Which Dobsonian??

ozfifer · #1 08-09-2007, 10:41 PM

Hi, Im new to all this and have been looking at getting a dobsonian for ease of use and price. Ive been on a few websites and bought a couple of mags, and am tossing up between the Bintel BT202 8", Gaun Sheng GS-680 8", or the Sky Watcher SW680 8". I would look at going up to a 10" model if it was around the $600 mark.

Any advice on what to buy or what i should be looking out for when buying a dobsonian would be greatly appreciated.
Im in WA so not sure if there are a lot of places who would stock the said telescopes.

Thanks.
Regards, Ozfifer

ballaratdragons (Ken) · #2 08-09-2007, 10:52 PM

Quote:

Originally Posted by ozfifer

and am tossing up between the Bintel BT202 8", Gaun Sheng GS-680 8", or the Sky Watcher SW680 8".
Regards, Ozfifer

Hi Oz, welcome.

The BT202 8" and the Guan Sheng GS-680 8" are the same scope. The only difference is that Bintel put a Bintel sticker on it.

But as far as service goes, there is some differences. One shop that sells the GS scopes don't service them (cheapest dealer). Bintel does (slightly dearer). Some people are happy to buy it cheaper and forget about service. Others are happy to pay the bit extra for peace of mind knowing that Bintel will repair and service.

It's entirely up to you, but they are the same scope.

As far as the Skywatcher goes, I don't think it comes with the better 'Crayford Focuser', which is a fantastic focuser. Many people without one upgrade to one.

As far as quality of optics, they are all pretty well identical.

I hope that helps.

xelasnave · #3 08-09-2007, 10:58 PM

Welcome to Iceinspace Ozfifer.
Whatever you get will be the right choice and yet you will then want yet another scope as ther eis always a bigger one somewhere... I have seen 10 inch scopes cheap in the buy and sell section herein.

I have the GS 12 inch (but want a 16inch) and they seem reasonable for the price as I expect most will be...in fact I recon for the money they are excellent.

Someone else will have to help with a store close by but shipping is no big deal.

A dob is best for visual in my view as it is easy to get around the place... eq mounts are useful for photos and goto if you must.

Personally I would get an 8inch and after a year you will want a 12 or a 16 but an 8 will get at most everything you will seek until you gain experience..

I add that so much of my viewing is done with a 80mm as it is easy to set up ... once you know your way around small is not that bad.

Good luck and again welcome.
alex

ozfifer · #4 09-09-2007, 12:31 AM

Thanks for your advice xelasnave. Ozfifer

ozfifer · #5 09-09-2007, 12:35 AM

Hey ballarardragons. Thanks for that advice. Are the dobsonians able to be fitted to a tripod if required at a later stage , or are they only designed to be that close to the ground.
cheers again , Ozfifer

ballaratdragons (Ken) · #6 09-09-2007, 12:39 AM

Dobsonians can be mounted on an EQ mount. Obviously the bigger the scope, the bigger the mount needed, but with an 8" you won't need a mega-buck mount. An EQ5 will do as a minimum.

The Dob actually started it's life on an EQ mount. It is really called a 'Newtonian Reflector' telescope, but since John Dobson made the dobsonian mount popular, many people tend to just call the scope a 'Dob'.

Quite a few of us have our reflectors mounted on EQ mounts

luka · #7 09-09-2007, 02:43 AM

Hi,
The two places in WA that I know of are
http://nvt.com.au
http://www.btow.com.au/ (no online prices)

Also Andrews is offering free shipping in Australia at the moment.
http://www.andrewscom.com.au/site-section-10.htm

You definitely want to get one with the Crayfor focuser. You may also need a collimating tool.

ozfifer · #8 09-09-2007, 10:52 AM

Hi Luka, Thanks for that. I was up at that store yesterday, didnt have a great selection to look at. Excuse my ignorance but what is a collimating tool??.
Cheers Ozfifer

Dujon · #9 09-09-2007, 11:32 AM

'Morning, Ozfifer. Do you play the penny whistle?

A collimating tool is a device that assists you to align your mirrors and focussing tube. Anyone with a reflector type telescope will gain from owning one. Don't be put off by the jargon; 'collimate' is a word that simply means 'to bring into line'.

You can make such a tool yourself with the cannister for 35mm film or you can buy a 'Cheshire' or 'Laser' unit from a telescope shop. The Cheshire unit involves sighting through a pin hole in the construct whilst the laser usually relies on a laser beam (very low power) being emitted from your focuser (that's the eyepiece holder) to the secondary mirror, down to the primary mirror and then back via the same route.

