What to buy? - 8" dobs

[Splotch]

Hi everyone,
I was just on the Australian part of astronomyforum.net asking for advice on a new 8" dob and realised no one was from oz. They were all very helpful but i thought i'd try finding someone with some knowledge on the Australian market and where to buy for best value etc.

So the best deals i could find for what i'm after was this:

http://www.ozscopes.com.au/ozscopes-8-dobsonian-telescope-free-6mm-eyepiece.html

= $399 + $140 Postage

or this:

http://www.andrewscom.com.au/site-section-10.htm

That website is horrible but if you scroll down it's the GS-680 8" dob for- $499 + $70 Postage

Now i don't really know a whole lot about all this stuff but i do know GSO's are quality scopes but if anyone could point me to a better deal or has any feedback or recommendations on what i should be getting, that would be great!

Should i be adding anymore eyepieces, filters etc to the package or anything like that? Or is the included gear enough for a beginner?

Cheers

Ryan

[atkinsonr]

Hi Ryan,

I've got an 8 inch GSO dob and they are indeed fantastic. Mine says, "Guan Sheng" on the OTA. It was a gift but I think it was $399 from Andrews on sale last December. In the pack was a 8x50 finderscope (also very, very good) and a good selection of GSO plossls (no complaints there either).

Both Bintel and Andrews are great to deal with but are both in Sydney.

Before you pull the trigger have a look on the IIS classifieds? You might find something closer to home.

rich

[rustigsmed]

Hi Ryan,

If you get a GSO newtonian scope i'd recommend getting new springs (which sit under the mirror) like these ones http://www.bobsknobs.com/Newt/page45/NewtPri.html (http://www.bobsknobs.com/Newt/page45/NewtPri.html) you should also look at getting a collimation tool; http://www.bintel.com.au/Accessories/Collimation/44/catmenu.aspx i'd suggest either the Orion Collimating eyepiece or a barlowed laser like the Glatter 1.25" Barlowed Collimator. I've heard its best to avoid the non barlow lasers.

I wouldn't worry too much about other eyepieces yet (you get 3 with the scope), perhaps a barlow lens or 2.5x powermate.

best of luck!

cheers

Russ

[Splotch]

Thanks Rich, sounds like you got a great deal there.

Had a look on the classifieds but nothing really stuck out. I have also found an extra 2 candidates that are close to home:

http://www.sirius-optics.com.au/skywatcher_dobs.htm

http://www.sirius-optics.com.au/orion%20dobs.htm

The 8" SW is $475 after enquiring about it over the phone and the orion is currently out of stock (apparently waiting for new ones next month).
So i could go and pick these up without the postage fee which is good.

Which is the better buy for an 8" Dob? - Guan Sheng ($570), Skywatcher ($475) or Orion ($500??? + >1month wait)

Thoughts?

[rustigsmed]

Hi Ryan,

The Orion and Skywatcher are essentially the same as they are made by the same company.

I don't think you will go wrong with any of the scopes, although in my experience the GSO scopes need more tweaking especially with maintaining collimation.

Another thing you should get before i forget is upgraded knobs for the secondary mirror. That will be for either choice you get.

Cheers

[Splotch]

Ah cheers russ, so i would probably regret not buying a collimator? Looks like an important tool for allignment/focus.

Im not entirely sure how any of this stuff works yet so bare with me. Just a few more questions before I go buying anything:

How do the upgraded knobs help? Do they make it easier or something?

Will the barlow lens simply increase the magnification?

and this will be my first scope so should i throw all the above into one bundle or buy them later on down the track when i am more experienced?

Cheers guys

[rustigsmed]

Collimation is important, if you are lucky the scope will be in a pretty nice alignment when it arrives, however if it isn't then you won't be getting nice views of things like the planets, you just wont get a sharp focus. over time the mirrors move out of alignment more and more, degrading the view. most people will collimate their newtonian scope before use, if you do that, then it only takes a minute or so to do (no chore at all, just part of setting up really) and will take minor adjustments.

