Novice with an 8" Dob

[Mrkex]

Hello All,

Firstly I would like to say thank you to all the people who reply offering good advice at a great price. I have been reading all these threads for a couple of months now and have had nearly all my questions answered. I bought a GSO 8" f/6 Dob as my first scope and have had a ball exploring the skies.

I have have found this telescope fairly easy to use, but when getting into higher magnifications it seems to loose alot of quality. I have collimated it, and I am wondering if the GSO plossl's are not good enough quality for higher mags? Around 200x mag and above, it gives fairly poor quality pictures I feel. But as I have never seen through any other scope I am not really sure.

I have been looking at purchasing a few new eyepieces maybe, a 9mm Nagler, and a 17mm Nagler 2". I was also wondering if a powermate would be an advantage over a TV 2x Barlow, I am not going to get into astrophotography so would a barlow be as good for observing only?

With my brother working in the US at the moment and a good exchange rate I feel like lashing out.

Does this sound like a good choice? Am getting too far ahead of myself? Am I dreaming?

Thanks again for all the past help

Regards Mark

[mental4astro]

Hi Mark,

:welcome: to IIS, mate!

Great first scope you've got there.

I see you've come across the archnemisis of us in the astro fraternaty- the atmosphere!

It is no accident that you can't get much more magnification than 200X. Typically this is the most you can get, and it doesn't matter how big or good quality your scope is. 300X is as good as things really get, and that is very rare. All this is because of thermal currents in the atmosphere becoming visible as power increases. This phenomenon has actually got nothing to do with the quality of your eyepieces.

Before lashing out on eyepieces, I'd suggest you go to a star party or an astro club meeting and borrow a few different eyepieces types. Big bucks on eyepieces doesnot mean best. Many folks only promote the "extraordinary" properties of extremely expensive eyepieces (one Nagler eyepiece will cost more than your scope). I don't agree with this philosophy. Clever eyepiece design selection and understanding human physiology will reveal better buys.

Barlow or no barlow? I'd say no barlow. Barlows put more glass between you and the object as far as I'm concerned. A good quality EP (eyepiece) will do a better job. There are a few really good choices out there, and cost less than $150.

Again, at a star party, good and poor eyepieces will all be there, and you'll be able to see for yourself how things work and go.

Astro clubs are listed in the "Our Community" heading in the top left margin. You can also see the "Star Parties" forum. I'll be heading to Katoomba Airfield this coming November 6. The Pony Club at Mangrove Mountain is another get-together near Sydney. Both of these are in the star party forum.

Mental.

[Mrkex]

Thanks for the sound advice Alex, I see what you mean. So I think I will cut the barlow and the 17mm eyepiece and just try to get 1 eyepiece for high mag, maybe a 7 or 8mm one but the reason I was swayed towards the naglers was because of their wide angle. I was hoping the angle would give me more viewing time on planets, because with the plossl's I don't get much time before I have to start nudging.

I will have to try to get out to one of these star parties soon. Sounds good.

Mark.

[Allan_L]

Hi Mark,
Good advice there.
I am a key holder at the Mangrove Mountain Pony Club.
We always publicise our next sessions on the star Parties forum.
And it is surprisingly close for Sydney siders.

I have a selection of Televues and Vixen and other eyepieces you can try in your scope next meet (early November). You will also find the darker sky of Mangrove Mountain lets you see more and get a better magnification than polluted Sydney skies.

Hope to see you there next month,:thumbsup: