barlow. Note that most 2x barlows will often function as 2.2x.

This yields a magnification of around 220x is high enough to see a lot of detail (just about as much as your scope can show you if you have a good keen eyesight), but low enough so that the image still looks okay in moderately good seeing.

The EP-barlow combo which I found gives the best view is 12mm UO HD orthoscopic in a 1.25" (or 2") Orion Deluxe 2x barlow. These barlows are especially well suited to planets with their unique internal baffling yielding the highest contrast IME. (I've also got Televue, GSO 1.25 and 2" barlows, and have used/owned most barlows, incl Powermates, on the market with few notable exceptions: TMB and Zeiss.)

My second choice is the same barlow with a 12mm Pentax XF. This EP is almost as good as the HD ortho ito sharpness and contrast (almost) while also giving you and your guests comfy eye relief (enough for eyeglass wearers) and a nice 60-degree wide field of view.

[mark3d]

we first saw saturn in the 10" dob with a 26mm (48x), like you i was a bit disappointed.

i bought a 2x barlow (GSO ED for $80) and on advice from this forum i bought a 17mm Baader Hyperion (75x). With the barlow that is 150x and the view is much more impressive, although still not much in the way of details. i thought i saw the cassini division but wasnt sure if i was imagining it or not ;) i also think i saw some detail on mars one night.

i want to go a bit higher, might buy something like a 12mm (105x and 210x barlowed) .. i think that would give pleasing results, i expect i would see the cassini division.

if i could ever get use of 8mm or 6mm barlowed (317x or 423x), i would be seriously happy - would see some very nice details.

[AstralTraveller]

Some thoughts on planetary viewing.

Magnification is overrated. We all know that cheap scopes advertising "Will magnify 568422x" are pieces of bovine excrement but even in a real scope there can be too much of a good thing. I know very experienced observers who reckon anything over 150x is wasted. I don't totally agree but there are certainly only a few nights when much over 200x is usable. I'm thinking of a 25cm scope but he was referring to much larger scopes. Apart from the fact that magnification also magnifies all problems (eg seeing and scope shake) there is also the issue of the resolution of the human eye. I read somewhere that the eye can resolve to about 1-2 arc minutes (1-2'). Now suppose your scope can resolve 1 arc sec (1"). If you magnify the image 60x the 1" now appears to be 1'. Any more magnification just gives you a better view of the blur. Of course if you eye can only resolve to 2' you would need 120x to reach your limit. I don't think that is the whole story but it is a consideration.


Personally I don't like barlows. I know that puts me in the minority, and I haven't used the best barlows, but I would opt for a shorter eyepiece. Barlows also contravene the next 'rule' which is..


The fewer pieces of glass in the eyepiece the better. There will be less scatter and less internal reflection. Yes good 6-8 element eyepieces keep these issues down but they can't compete with good 3-5 element eyepieces. A few years ago TMB was making 'supermono' eyepieces specifically for planetary viewing. They had three elements with no gaps between them, so only 2 air-glass surfaces. Their apparent field of view was only 35 degrees (BTW anyone know how to do a supscript around here??) but they were supposedly the bees knees for planets. They cost serious $$$ and aren't made any more. Then there are orthoscopics with 4 elements and a 45 degree fov. They are supposed to be very good but they are still on my wish list so I can comment. They are also supposed to be less prone to ghost images (the explanation is very long).

Years ago a mate and I were observing early one morning when the skies were very very good. I had my 25cm f8.2 and he had a 33cm f4.5. Saturn had got high enough to warrant losing my dark adaption so I was admiring the view in my old Celestron 7.5mm silver-top plossl and commented on just how good it was. So my mate loaned me his 7mm Nagler. I didn't want to say anything so I let him do the A-B comparison. We agreed that the plossl was better. "Ah, but in a shorter ratio scope the Nagler will be better." So we tried them in the 33cm scope. Same result. Now the Nagler is a brilliant eyepiece and I lust after them but for this job less is more.


Two eyes are better than one. I recently bought a Williams Optics bino-viewer. It took a while to get used to it, and I haven't even used it that much because my wife finds it difficult, but on the moon and planets it is great. It certainly has issues like unequal illumination of the two eyes and internal reflections (and I'd love a Denkmeyer) but you can get really good views with it.


If you have a newtonian - flock it. Flocking refers to putting very black light-absorbent lining on the inside of the tube to improve contrast. It is mostly considered for deep-sky but it helps reduce scattered light when viewing bright objects and so improves contrast which help with subtle surface details. There is an argument that flocking the whole tube affects cool-down time but you should certainly flock the area opposite the focuser and consider doing the inside of the focuser tube as well. For the same reason, also get a decent length dew shield/light baffle on the top of the tube.
Sorry this has got so long but I can't even write my astro shopping list without producing an essay :D.

Happy viewing.