Thats why stronger springs are better, the mirror moves less ... the factory ones in the GSO particularly are sub par (although i have not used the 8"). I have a 12" GSO and a 12" Skywatcher, and the skywatcher did not need upgraded springs, whilst the GSO was useless. but these mirrors are much heavier than the 8" and they may not be a huge problem but something to do down the track.

The knobs for the secondary just make it easier and less risky, they enable you to adjust by hand rather than using an allen key ... which if you drop could damage the primary mirror.

So i'd advise getting the secondary mirror knobs straight away, and a collimator soon after. See how bad the mirror goes, and decide if you want to upgrade the springs. some people just use bunnings springs.

I wouldn't see any of these things as deterrances in buying any of these scopes, you will get nice views in all of them but i find it will eradicate annoyances you will have with the scope and be more likely to enjoy the viewing. I would get these things before a barlow or a non standard lens.

a barlow increases the magnification of an existing lens yes.

and ... i wish my first scope was an 8" dob you've made a great choice in beginner scope :thumbsup:

[CJ]

Ozscopes advert on the right offers free P&P on orders over $100.

[Splotch]

Wow thanks mate, plenty of information there!

Ha yeah well i was looking at buying something a little cheaper but i was convinced into getting an 8" dob as it will apparently keep me happy for years and they're good value.

Well now i am finally feeling good about getting the skywatcher and ill grab the secondary mirror knobs and maybe a collimator if i can get a good deal, otherwise ill get it later with the other accessories as you have said.

Thanks for the help!

[Splotch]

Thanks Chris i didn't notice that there.

Strange though, i just called them and they said that offer doesn't exist so im going to steer clear of ozscopes for now

[CJ]

"Strange" is quite polite. :thumbsup:

[barx1963]

Ryan
I have dealt with Andrews, Bintel, and Sirius Optics and have had no issues with any. GSO dobs are very good for the money and 8" is a great place to start.
Collimation is one of those things that I think are designed toi frighten beginners away from our wonderful hobby. The important thing for a beginner is not to get too hung up on it. Collimating a scope is an exercise in diminishing returns, so going from a scope really badly of of whack to one roughly collimated yields a very noticeable increase in image quality and each time to tweak it a bit closer to perfection the improvement is less. On an 8" at f6 getting collimation pretty close will do to start. It makes no sense spending an hour collimating a scope when that time is better used actually using the scope. NOTE I am not saying don't collimate, just be realistic about the benefits.

As collimation tools, if thinking of a laser one, just be aware that they are really only useful as a final tweak. A good guide to collimation without a laser is here http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide .htm and it certainly applies very well to an 8" dob.

Springs and knobs can be upgraded, certainly the springs on the GSO 12" should be. The 8" mirrors is much lighter so from what I have seen the springs are not so bad in the GSO. Knobs simply make the process tool free. If using a tool to collimate the secondary a good tip is tape a bit of cord to the tool and tie it round your wrist so you dont drop it on the main mirror. You also collimate with the tube horizontal but I am not a fan of this for two reasons 1 it can be uncomfortable and 2 the clips holding the primary are not tight, so the mirror can move slightly unless the tube is above horizontal.

Malcolm

[atkinsonr]

I would drive down to Sirius and have a look but I see no reason to go past the $475 SW. AFAIK the SW and GSO are the same OTA.

I can't think of a good reason to go pass this up for one of the other two.

[barx1963]

Not correct. The SW is made by Synta and the GSO is made by Guan Sheng, when you examine close up they are quite different. That said an 8" dob is pretty basic and they are pretty similar.
Some confusion arrises as GSO scopes are very often rebranded, Zhumell in the US and Bintel here in Oz. Also Synta make other brands mainly Saxon as far a dobs are concerned.

Malcolm

[Tejas]

i can recoomed if you are going to sirius optics to go a little bit further and go to astro pete's. pete's has the 8" skywatcher full tube for $475

pete is passionate, non-pushy and is happy to give advise, even if it means the sale is for less money. he will show you how to collimate your scope and is always happy to have a chat if you are in town and can even point you to anastronomy group in your area.

i'm not affiliatd with astro petes i'm just an extremely happy customer

i have heard some sorys about pushy sales people at sirius.