first scope

James Kirk · #1 22-05-2007, 09:37 AM

Hi All

Same old question you hear all the time, which scope to buy.

Well I have read a few threads here and learnt a lot but have a few questions if anyone is able to assist.

I am not into astronomy (not yet anyway) but I do have a caravan and spend many nights away staring at the stars and have 2 young daughters asking me lots of questions about the stars that I cannot answer, so I would like to see more and no more (as fathers out there know that we have to know the answer to every question coming our way).

I have decided on an 8" Dob.

I am looking at either the skywatcher sw680 or the Guan Sheng gs680.

My questions are?

Which of these is the better? pros and cons of each as the price delivered to Perth is similar.

Will I see more than what I can see with the naked eye (ie not just bigger image). I would like to see some planets etc if possible.

Do I need any filter to look at the moon through these, I do not want to damage any eyes, especially the kids.

Thankyou in advance..

erick (Eric) · #2 22-05-2007, 09:58 AM

James Kirk (James T. Kirk?).

I have an 8" dob I bought second hand. It's Bintel's premium model - a Guan Sheng scope.

I can answer a couple of questions.

Yes, you'll see a huge amount more than you do with your eye. Yes, the image is bigger (anywhere from 40 times to maybe 260 times bigger), but you do see much more detail because you are able to resolve finer details. Eg, a star that is just one bright point to your eye (eg. Alpha Centauri) is clearly seen to be two close stars when examined at higher magnification.

Venus, Mars, Jupiter and Saturn will all be very interesting sights through the scope.

Viewing the Moon will be bright, but it won't damage eyes. However, most suppliers will include a 1.25" dia neutral density filter (a "Moon filter") as part of the package. If not, ask for one and they'll probably agree. You might need a 2" dia one as well for any 2" eyepiece you have (or maybe to use on the Barlow lens - see below). Sometimes (like at present) you might even want to use the filter when looking at Jupiter (or at Venus in a few months when it is brightest). You'll love the detail you can see on the Moon's surface. Don't just look at full moon - follow the "terminator" (line between sunlight and dark) as it changes position on the surface each evening,

Collimation of the scope will be important - search for "collimation" in the forum (or check the articles section). You will need a collimation tool (cheshire and/or laser).

A Barlow lens would also be useful. I'd suggest a 2" dia, 2 times magnification. That gives you twice the magnification for each eyepiece so you can increase your range of magnification. It will take both 2" eyepieces and 1.25" eyepieces (with its adapter). Also you can put a 2" netural density filter on the bottom of the barlow and then use any eyepiece viewing the Moon without having to worry about fitting filters to the eyepiece.

Try to get a scope with a Crayford-type focusser rather than a rack & pinion-type.

Just a few thoughts to get you started.

I wish I'd started when my children were younger.

Eric

robagar · #3 22-05-2007, 10:26 AM

Quote:

Will I see more than what I can see with the naked eye?

Oh, yes

Definitely agree with Erick's comment about collimation. It's not hard once you get the hang of it, and it makes a big difference.

Oh, and 8" dobs are widely acknowledged to be the best scopes in the world.

erick (Eric) · #4 22-05-2007, 10:34 AM

Quote:

Originally Posted by robagar

.......Oh, and 8" dobs are widely acknowledged to be the best scopes in the world.

Perhaps you and I are biased

Perhaps you'd better add - "when measured in 'bang for buck' ".

rmcpb (Rob) · #5 22-05-2007, 12:08 PM

Welcome to IIS Jimmy

The advice above is the good oil. I would only add that with these scopes it comes down to the "extras" to clinch the deal. Look at the type of focuser, get the Crayford, type of finder scope, range of eyepieces supplied, filters supplied but here I would suggest you only need a moon filter, the others are things you gather on the way.

These scopes are so close that the accessories supplied will make the difference.

BTW 8" dobs rule!!

niko · #6 22-05-2007, 12:24 PM

James,

we've got an 8" dobsonian and two kids (aged 7 and 13).

Here's a few non-tech comments...

We got ours straight out of the box and are using the eyepieces that came with it, never collimated it (but that it the next thing to learn, after 6 months of owning).

Anyway, we see the rings and moons of Saturn, the moons and bands of Jupiter, heaps of nebulas and the moon is amazing - I'm sure we'd see people walking around if there were any up there!

The dob is incredibly easy to use and in a night you can see a lot of different objects - helping to satisfy kids short attention spans.

It's a great choice for a first scope

Go fot it

cheers,

Niko

James Kirk · #7 22-05-2007, 01:24 PM

Many thanks for all of your comments, all noted and not wasted.

I think I will go for the guens heng gs680 mainly for the fact it does not use the rack and pinion focus. Apart from that I seem to think they are very similar.

