first scope

[James Kirk]

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]

:welcome: 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]

Oh, yes :eyepop:

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]

Perhaps you and I are biased ;)

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

[rmcpb]

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]

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]

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]

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]

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]

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]

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]

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]

James,

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

www.bintelshop.com.au (http://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]

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

[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:thumbsup:

[ballaratdragons]

:eyepop: 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]

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]

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]

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]

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

[luka]

Bintel 8" dob costs $100 more than the nvt one but it comes with much better range of eyepieces and a Crayford focuser. Not sure about postage though...

And please post here what you have ended up buying, I will be getting a dob soon as well (in Perth).

[ballaratdragons]

Sounds like a hint to one of the stores in Perth to sell GS's might be in order :thumbsup:

[TV John]

Hi James

Cant go wrong with an 8" Dob, as someone said plenty of bang for your buck. I'm the new owner of PeteMo's Optex 8" Dob which now has a Crayford focusser and a couple of wide angle 2" eyepieces to go with the 1.25" ones that came with it. Owes me less than $600 and on a dark night I've seen the Cassini division.

Once there's a few more bucks around the HEQ5 will complete the picture allowing photography through it (although have had some success with CCD and dobson turret mount).

Cheers

John

[James Kirk]

Hi

I have another question.

If I purchased the skywatcher sw 680 can I change the rack and pinion focuser to the crayford style?

I ask this as I can get the sw680 in Perth but I do like the gs680 focuser.

Cheers

[janoskiss]

You can change anything you like. :) The most recent SW/Saxon models you should be able to get with Crayford focuser, or an R&P that has a base with bolt-on Synta crayford replacement. If you get an older model, (most likely unless your shop orders a fresh one for you) you will need to do a little more work to fit a crayford focuser. (e.g. drill a few holes)

[James Kirk]

just an update for anyone in Perth looking for an 8" Dob

BTOW SW680 with crayford focuser - $499
NVT SW680 (I think without crayford focuse) $439 +$18 Delivery
Andrews comm GS680 with free binos and crayford focuser - $399 plus $96 delivery.

Let me know if anyone has anything better or other ideas.

cheers

[ballaratdragons]

Sounds like your on a winner with the Andrews price with the Crayford. I thought several hundred delivery to Perth sounded wrong. $96 is fair considering the distance.

[janoskiss]

yes but is it a 10:1 crayford? :)

[James Kirk]

hmmmm more info to learn about.

I was not sure there was a difference in crayfords.

I guess 10:1 is a ratio of sorts.

Are there other crayfords?

Cheers

[mill]

I haven't seen an scope straight out of a normal scope shop with an 10:1 focusser unless you order it with the scope.
The good thing is that 10:1 focussers getting cheaper so maybe very maybe these might become the standard on scopes.

[erick]

James, a 10:1 is a Crayford that has a finer focus knob - I guess ten rotations of it equals one rotation of main focus knob. It won't come standard on these scopes. I haven't played with one yet. My regular Crayford works well, but very sensitive at highest magnification - just needs some practice.

I'm thinking of buying one from Bintel to replace mine - after I get some webcam photography happening!


https://www.bintelshop.com.au/Product.aspx?ID=7207

Down to $119 - very tempting.

[mill]

I have the 10:1 focusser on my 10" dob and it is soooooo smooth and easy, highly recommended for every scope owner.
For photography it is just as good because you can do some really good fine focussing.

[luka]

What about included eyepieces?

[James Kirk]

Hi Luka

From reading the web pages and speaking to BTOW who supply the skywatcher these are the eyepieces supplied with each scope.

SW680 comes with a 10 and 20mm (from speaking to BTOW in Perth)

GS680 comes with 1 x premium possl 9mm and oremium widefield sp26mm. (Reading GS website)

Cheers

[ballaratdragons]

Not to sound like I am plugging Andrews, but he usually supplies 3 EP's with his scopes.

You will find that the EP's that come with Dobs (from any supplier) that they are fairly reasonable. They aren't the bottom of the barrel, but they aren't super-fantastic either. I still use my GS EP's. Over time you may want to step up to better ones, but they are quite OK.

[Shaun]

I just bought an 8" Dob from BTOW it cost me $100 to get it here i am in coolgardie about 550km east of perth, it has a focal length of 1000 with a rack and pinion focus.

I got two eyepieces with this unit a super 10 and super 25 i had some trrouble with the frieght people they damaged the first one before it left perth and stuffed around getting it back to the shop so the owner sent two extra eyepieces as a sweetener a 2x barlows and a 17mm flossel.

The original cost was $399 + $100 del plus i bought a set of filters $75 so for under $600 i have a good set to start with.

This unit has the springs for balance and i think a 9x50 finder have not measured it yet.

I was going to bet the unit from Andrews but was quoted $235 for delivery so it might have been a better idea getting it from andrews $130 more but would have got the Crayford Focus system.

[joe_smith]

http://www.gs-telescope.com/content.asp?id=82

from the Gaun Sheng web site "The deluxe model comes with 2" Micro 10:1 Crayford style focuser and 1.25" adapter."

[Starkler]

The 10:1 fine focuser is definitely worth it. I paid $120 to buy mine and I regard it as money well spent. If you specify that at time of buying it should be cheaper.

[eqcradle]

For the record: I just received one of the 8" SkyWatcher dobs (from MyAstroShop). It's only my first scope, so I'm no expert, but it would appear to be a Crayford focuser on it (no R&P; flat on one side of the tube; smooth action). This was one of the things i had considered before buying - I wasn't actually expecting it to have one.

CL