Correct alignment is important. It's not hard to do but at times it can be finicky.

I suspect that if you put the word 'collimation' into the search facility (see top of this page) you will come up with a wealth of information.

knicholas · #10 09-09-2007, 02:54 PM

Hi Ozfifer,

Having very recently travelled the same path, I eventually settled on a 10" GSO Dob from Andrews Communications (see Luka's message). I was impressed with their help and service, the scope was here in 4 days.

If you you opt for the premium crayford version of the 8", you should get change from your $600

, and the freight is on them - about $300 to our end of the world.

Good luck,
Keith

rmcpb (Rob) · #11 09-09-2007, 04:59 PM

Whatever you do make sure you get the one with the Crayford focuser, its FAR superior to the old R&P focuser.

ozfifer · #12 09-09-2007, 06:33 PM

HI Dujon - The penny whistle is my favourite instrument!!!. So would the seller of my scope fit this laser for aligning or do i do that.
Thanks for your advice.

cheers, Ozfifer

ozfifer · #13 09-09-2007, 06:35 PM

Hello Knicholas, Thanks for your reply. What is the difference on the 8" or 10" is it just the amount you can look at?. Sorry for the ignorance, but just need to know if a larger diameter is really necesary.

cheers, Ozfifer

stellarquest · #14 09-09-2007, 06:42 PM

Hi and welcome Ozfifer. I bought the GS 8 and never looked back. It was my first serious scope, and remains much used today, even with the addition of a LB 12. Was going to sell the 8 but adter spending a supposedly last night with it, had a talk with my Minister of Finance, household division, and the rest is history. The GS represents excellent value for money, and, believe it or not, I have only had to collimate four times after quite a few years of regular sevice. Again, welcome, and remember, there is no such thing as a stupid question, only stupid people who think themselves above answering properly.I should hasten to add that I have never seen or had that type of person on this forum.

rmcpb (Rob) · #15 09-09-2007, 07:54 PM

The 8" and 10" show much the same objects BUT they will be brighter in the 10" so many people prefer it as a beginners scope. However, the 8" is an f6 and the 10" is an f5 which is much more fussy about collimation.

Not so long ago the 6" f8 was considered the beginners scope but now most people would say at least the 8". I think it is a great beginners scope because its a bit easier to set up and it leaves a natural upgrade to the 12" which delivers an extra magnitude of viewing over the 8".

Just some things to think about.......

Dujon · #16 10-09-2007, 10:33 AM

Quote:

Originally Posted by ozfifer

HI Dujon - The penny whistle is my favourite instrument!!!. So would the seller of my scope fit this laser for aligning or do i do that.
Thanks for your advice.

cheers, Ozfifer

It's probable, or at least possible, that your supplier will collimate your device before despatching it to you, Ozfifer. The on going collimation will then be up to yourself. The device (whichever you use) simply fits into the focuser - where your eye piece normally sits - and is used solely for collimation purposes. Once you figure that you are pretty close then you take the 'scope outside in the dark of night and do a 'star test' with one of your eye pieces in place (i.e. the collimator is sitting inside on the dining room table and not in the 'scope); this involves looking at a bright star, not a planet, and deliberately moving the image out of focus - both sides. In theory you should see a dark 'dot' surrounded by a halo of light. The dot should look centred within the halo and the halo circular.

Don't be put off by all this information, as I've already mentioned it's finicky but not hard.

P.S. I guessed your penny whistle interest from your 'user name'.

ozfifer · #17 11-09-2007, 06:36 PM

Thanks to everyone who shared their info with me. I will get the GS from Andrews Comm, although they are sold out at present.

Thanks again.

Regards, Ozfifer

GrahamL · #18 11-09-2007, 07:42 PM

try mat at
http://www.telescopes-astronomy.com.au/
listed at $580 and a little closer shipping wise to you
upgrades cost a little more whoever you buy from .

Mr. Subatomic · #19 15-09-2007, 09:16 PM

Quote:

Originally Posted by ballaratdragons

The BT202 8" and the Guan Sheng GS-680 8" are the same scope.

I'm pretty sure SkyWatcher is made by the same manufacturer.

Starkler (Geoff) · #20 16-09-2007, 10:31 AM

Nope, Skywatcher are made by Synta in China, whilst G.S.O. is based in Taiwan.