The only problem with my decision is that no one in Perth sells this and I need to waste money on freight and I have heard that Andrews Comm are rather heavy on freight.

Thanks again

James Kirk

erick (Eric) · #8 22-05-2007, 02:00 PM

James

You might wish to search the threads - this matter (freight costs, including Perth, I think) has been discussed and costs compared over the last few months.

Regards
Eric

ving (David) · #9 22-05-2007, 02:21 PM

beam me up scottie!

yup the 8" is a bit of a sweet spot. the next step up being the 10" which is starting to get heavy and generally one has to carry in 2 parts, however the 8" you can carry in one part... just a bit more convenient i guess. you do sacrifice light gathering tho.
you will be suprised what yu can see in a 8" tho.

while the moon wont actually damage your eyes, having a "moon filter" will relieve the strain and make viewing more comfortable

have fun with your scope

janoskiss (Steve H) · #10 22-05-2007, 02:48 PM

Of the 8" dobs I'd go with the GSO (guan sheng / bintel ...) over the Synta (SW / Saxon...). Bit easier to customise, assemble, disassemble, balance, move around. But there is not much between them so if you get a good price on an 8" Synta, go for it.

ballaratdragons (Ken) · #11 22-05-2007, 03:21 PM

I would recommend the GS 8" over the Skywatcher 8". Not to hurt any dealers, or to put the optics down, but because the GS can be bought with a Crayford Focuser, the Skywatcher can't.

But when you order, specify that you want the Crayford Focuser, otherwise you might end up with the standard Rack & Pinion one, coz GS comes both ways.

James Kirk · #12 22-05-2007, 04:16 PM

Does anyone know who else sells the gs680 apart from Andrews Comm? They are getting me a price for freight tomorrow but I am sure it is going to put me over budget.

Cheers

erick (Eric) · #13 22-05-2007, 04:27 PM

James,

Bintel sells Guan Sheng scopes with their own name on them. Check them out here:-

www.bintelshop.com.au

I'm sure others do as well, I'm not knowledgeable enough. You've checked all your local Perth astro shops? What about Adelaide shops?

Suggestions from anyone else?

Eric

ballaratdragons (Ken) · #14 22-05-2007, 05:19 PM

There are 2 Astro shops that I know of in Perth, surely one of them sells GS Dobs

duncan · #15 22-05-2007, 05:20 PM

Hi James,
I recently bought a 12" Bintel Dob and freight was $300 sent up to Atherton Tablelands. Just west of Cairns in far north Qld. Andrews quoted me $610.
Cheers,
Duncan

ballaratdragons (Ken) · #16 22-05-2007, 05:25 PM

Quote:

Originally Posted by duncan

Hi James,
I recently bought a 12" Bintel Dob and freight was $300 sent up to Atherton Tablelands. Just west of Cairns in far north Qld. Andrews quoted me $610.
Cheers,
Duncan

Thier rates must have gone up! I got charged $40 by Andrews to have mine shipped to country Victoria, and it was a 12".

PeteMo (Pete) · #17 22-05-2007, 05:41 PM

Hi James
Another Perthite here. I had an 8" dob and had great fun with it. Mine was an Optex (made by Synta I think). Either way SW680 or GSO GS680 they will be great.

You do know that BTOW (Binocular Telescope Optical World) at Malaga and NVT at Myaree are both Perth based and deal with SkyWatcher dobs, so postage should be bog all. In fact what you save on the few hundred dollars postage from the Eastern States could get you a 10" dob instead.

Andrews quoted me the following postage rates a few months ago:
$180 10" dob
$200 12" dob

Bintel charge significantly more for their dobs that are BinTel badged GSO's.

James Kirk · #18 22-05-2007, 05:54 PM

Astro shops seem to be a little scarce in Perth.

Have tried both BTOW (Binocular Telescope Optical World) at Malaga and NVT at Myaree but both do not sell the GS680.

If I go for the SW680 I will get it from one of these shops.

PeteMo (Pete) · #19 22-05-2007, 05:54 PM

As for the SkyWatchers, some ARE now coming with Crayford Type focusers instead of Rack & Pinion. I'm holding out for a 10" SkyWatcher dob as the ones arriving at BTOW do have crayfords. You may need to check that Crayfords are on the SW680.

You may want to confirm this, but I heard that the new SkyWatcher 6" and 8" dobs now have a focal length of 1000mm instead of 1200mm. Even so the view will be great.

PeteMo (Pete) · #20 22-05-2007, 05:58 PM

I too had the same dilema before I bought my 8" second hand locally in Perth. In the end I decided that the money saved on postage then would get me a Crayford focuser and a TelRad finder. I never did upgrade so spent the money on an eyepiece instead.

Cheers
Pete